Polymers

21 pages, 6277 KiB

Open AccessArticle

Characterization and Adsorption Behavior of Newly Synthesized Aminated Cellulose with Jeffamine EDR148 Towards Ni(II), Cu(II), and Pb(II) Heavy Metal Ions

by Jawaher Y. Al Nawah and Amany S. El-Khouly

Polymers 2025, 17(2), 255; https://doi.org/10.3390/polym17020255 - 20 Jan 2025

Viewed by 559

Abstract

Industrial wastewater containing heavy metal ions presents serious economic risk to the environment. In this study, a novel compound of aminated cellulose with jeffamine EDR148 was prepared to improve cellulose’s adsorptive behavior towards metal ions. This study undertook a straightforward and efficient cellulose [...] Read more.

Industrial wastewater containing heavy metal ions presents serious economic risk to the environment. In this study, a novel compound of aminated cellulose with jeffamine EDR148 was prepared to improve cellulose’s adsorptive behavior towards metal ions. This study undertook a straightforward and efficient cellulose modification through homogeneous chlorination in N,N′-butylmethylimidazolium chloride to produce 6-deoxychlorocellulose (Cell-Cl), followed by a reaction with jeffamine EDR148 and ultimately resulting in the formation of aminated cellulose (Cell-Jef148). Structural and chemical characteristics of Cell-Cl and Cell-Jef148 were determined using different techniques. Various adsorption conditions were applied to evaluate the optimal adsorption conditions for the removal of Cu(II), Ni(II), and Pb(II) ions. Cell-Jef48 revealed a greater affinity and higher adsorption efficiency of 480.3, 420.5, and 463.2 mg/g for Cu(II), Ni(II), and Pb(II) ions, respectively. Different kinetics and adsorption isothermal models were studied to investigate the adsorption mechanism and interactions between Cell-Jef148 and metal ions. The results fitted the Langmuir and pseudo-second-order models. Corresponding to the Langmuir model, Cell-Jef148’s maximum adsorption capacities were 952.38, 609.76, and 769.23 mg/g for Cu(II), Ni(II), and Pb(II) ions, respectively, with a high correlation coefficient, R², in the range of 0.99575–0.99855. The research results of this study support Cell-Jef148’s adsorption of heavy metal ions, and the regeneration of adsorbent highlights the potential applications of cellulose-based materials in wastewater treatment. Full article

(This article belongs to the Section Polymer Applications)

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39 pages, 4703 KiB

Open AccessArticle

Mechanisms of the Photomechanical Response in Thin-Film Dye-Doped Glassy Polymers

by Zoya Ghorbanishiadeh, Ankita Bhuyan, Bojun Zhou, Morteza Sheibani Karkhaneh and Mark G. Kuzyk

Polymers 2025, 17(2), 254; https://doi.org/10.3390/polym17020254 - 20 Jan 2025

Viewed by 587

Abstract

This work aims to determine the mechanism of the photomechanical response of poly(Methyl methacrylate) polymer doped with the photo-isomerizable dye Disperse Red 1 using the non-isomerizable dye Disperse Orange 11 as a control to isolate photoisomerization. Samples are free-standing thin films with thickness [...] Read more.

This work aims to determine the mechanism of the photomechanical response of poly(Methyl methacrylate) polymer doped with the photo-isomerizable dye Disperse Red 1 using the non-isomerizable dye Disperse Orange 11 as a control to isolate photoisomerization. Samples are free-standing thin films with thickness that is small compared with the optical skin depth to assure uniform illumination and photomechanical response throughout their volume, which differentiates these studies from most others. Polarization-dependent measurements of the photomechanical stress response are used to deconvolute the contributions of angular hole burning, molecular reorientation and photothermal heating. While photo-isomerization of dopant molecules is commonly observed in dye-doped polymers, the shape changes of a molecule might not couple strongly to the host polymer through steric mechanical interactions, thus not contributing substantially to a macroscopic shape change. To gain insights into the effectiveness of such mechanical coupling, we directly probe the dopant molecules using dichroism measurements simultaneously while measuring the photomechanical response and find mechanical coupling to be small enough to make photothermal heating—mediated by the transfer of optical energy as heat to the polymer—the dominant mechanism. We also predict the fraction of light energy converted to mechanical energy using a model whose parameters are thermodynamic material properties that are measured with independent experiments. We find that in the thin-film geometry, these dye-doped glassy polymers are as efficient as any other material but their large Young’s modulus relative to other organic materials, such as liquid crystal elastomers, makes them suitable in applications that require mechanically strong materials. The mechanical properties and the photomechanical response of thin films are observed to be significantly different than in fibers, suggesting that the geometry of the material and surface effects might play an important role. Full article

(This article belongs to the Special Issue Advanced Stimuli-Responsive Polymer Composites)

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19 pages, 11294 KiB

Open AccessArticle

Experimental Investigation of Durability Properties of Polymer Coated Pumice Aggregate Lightweight Concretes

by Metin Tuncer, Alper Bideci, Bekir Çomak, Gökhan Durmuş and Özlem Sallı Bideci

Polymers 2025, 17(2), 253; https://doi.org/10.3390/polym17020253 - 20 Jan 2025

Viewed by 468

Abstract

Pumice aggregates with low density and high porosity are widely used in lightweight concrete. The high water retention ability of pumice aggregates adversely affects the properties of fresh concrete. Additionally, pumice aggregates’ inadequate mechanical strength and durability hinder concrete performance. In recent years, [...] Read more.

Pumice aggregates with low density and high porosity are widely used in lightweight concrete. The high water retention ability of pumice aggregates adversely affects the properties of fresh concrete. Additionally, pumice aggregates’ inadequate mechanical strength and durability hinder concrete performance. In recent years, research on coated aggregates has gained traction to improve the physical properties, mechanical strength, and durability characteristics of concrete. In this study, coarse pumice aggregates were coated with polyester and partially substituted with uncoated aggregates at ratios of 0%, 25%, 50%, 75%, and 100% in lightweight concrete formulations. Specific weight and water absorption tests were performed on the aggregates, while slump and unit weight tests were performed on fresh concrete mixtures. SEM-EDX analyses, unit weight, water absorbing capacity, sorptivity, compressive strength, freeze-thaw resistance, and sulfate resistance tests were performed on concrete specimens. The results indicated that the polyester coating significantly increased the specific weight of the aggregates and decreased the water absorption rates by up to 85%. Despite the coated aggregates resulting in decreased compressive strength of concrete specimens, they demonstrated reduced water absorbing capacity and sorptivity characteristics relative to reference concrete. Moreover, concrete made with coated aggregates exhibited better results in freeze-thaw and sulphate resistance tests. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites—3rd Edition)

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36 pages, 6105 KiB

Open AccessReview

An Overview of Potential Applications of Environmentally Friendly Hybrid Polymeric Materials

by Raluca Nicoleta Darie-Niță and Stanisław Frąckowiak

Polymers 2025, 17(2), 252; https://doi.org/10.3390/polym17020252 - 20 Jan 2025

Viewed by 939

Abstract

The applications of polymeric materials are being constantly reviewed and improved. In the present world, the word hybrid, and the general idea of combining two or more inherently different approaches, designs, and materials is gaining significant attention. The area of sustainable materials with [...] Read more.

The applications of polymeric materials are being constantly reviewed and improved. In the present world, the word hybrid, and the general idea of combining two or more inherently different approaches, designs, and materials is gaining significant attention. The area of sustainable materials with a low environmental impact is also rapidly evolving with many new discoveries, including the use of materials of a natural origin and countless combinations thereof. This review tries to summarize the current state of knowledge about hybrid polymeric materials and their applications with special attention to the materials that can be considered “environmentally friendly”. As the current application field is quite broad, the review was limited to the following topics: packaging, medical applications, sensors, water purification, and electromagnetic shielding. Furthermore, this review points out the new prospects and challenges for the use of the mentioned materials in terms of creating novel solutions with different nano and micro-materials of mostly natural and renewable origin. Full article

(This article belongs to the Special Issue Advanced Environmentally Friendly Polymeric Materials and Their Applications, 2nd Edition)

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21 pages, 9155 KiB

Open AccessArticle

Antimicrobial Activity of UV-Activated and Cysteamine-Grafted Polymer Foils Against Bacteria and Algae

by Viktorie Neubertová, Tereza Silovská, Václav Švorčík and Zdeňka Kolská

Polymers 2025, 17(2), 251; https://doi.org/10.3390/polym17020251 - 20 Jan 2025

Viewed by 590

Abstract

Surface modification of various polymer foils was achieved by UV activation and chemical grafting with cysteamine to improve surface properties and antimicrobial efficacy. UVC activation at 254 nm led to changes in surface wettability and charge density, which allowed the introduction of amino [...] Read more.

Surface modification of various polymer foils was achieved by UV activation and chemical grafting with cysteamine to improve surface properties and antimicrobial efficacy. UVC activation at 254 nm led to changes in surface wettability and charge density, which allowed the introduction of amino and thiol functional groups by cysteamine grafting. X-ray photoelectron spectroscopy (XPS) confirmed increased nitrogen and sulfur content on the modified surfaces. SEM analysis revealed that UV activation and cysteamine grafting resulted in distinct surface roughness and texturing, which are expected to enhance microbial interactions. Antimicrobial tests showed increased resistance to algal growth (inhibition test) and bacterial colonization (drop plate method), with significant improvement observed for polyethylene terephthalate (PET) and polyetheretherketone (PEEK) foils. The important factors influencing the efficacy included UV exposure time and cysteamine concentration, with longer exposure and higher concentrations leading to bacterial reduction of up to 45.7% for Escherichia coli and 55.6% for Staphylococcus epidermidis. These findings highlight the potential of combining UV activation and cysteamine grafting as an effective method for developing polymeric materials with enhanced antimicrobial function, offering applications in industries such as healthcare and packaging. Full article

(This article belongs to the Section Polymer Applications)

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10 pages, 4269 KiB

Open AccessCommunication

Characterization of Self-Cured Silicone Oils for Encapsulation of Ultraviolet-C Light-Emitting Diodes

by Xing Qiu, Qianhang Yu, Yuanjie Cheng, Jeffery C. C. Lo and Shi-wei Ricky Lee

Polymers 2025, 17(2), 250; https://doi.org/10.3390/polym17020250 - 20 Jan 2025

Viewed by 447

Abstract

The effectiveness of ultraviolet-C light-emitting diodes (UVC LEDs) is currently limited by the lack of suitable encapsulation materials, restricting their use in sterilization, communication, and in vivo cancer tumor inhibition. This study evaluates various silicone oils for UVC LED encapsulation. A material aging [...] Read more.

The effectiveness of ultraviolet-C light-emitting diodes (UVC LEDs) is currently limited by the lack of suitable encapsulation materials, restricting their use in sterilization, communication, and in vivo cancer tumor inhibition. This study evaluates various silicone oils for UVC LED encapsulation. A material aging experiment was conducted on CF1040 (octamethylcyclotetrasiloxane), HF2020 (methyl hydro polysiloxanes), and MF2020-1000 (polydimethylsiloxane) under UVC radiation for 1000 h. The analysis assessed transmittance changes and chemical composition alterations throughout the aging process. Notably, HF2020 showed an increase in transmittance before 500 h, indicating a curing process attributed to the photolysis of Si-H, leading to the formation of Si-O-Si. Further testing on 265 nm UVC LEDs, both with and without HF2020 encapsulation, showed that the encapsulated LEDs exhibited a remarkable maximum increase of 27% in radiant power compared to their unencapsulated counterparts. Additionally, these encapsulated LEDs sustained higher radiant power levels during the first 200 h of operation. Notably, its potential application in photodynamic therapy is significant; by activating photosensitizers with higher UVC exposure, it facilitates the rapid production of reactive oxygen species, leading to effective cancer cell destruction within a short timeframe. Full article

(This article belongs to the Section Polymer Analysis and Characterization)

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22 pages, 5302 KiB

Open AccessReview

Recent Advancements of Bio-Derived Flame Retardants for Polymeric Materials

by Min Chen, Qinhe Guo, Yao Yuan, Ao Li, Bo Lin, Yi Xiao, Lulu Xu and Wei Wang

Polymers 2025, 17(2), 249; https://doi.org/10.3390/polym17020249 - 20 Jan 2025

Viewed by 612

Abstract

The sustainable flame retardancy of polymeric materials is a key focus for the direction of the next generation in the field of fire safety. Bio-derived flame retardants are gaining attention as environmentally friendly additives due to their low ecological impact and decreasing costs. [...] Read more.

The sustainable flame retardancy of polymeric materials is a key focus for the direction of the next generation in the field of fire safety. Bio-derived flame retardants are gaining attention as environmentally friendly additives due to their low ecological impact and decreasing costs. These compounds can enhance char formation in polymeric materials by swelling upon heating, attributed to their functional groups. This review explores various biomolecules used as flame retardants, including phytic acid, chitosan, lignin, tannic acid, and bio-derived phosphorus and nitrogen compounds, emphasizing their flame-retardant properties and compatibility with different polymer matrices. The primary focus is on the structural characteristics, modifications, and flame-retardant behaviors of these bio-derived additives, particularly regarding their mechanisms of action within polymeric materials. Finally, the review explores the opportunities, current challenges, and future directions for the practical application of bio-derived flame retardants in polymer materials. Full article

(This article belongs to the Special Issue Recent Advances in Flame-Retardant Polymeric Materials)

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14 pages, 3084 KiB

Open AccessArticle

Effects of Additional Flexible and Rigid Structure on BDT-BDD Terpolymer and the Performance of Organic Solar Cells

by Xin Jing, Xuebing Li, Yong Zhao, Quanliang Wang, Xiao Kang, Xiaojie Liu, Aziz Saparbaev, Feng Li and Mingliang Sun

Polymers 2025, 17(2), 248; https://doi.org/10.3390/polym17020248 - 20 Jan 2025

Viewed by 442

Abstract

In organic solar cells, the aggregation and crystallization of polymers are significant for bulk heterojunction. Blending with acceptor materials, polymer donor materials can adjust their aggregation by the movement of the chain segments. In this paper, the unfused structures based on thiophene and [...] Read more.

In organic solar cells, the aggregation and crystallization of polymers are significant for bulk heterojunction. Blending with acceptor materials, polymer donor materials can adjust their aggregation by the movement of the chain segments. In this paper, the unfused structures based on thiophene and carbazole are respectively designed and introduced into the donor-acceptor copolymer donor materials to investigate the influence of flexible and rigid structures on polymer-aggregation leading photoelectric performance. The material and quantum chemical property investigations show that the selection and design of the blocks are important for the properties of the terpolymers, and the resulting polymer:Y6 devices achieve improvements in performance from 13.85% to 15.66% (especially for fill factors from 63.37% up to 69.81%). This result contributes to designing and optimizing efficient polymers. Full article

(This article belongs to the Section Polymer Applications)

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33 pages, 5113 KiB

Open AccessReview

Nanoparticle-Doped Antibacterial and Antifungal Coatings

by Devyani Thapliyal, George D. Verros and Raj Kumar Arya

Polymers 2025, 17(2), 247; https://doi.org/10.3390/polym17020247 - 20 Jan 2025

Viewed by 1056

Abstract

Antimicrobial polymeric coatings rely not only on their surface functionalities but also on nanoparticles (NPs). Antimicrobial coatings gain their properties from the addition of NPs into a polymeric matrix. NPs that have been used include metal-based NPs, metal oxide NPs, carbon-based nanomaterials, and [...] Read more.

Antimicrobial polymeric coatings rely not only on their surface functionalities but also on nanoparticles (NPs). Antimicrobial coatings gain their properties from the addition of NPs into a polymeric matrix. NPs that have been used include metal-based NPs, metal oxide NPs, carbon-based nanomaterials, and organic NPs. Copper NPs and silver NPs exhibit antibacterial and antifungal properties. So, when present in coatings, they will release metal ions with the combined effect of having bacteriostatic/bactericidal properties, preventing the growth of pathogens on surfaces covered by these nano-enhanced films. In addition, metal oxide NPs such as titanium dioxide NPs (TiO₂ NPs) and zinc oxide NPs (ZnONPs) are used as NPs in antimicrobial polymeric coatings. Under UV irradiation, these NPs show photocatalytic properties that lead to the production of reactive oxygen species (ROS) when exposed to UV radiation. After various forms of nano-carbon materials were successfully developed over the past decade, they and their derivatives from graphite/nanotubes, and composite sheets have been receiving more attention because they share an extremely large surface area, excellent mechanical strength, etc. These NPs not only show the ability to cause oxidative stress but also have the ability to release antimicrobial chemicals under control, resulting in long-lasting antibacterial action. The effectiveness and life spans of the antifouling performance of a variety of polymeric materials have been improved by adding nano-sized particles to those coatings. Full article

(This article belongs to the Special Issue Development of Polymer Materials as Functional Coatings)

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28 pages, 6105 KiB

Open AccessArticle

Exploring the Effect of Annealing on PLA/Carbon Nanotube Nanocomposites: In Search of Efficient PLA/MWCNT Nanocomposites for Electromagnetic Shielding

by Flávio Urbano da Silva, Carlos Bruno Barreto Luna, Fabiano Santana da Silva, José Vinícius Melo Barreto, Debora Pereira Schmitz, Bluma Guenther Soares, Renate Maria Ramos Wellen and Edcleide Maria Araújo

Polymers 2025, 17(2), 246; https://doi.org/10.3390/polym17020246 - 20 Jan 2025

Viewed by 622

Abstract

In this research, poly(lactic acid) (PLA) nanocomposites with multi-walled carbon nanotubes (MWCNT) were produced by extrusion, injection, and compression molding, focusing on electromagnetic shielding. Various amounts of carbon nanotubes (MWCNTs) were tested in PLA matrix, specifically ranging from 1 to 4 parts per [...] Read more.

In this research, poly(lactic acid) (PLA) nanocomposites with multi-walled carbon nanotubes (MWCNT) were produced by extrusion, injection, and compression molding, focusing on electromagnetic shielding. Various amounts of carbon nanotubes (MWCNTs) were tested in PLA matrix, specifically ranging from 1 to 4 parts per hundred resin (phr). The resulting nanocomposites were analyzed before and after undergoing annealing heat treatment. It was observed that as the MWCNT content increased, the melt flow index of PLA decreased. This reduction indicates that the nanotubes were effectively accommodated into the PLA chain. The PLA/MWCNT (2 phr) formulation presented the greatest balance of properties, with potential for electromagnetic shielding application. Scanning electron microscopy (SEM) demonstrated that incorporating 2 phr of carbon nanotubes in PLA promoted good distribution, favoring high electrical conductivity and electromagnetic shielding between 20–22 dB (8.2–18 GHz), corresponding to approximately 99% attenuation. Furthermore, its properties, such as elastic modulus (3156 MPa), tensile strength (65.1 MPa), hardness (77.8 Shore D), and heat deflection temperature (55.3 °C), increased compared to pure PLA. After annealing, the PLA/MWCNT (2 phr) nanocomposite underwent a molecular reordering, resulting in an increased crystalline fraction, as confirmed by X-ray diffraction (XRD). However, the electrical conductivity maintained the same order of magnitude, while the electromagnetic shielding varied from 19.7 to 20 dB. The results indicate that these nanocomposites are promising for electromagnetic shielding applications and can be manufactured in the molten state. Full article

(This article belongs to the Special Issue Mechanic Properties of Polymer Materials)

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15 pages, 5423 KiB

Open AccessArticle

Prediction Model for Flake Line Defects in Metallic Injection Molding: Considering Skin-Core Velocity and Alignment

by Seungkwon Choi, Donghwi Park, Seungcheol Lee, Minho Song and Naksoo Kim

Polymers 2025, 17(2), 245; https://doi.org/10.3390/polym17020245 - 20 Jan 2025

Viewed by 426

Abstract

Metallic injection molding combines aluminum flake metallic pigments with polymers to directly produce components with metallic luster, improving production efficiency and reducing environmental impact. However, flake line defects that occur in regions where ribs or flow paths intersect remain a significant challenge. This [...] Read more.

Metallic injection molding combines aluminum flake metallic pigments with polymers to directly produce components with metallic luster, improving production efficiency and reducing environmental impact. However, flake line defects that occur in regions where ribs or flow paths intersect remain a significant challenge. This study proposes a velocity model that considers the flow characteristics between the surface and core layers and an alignment model that incorporates the orientation of aluminum flakes to predict appearance defects. Through this approach, the mechanisms of appearance defect formation were systematized, and the appearance defects caused by flow velocity differences between the surface and core layers, flake alignment uniformity, and reflection angles were visualized. Both prediction models demonstrated a 50% prediction accuracy, successfully identifying two out of four observed defects. This research addresses the limitations of previous prediction methods, which only considered the surface layer, by introducing a novel approach that accounts for the core layer. It is expected to contribute to reducing defects and improving quality in industries requiring high-quality metallic appearances. Full article

(This article belongs to the Special Issue Additive Manufacturing of Polymer Based Materials)

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20 pages, 4819 KiB

Open AccessArticle

Experimental Study on the Application of Polymer Agents in Offshore Oil Fields: Optimization Design for Enhanced Oil Recovery

by Xianjie Li, Jian Zhang, Yaqian Zhang, Cuo Guan, Zheyu Liu, Ke Hu, Ruokun Xian and Yiqiang Li

Polymers 2025, 17(2), 244; https://doi.org/10.3390/polym17020244 - 20 Jan 2025

Viewed by 525

Abstract

The Bohai oilfield is characterized by severe heterogeneity and high average permeability, leading to a low water flooding recovery efficiency. Polymer flooding only works for a certain heterogeneous reservoir. Therefore, supplementary technologies for further enlarging the swept volume are still necessary. Based on [...] Read more.

The Bohai oilfield is characterized by severe heterogeneity and high average permeability, leading to a low water flooding recovery efficiency. Polymer flooding only works for a certain heterogeneous reservoir. Therefore, supplementary technologies for further enlarging the swept volume are still necessary. Based on the concept of discontinuous chemical flooding with multi slugs, three chemical systems, which were polymer gel (PG), hydrophobically associating polymer (polymer A), and conventional polymer (polymer B), were selected as the profile control and displacing agents. The optimization design of the discontinuous chemical flooding was investigated by core flooding experiments and displacement equilibrium degree calculation. The gel, polymer A, and polymer B were classified into three levels based on their profile control performance. The degree of displacement equilibrium was defined by considering the sweep conditions and oil displacement efficiency of each layer. The effectiveness of displacement equilibrium degree was validated through a three-core parallel displacement experiment. Additionally, the parallel core displacement experiment optimized the slug size, combination method, and shift timing of chemicals. Finally, a five-core parallel displacement experiment verified the enhanced oil recovery (EOR) performance of discontinuous chemical flooding. The results show that the displacement equilibrium curve exhibited a stepwise change. The efficiency of discontinuous chemical flooding became more significant with the number of layers increasing and heterogeneity intensifying. Under the combination of permeability of 5000/2000/500 mD, the optimal chemical dosage for the chemical discontinuous flooding was a 0.7 pore volume (PV). The optimal combination pattern was the alternation injection in the form of “medium-strong-weak-strong-weak”, achieving a displacement equilibrium degree of 82.3%. The optimal shift timing of chemicals occurred at a water cut of 70%, yielding a displacement equilibrium degree of 87.7%. The five-core parallel displacement experiment demonstrated that discontinuous chemical flooding could get a higher incremental oil recovery of 24.5% compared to continuous chemical flooding, which presented a significantly enhanced oil recovery potential. Full article

(This article belongs to the Special Issue New Studies of Polymer Surfaces and Interfaces)

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14 pages, 7480 KiB

Open AccessArticle

Electrospinning Membrane with Polyacrylate Mixed Beta-Cyclodextrin: An Efficient Adsorbent for Cationic Dyes

by Chunling Zheng, Wei Zhao, Xiaoqian Tu and Shaoqiang Zhou

Polymers 2025, 17(2), 243; https://doi.org/10.3390/polym17020243 - 20 Jan 2025

Viewed by 488

Abstract

A simple and non-chemical binding nanofiber (β-CD/PA) adsorbent was obtained by electrospinning a mixture of β-cyclodextrin (β-CD) and polyacrylate (PA). The cationic dyes in wastewater were removed by the host–guest inclusion complex of the β-cyclodextrin and the [...] Read more.

A simple and non-chemical binding nanofiber (β-CD/PA) adsorbent was obtained by electrospinning a mixture of β-cyclodextrin (β-CD) and polyacrylate (PA). The cationic dyes in wastewater were removed by the host–guest inclusion complex of the β-cyclodextrin and the electrostatic interaction between the polyacrylate and the dyes groups. The influence of the content of β-cyclodextrin on the surface morphology and adsorption capacity of the nanofiber membrane was discussed, and the optimized adsorption capacity of nanofiber adsorption material was determined. The adsorption capacity of nanofiber adsorbents for basic red 9, basic red 14, basic red 46, basic blue 9, basic yellow 19 and basic yellow 28 was 86.71 mg/g, 21.513 mg/g, 18.926 mg/g, 44.525 mg/g, 116.516 mg/g and 155.206 mg/g, respectively. The effects of different initial concentrations and pH values on the adsorption properties of adsorbent materials were studied. The kinetic analysis showed that the adsorption process of nanofibers for cationic dyes was more in line with the pseudo-second-order kinetic adsorption model. Moreover, nanofiber adsorbent could be easily separated from the dye solution and showed high recycling efficiency. These results indicated that the β-cyclodextrin/polyacrylate composite nanofibers are expected to be recyclable adsorbents in dye wastewater treatment. Full article

(This article belongs to the Special Issue Multifunctional Application of Electrospun Fiber)

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18 pages, 7310 KiB

Open AccessArticle

Effects of Hydroxyapatite Additions on Alginate Gelation Kinetics During Cross-Linking

by Katarina Dimic-Misic, Monir Imani and Michael Gasik

Polymers 2025, 17(2), 242; https://doi.org/10.3390/polym17020242 - 19 Jan 2025

Viewed by 768

Abstract

Alginate hydrogels have gathered significant attention in biomedical engineering due to their remarkable biocompatibility, biodegradability, and ability to encapsulate cells and bioactive molecules, but much less has been reported on the kinetics of gelation. Scarce experimental data are available on cross-linked alginates (AL) [...] Read more.

Alginate hydrogels have gathered significant attention in biomedical engineering due to their remarkable biocompatibility, biodegradability, and ability to encapsulate cells and bioactive molecules, but much less has been reported on the kinetics of gelation. Scarce experimental data are available on cross-linked alginates (AL) with bioactive components. The present study addressed a novel method for defining the crosslinking mechanism using rheological measurements for aqueous mixtures of AL and calcium chloride (CaCl₂) with the presence of hydroxyapatite (HAp) as filler particles. The time-dependent crosslinking behaviour of these mixtures was exploited using a plate–plate rheometer, when crosslinking occurs due to calcium ions (Ca²⁺) binding to the guluronic acid blocks within the AL polymer, forming a stable “egg-box” structure. To reveal the influence of HAp particles as filler on crosslinked sample morphology, after rheological measurement and crosslinking, crosslinked samples were freeze-dried and their morphology was assessed using an optical microscope and SEM. It was found that the addition of HAp particles, which are known to enhance the mechanical properties and biocompatibility of crosslinked AL gels, significantly decreased (usually rapidly) the interaction between the Ca²⁺ and AL chains. In this research, the physical “shielding” effect of HAp particles on the crosslinking of AL with Ca²⁺ ions has been observed for the first time, and its crosslinking behaviour was defined using rheological methods. After crosslinking and rheometer measurements, the samples were further evaluated for morphological properties and the observations were correlated with their dewatering properties. While the presence of HAp particles led to a slower crosslinking process and a more uniform development of the rheological parameters, it also led to a more uniform porosity and improved dewatering properties. The observed effects allow for a better understanding of the crosslinking process kinetics, which directly affects the physical and chemical properties of the AL gels. The shielding behaviour (retardation) of filler particles occurs when they physically or chemically block certain components in a mixture, delaying their interaction with other reactants. In hydrogel formulations, filler particles like hydroxyapatite (HAp) can act as barriers, adsorbing onto reactive components or creating physical separation, which slows the reaction rate and allows for controlled gelation or delayed crosslinking. This delayed reactivity is beneficial for precise control over the reaction timing, enabling the better manipulation of material properties such as crosslinking distribution, pore structure, and mechanical stability. In this research, the physical shielding effect of HAp particles was observed through changes in rheological properties during crosslinking and was dependent on the HAp concentration. The addition of HAp also enabled more uniform porosity and improved dewatering properties. The observed effects allow for a better understanding of the crosslinking process kinetics, which directly affects the physical and chemical properties of the AL gels. Full article

(This article belongs to the Special Issue Polymer Hydrogels: Synthesis, Properties and Applications)

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18 pages, 7230 KiB

Open AccessArticle

An Extensive Study of an Eco-Friendly Fireproofing Process of Lignocellulosic Miscanthus × giganteus Particles and Their Application in Flame-Retardant Panels

by Yasmina Khalaf, Rodolphe Sonnier, Nicolas Brosse and Roland El Hage

Polymers 2025, 17(2), 241; https://doi.org/10.3390/polym17020241 - 19 Jan 2025

Viewed by 701

Abstract

Increasing the flame retardancy of lignocellulosic materials such as Miscanthus × giganteus can effectively enable their wide use. This study examines the fireproofing process of Miscanthus particles using an eco-friendly process by grafting phytic acid and urea in aqueous solution. Miscanthus particles underwent [...] Read more.

Increasing the flame retardancy of lignocellulosic materials such as Miscanthus × giganteus can effectively enable their wide use. This study examines the fireproofing process of Miscanthus particles using an eco-friendly process by grafting phytic acid and urea in aqueous solution. Miscanthus particles underwent a steam explosion step before being grafted. Fireproof binderless particle panels were manufactured from miscanthus particles with or without adding olive pomace by hot-pressing. The effect of the steam explosion and/or the flame-retardant treatment on the morphology, chemical composition and thermal stability of the particles, as well as the thermal stability of the panels, was investigated. The results showed that water impregnation followed by a steam explosion at 210 °C for 8 min resulted in particles that were rich in lignin and more homogeneous in size (length and width). Fireproof particles were produced with relatively low P and N contents. The flame retardancy of the binderless particle panels was significantly improved when using miscanthus particles treated with phytic acid and urea, as shown by a reduced heat release (HRR) and an increased time-to-ignition. However, the presence of olive pomace significantly decreased the flame retardancy of the panels. Binderless particle panels prepared from grafted miscanthus particles showed the best fire properties and are considered fireproof. Full article

(This article belongs to the Section Polymer Applications)

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19 pages, 8711 KiB

Open AccessArticle

Production and Characterization of H. perforatum Oil-Loaded, Semi-Resorbable, Tri-Layered Hernia Mesh

by Özlem Eğri, Feyza Güneş and Sinan Eğri

Polymers 2025, 17(2), 240; https://doi.org/10.3390/polym17020240 - 19 Jan 2025

Viewed by 520

Abstract

Hernia repair is the most common surgical operation applied worldwide. Mesh prostheses are used to support weakened or damaged tissue to decrease the risk of hernia recurrence. However, the patches currently used in clinic applications have significant short-term and long-term risks. This study [...] Read more.

Hernia repair is the most common surgical operation applied worldwide. Mesh prostheses are used to support weakened or damaged tissue to decrease the risk of hernia recurrence. However, the patches currently used in clinic applications have significant short-term and long-term risks. This study aimed to design, produce, and characterize a three-layered semi-resorbable composite hernia mesh using the electrospinning technique, where the upper layer (parietal side) was made of non-resorbable polypropylene (PP-Cl) fibers, the partially resorbable middle layer was made of PP-Cl and polycaprolactone (PCL) fibers, and the fully resorbable lower layer (visceral side) was made of H. perforatum oil-loaded polyethylene glycol (PEG) fibers. The extracellular matrix-like fibrous structure of the patches provided low density and high porosity, minimizing the risk of long-term foreign body reactions, and the hydrophilic/hydrophobic character of the surfaces and the detected swelling rates supported biocompatibility. The patches exhibited mechanical properties comparable to commercially available products. Controlled release of therapeutic oil could be achieved from the oil-integrated patches due to the dissolution of PEG in the acute process. In vitro cell culture studies with the L929 mouse fibroblast cell line revealed that the meshes do not have a cytotoxic nor a biomaterial-induced necrotic effect that will induce apoptosis of the cells. The visceral side of the meshes exhibited non-adherence of cell-like structures to the surface due to the dissolution of PEG. The composite hernia patches were concluded to reduce the risk of adhering to internal organs in the hernia area, have the potential to be used in in vivo biomedical applications, and will support the search for an ideal hernia mesh that can be used in the treatment of abdominal hernias. Full article

(This article belongs to the Topic Advanced Biomaterials: Processing and Applications)

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81 pages, 17721 KiB

Open AccessReview

Interactive Coupling Relaxation of Dipoles and Wagner Charges in the Amorphous State of Polymers Induced by Thermal and Electrical Stimulations: A Dual-Phase Open Dissipative System Perspective

by Jean Pierre Ibar

Polymers 2025, 17(2), 239; https://doi.org/10.3390/polym17020239 - 19 Jan 2025

Viewed by 490

Abstract

This paper addresses the author’s current understanding of the physics of interactions in polymers under a voltage field excitation. The effect of a voltage field coupled with temperature to induce space charges and dipolar activity in dielectric materials can be measured by very [...] Read more.

This paper addresses the author’s current understanding of the physics of interactions in polymers under a voltage field excitation. The effect of a voltage field coupled with temperature to induce space charges and dipolar activity in dielectric materials can be measured by very sensitive electrometers. The resulting characterization methods, thermally stimulated depolarization (TSD) and thermal-windowing deconvolution (TWD), provide a powerful way to study local and cooperative relaxations in the amorphous state of matter that are, arguably, essential to understanding the glass transition, molecular motions in the rubbery and molten states and even the processes leading to crystallization. Specifically, this paper describes and tries to explain ‘interactive coupling’ between molecular motions in polymers by their dielectric relaxation characteristics when polymeric samples have been submitted to thermally induced polarization by a voltage field followed by depolarization at a constant heating rate. Interactive coupling results from the modulation of the local interactions by the collective aspect of those interactions, a recursive process pursuant to the dynamics of the interplay between the free volume and the conformation of dual-conformers, two fundamental basic units of the macromolecules introduced by this author in the “dual-phase” model of interactions. This model reconsiders the fundamentals of the TSD and TWD results in a different way: the origin of the dipoles formation, induced or permanent dipoles; the origin of the Wagner space charges and the T_g,ρ transition; the origin of the T_LL manifestation; the origin of the Debye elementary relaxations’ compensation or parallelism in a relaxation map; and finally, the dual-phase origin of their super-compensations. In other words, this paper is an attempt to link the fundamentals of TSD and TWD activation and deactivation of dipoles that produce a current signal with the statistical parameters of the “dual-phase” model of interactions underlying the Grain-Field Statistics. Full article

(This article belongs to the Special Issue Editorial Board Members' Collection Series: Polymer Physics and Theory—2nd Edition)

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19 pages, 3206 KiB

Open AccessArticle

Impact of Thermal Treatment and Aging on Lignin Properties in Spruce Wood: Pathways to Value-Added Applications

by František Kačík, Eva Výbohová, Tereza Jurczyková, Adriana Eštoková, Elena Kmeťová and Danica Kačíková

Polymers 2025, 17(2), 238; https://doi.org/10.3390/polym17020238 - 18 Jan 2025

Viewed by 498

Abstract

Thermal modification is an environmentally friendly process that does not utilize chemical agents to enhance the stability and durability of wood. The use of thermally modified wood results in a significantly extended lifespan compared with untreated wood, with minimal maintenance requirements, thereby reducing [...] Read more.

Thermal modification is an environmentally friendly process that does not utilize chemical agents to enhance the stability and durability of wood. The use of thermally modified wood results in a significantly extended lifespan compared with untreated wood, with minimal maintenance requirements, thereby reducing the carbon footprint. This study examines the impact of varying modification temperatures (160, 180, and 210 °C) on the lignin of spruce wood using the ThermoWood process and following the accelerated aging of thermally modified wood. Wet chemistry methods, including nitrobenzene oxidation (NBO), size exclusion chromatography (SEC), thermogravimetry (TG), differential thermogravimetry (DTG), and Fourier transform infrared spectroscopy (FTIR), were employed to investigate the alterations in lignin. At lower modification temperatures, the predominant reaction is the degradation of lignin, which results in a reduction in the molecular weight and an enhanced yield of NBO (vanillin and vanillic acid) products. At elevated temperatures, condensation and repolymerization reactions become the dominant processes, increasing these traits. The lignin content of aged wood is higher than that of thermally modified wood, which has a lower molecular weight and a lower decomposition temperature. The results demonstrate that lignin isolated from thermally modified wood at the end of its life cycle is a promising feedstock for carbon-based materials and the production of a variety of aromatic monomers, including phenols, aromatic aldehydes and acids, and benzene derivatives. Full article

(This article belongs to the Special Issue Advances in Applied Lignin Research)

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22 pages, 3957 KiB

Open AccessReview

Damping Optimization and Energy Absorption of Mechanical Metamaterials for Enhanced Vibration Control Applications: A Critical Review

by Fayyaz, Salem Bashmal, Aamer Nazir, Sikandar Khan and Abdulrahman Alofi

Polymers 2025, 17(2), 237; https://doi.org/10.3390/polym17020237 - 18 Jan 2025

Viewed by 598

Abstract

Metamaterials are pushing the limits of traditional materials and are fascinating frontiers in scientific innovation. Mechanical metamaterials (MMs) are a category of metamaterials that display properties and performances that cannot be realized in conventional materials. Exploring the mechanical properties and various aspects of [...] Read more.

Metamaterials are pushing the limits of traditional materials and are fascinating frontiers in scientific innovation. Mechanical metamaterials (MMs) are a category of metamaterials that display properties and performances that cannot be realized in conventional materials. Exploring the mechanical properties and various aspects of vibration and damping control is becoming a crucial research area. Their geometries have intricate features inspired by nature, which make them challenging to model and fabricate. The fabrication of MMs has become possible because of the emergence of additive manufacturing (AM) technology. Mechanical vibrations in engineering applications are common and depend on inertia, stiffness, damping, and external excitation. Vibration and damping control are important aspects of MM in vibrational environments and need to be enhanced and explored. This comprehensive review covers different vibration and damping control aspects of MMs fabricated using polymers and other engineering materials. Different morphological configurations of MMs are critically reviewed, covering crucial vibration aspects, including bandgap formation, energy absorption, and damping control to suppress, attenuate, isolate, and absorb vibrations. Bandgap formation using different MM configurations is presented and reviewed. Furthermore, studies on the energy dissipation and absorption of MMs are briefly discussed. In addition, the vibration damping of various lattice structures is reviewed along with their analytical modeling and experimental measurements. Finally, possible research gaps are highlighted, and a general systematic procedure to address these areas is suggested for future research. This review paper may lay a foundation for young researchers intending to start and pursue research on additive-manufactured MM lattice structures for vibration control applications. Full article

(This article belongs to the Section Polymer Processing and Engineering)

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21 pages, 3774 KiB

Open AccessReview

Cellulose-Based Aerogels for Environmentally Sustainable Applications: A Review of the Production, Modification, and Sorption of Environmental Contaminants

by Fernanda Wickboldt Stark, Pascal Silas Thue, André Luiz Missio, Fernando Machado Machado, Rafael de Avila Delucis and Robson Andreazza

Polymers 2025, 17(2), 236; https://doi.org/10.3390/polym17020236 - 18 Jan 2025

Viewed by 607

Abstract

Environmental pollution, stemming from the disposal of contaminants, poses severe threats to ecosystems and human health. The emergence of a new class of pollutants, termed emerging contaminants (ECs), in soil, water, and air has raised global concerns, aligning with the UN 2030 Agenda’s [...] Read more.

Environmental pollution, stemming from the disposal of contaminants, poses severe threats to ecosystems and human health. The emergence of a new class of pollutants, termed emerging contaminants (ECs), in soil, water, and air has raised global concerns, aligning with the UN 2030 Agenda’s Sustainable Development Goals. Aerogels, three-dimensional structures with high porosity and low density, offer promise in addressing this issue. Cellulose-based aerogels, derived from abundant, renewable, and biodegradable sources, particularly stand out for their potential in adsorption applications. However, challenges arise in water and wastewater treatment due to cellulose aerogel’s inherent hydrophilicity. To overcome this limitation, incorporating new components and employing modification processes becomes essential. This article explores the production phases and diverse modifications of cellulose aerogels, aiming to enhance their adsorption capabilities for various environmental contaminants. By addressing hydrophilicity issues and developing stable composites, cellulose aerogels can contribute significantly to efficient and sustainable solutions in the quest for cleaner ecosystems and improved human health. Full article

(This article belongs to the Special Issue Feature Papers in Biomacromolecules, Biobased and Biodegradable Polymers, 3rd Edition)

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27 pages, 10551 KiB

Open AccessArticle

Zero Waste Concept in Production of PLA Biocomposites Reinforced with Fibers Derived from Wild Plant (Spartium junceum L.) and Energy Crop (Sida hermaphrodita (L.) Rusby)

by Zorana Kovačević, Ana Pilipović, Mario Meheš and Sandra Bischof

Polymers 2025, 17(2), 235; https://doi.org/10.3390/polym17020235 - 18 Jan 2025

Viewed by 512

Abstract

This research follows the principles of circular economy through the zero waste concept and cascade approach performed in two steps. Our paper focuses on the first step and explores the characteristics of developed biocomposite materials made from a biodegradable poly(lactic acid) polymer (PLA) [...] Read more.

This research follows the principles of circular economy through the zero waste concept and cascade approach performed in two steps. Our paper focuses on the first step and explores the characteristics of developed biocomposite materials made from a biodegradable poly(lactic acid) polymer (PLA) reinforced with natural fibers isolated from the second generation of biomass (agricultural biomass and weeds). Two plants, Spartium junceum L. (SJL) and Sida hermaphrodita (SH), were applied. To enhance their mechanical, thermal, and antimicrobial properties, their modification was performed with environmentally friendly additives—linseed oil (LO), organo-modified montmorillonite nanoclay (MMT), milled cork (MC), and zinc oxide (ZnO). The results revealed that SH fibers exhibited 38.92% higher tensile strength than SJL fibers. Composites reinforced with SH fibers modified only with LO displayed a 27.33% increase in tensile strength compared to neat PLA. The addition of LO improved the thermal stability of both biocomposites by approximately 5–7 °C. Furthermore, the inclusion of MMT filler significantly reduced the flammability, lowering the heat release rate to 30.25%, and enabling the categorization of developed biocomposite in a group of flame retardants. In the second step, all waste streams generated during the fibers extraction process are repurposed into the production of solid biofuels (pellets, briquettes) or biogas (bio)methane. Full article

(This article belongs to the Special Issue Biodegradable Polymers: Innovations in Processing, Diverse Applications, and Sustainable Solutions)

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12 pages, 1151 KiB

Open AccessArticle

Microbial Adhesion and Cytotoxicity of Heat-Polymerized and 3D-Printed Denture Base Materials when Modified with Dimethylaminohexadecyl Methacrylate and/or 2-Methacryloyloxyethyl Phosphorylcholine as Antimicrobial and Protein-Repellent Materials

by Njood F. AlAzzam, Salwa O. Bajunaid, Bashayer H. Baras, Heba A. Mitwalli, Michael D. Weir and Hockin H. K. Xu

Polymers 2025, 17(2), 228; https://doi.org/10.3390/polym17020228 - 18 Jan 2025

Viewed by 459

Abstract

Background: Polymethyl methacrylate (PMMA) is ideal for denture bases but is prone to biofilm accumulation, leading to denture stomatitis (DS), often involving Candida albicans. Dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC) are introduced into dental materials for their antimicrobial and protein-repellent properties. [...] Read more.

Background: Polymethyl methacrylate (PMMA) is ideal for denture bases but is prone to biofilm accumulation, leading to denture stomatitis (DS), often involving Candida albicans. Dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC) are introduced into dental materials for their antimicrobial and protein-repellent properties. This study investigates the effects of incorporating dimethylaminohexadecyl methacrylate (DMAHDM) and 2-methacryloyloxyethyl phosphorylcholine (MPC) into heat-polymerized (HP) and 3D-printed (3DP) denture base resins on microbial adhesion and cytotoxicity. Methods: HP and 3DP denture base specimens were prepared using varying concentrations of DMAHDM and MPC. Microbial adhesion was quantified using CFU counts of C. albicans, and cytotoxicity was assessed via an MTT assay using fibroblast cells after 24 h, 3 days, and 7 days. Results: Both DMAHDM and MPC significantly reduced the CFU counts in both HP and 3DP materials; the combination of 1.5% DMAHDM and 3% MPC exhibited the most substantial antimicrobial effects. Cytotoxicity results varied between materials and time points; however, all treated groups maintained cell viability above the 70% threshold, indicating no significant cytotoxic effects. Conclusion: Incorporating DMAHDM and MPC into denture base resins can effectively reduce microbial adhesion while maintaining acceptable cytotoxicity levels. Full article

(This article belongs to the Section Polymer Composites and Nanocomposites)

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25 pages, 7471 KiB

Open AccessArticle

Multiscale Numerical Study of Enhanced Ductility Ratios and Capacity in Carbon Fiber-Reinforced Polymer Concrete Beams for Safety Design

by Moab Maidi, Gili Lifshitz Sherzer and Erez Gal

Polymers 2025, 17(2), 234; https://doi.org/10.3390/polym17020234 - 17 Jan 2025

Viewed by 453

Abstract

Rigid reinforced concrete (RC) frames are generally adopted as stiff elements to make the building structures resistant to seismic forces. However, a method has yet to be fully sought to provide earthquake resistance through optimizing beam and column performance in a rigid frame. [...] Read more.

Rigid reinforced concrete (RC) frames are generally adopted as stiff elements to make the building structures resistant to seismic forces. However, a method has yet to be fully sought to provide earthquake resistance through optimizing beam and column performance in a rigid frame. Due to its high corrosion resistance, the integration of CFRP offers an opportunity to reduce frequent repairs and increase durability. This paper presents the structural response of CFRP beams integrated into rigid frames when subjected to seismic events. Without any design provision for CFRP systems in extreme events, multiscale simulations and parametric analyses were performed to optimize the residual state and global performance. Macroparameters, represented by the ductility ratio and microfactors, have been analyzed using a customized version of the modified compression field theory (MCFT). The main parameters considered were reinforcement under tension and compression, strength of concrete, height-to-width ratio, section cover, and confinement level, all of which are important to understand their influence on seismic performance. The parametric analysis results highlight the increased ductility and higher load-carrying capacity of the CFRP-reinforced tested component compared to the RC component. These results shed light on the possibility of designing CFRP-reinforced concrete components that could improve ductile frames with increased energy dissipation and be suitable for applications in non-corrosive seismic-resistant buildings. This also shows reduced brittleness and enhancement in the failure mode. Numerical simulations and experimental results showed a strong correlation with a deviation of about 8.3%, underlining the reliability of the proposed approach for designing seismic-resistant CFRP-reinforced structures. Full article

(This article belongs to the Special Issue Modeling of Polymer Composites and Nanocomposites)

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25 pages, 7109 KiB

Open AccessReview

Research Progress on Quantum Dot-Embedded Polymer Films and Plates for LCD Backlight Display

by Bin Xu, Jiankang Zhou, Chengran Zhang, Yunfu Chang and Zhengtao Deng

Polymers 2025, 17(2), 233; https://doi.org/10.3390/polym17020233 - 17 Jan 2025

Viewed by 573

Abstract

Abstract: Quantum dot–polymer composites have the advantages of high luminescent quantum yield (PLQY), narrow emission half-peak full width (FWHM), and tunable emission spectra, and have broad application prospects in display and lighting fields. Research on quantum dots embedded in polymer films and plates [...] Read more.

Abstract: Quantum dot–polymer composites have the advantages of high luminescent quantum yield (PLQY), narrow emission half-peak full width (FWHM), and tunable emission spectra, and have broad application prospects in display and lighting fields. Research on quantum dots embedded in polymer films and plates has made great progress in both synthesis technology and optical properties. However, due to the shortcomings of quantum dots, such as cadmium selenide (CdSe), indium phosphide (InP), lead halide perovskite (LHP), poor water, oxygen, and light stability, and incapacity for large-scale synthesis, their practical application is still restricted. Various polymers, such as methyl methacrylate (PMMA), polyethylene terephthalate (PET), polystyrene (PS), polyvinylidene fluoride (PVDF), polypropylene (PP), etc., are widely used in packaging quantum dot materials because of their high plasticity, simple curing, high chemical stability, and good compatibility with quantum dot materials. This paper focuses on the application and development of quantum dot–polymer materials in the field of backlight displays, summarizes and expounds the synthesis strategies, advantages, and disadvantages of different quantum dot–polymer materials, provides inspiration for the optimization of quantum dot–polymer materials, and promotes their application in the field of wide-color-gamut backlight display. Full article

(This article belongs to the Special Issue Polymers/Their Hybrid Materials for Optoelectronic Applications)

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25 pages, 10071 KiB

Open AccessArticle

Numerical Simulation of Airflow Organization in Vulcanization Tanks for Waste Tires

by Tianxi Su, Yongzhi Ma, Baolin Wang, Xiaowen Luan, Hui Li and Xuelong Zhang

Polymers 2025, 17(2), 232; https://doi.org/10.3390/polym17020232 - 17 Jan 2025

Viewed by 422

Abstract

Currently, in the domestic practice of retreading tires using vulcanization tanks, some tanks exhibit uneven temperature distributions leading to low retreading success rates. To address that, this paper simulated the temperature and velocity fields during the heating process of vulcanization tanks for waste [...] Read more.

Currently, in the domestic practice of retreading tires using vulcanization tanks, some tanks exhibit uneven temperature distributions leading to low retreading success rates. To address that, this paper simulated the temperature and velocity fields during the heating process of vulcanization tanks for waste tire retreading. The results indicated that a higher heating power reduces the time required for the vulcanizing agent to reach the vulcanization condition, but it also increases the difference in tire temperature in the tank, with a severely uneven distribution of the temperature field. Subsequently, to improve the uniformity of temperature distribution and enhance the retreading rate of waste tires, this paper proposed two types of orifice plates to adjust the airflow organization. The results show that both the plain orifice plate and the frustum cone orifice plate can enhance the uniformity of the temperature field within the vulcanization tank and reduce the temperature difference between tires. Moreover, at the same heating power, the presence of the orifice plates increases the rate of temperature increase in the tires and the vulcanizing agent compared to the original vulcanization tank, improving the thermal efficiency of the vulcanization tank heater. Full article

(This article belongs to the Special Issue Polymer-Based Flexible Materials, 2nd Edition)

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14 pages, 3904 KiB

Open AccessArticle

Enhancing the Mechanical and Adhesive Properties of Polyurethane Adhesives with Propylene Oxide-Modified Ethylenediamine (PPO-EDA)

by Nam Gyu Jang, Tran Quang Linh, Mai Toan, Kiok Kwon and Seunghan Shin

Polymers 2025, 17(2), 231; https://doi.org/10.3390/polym17020231 - 17 Jan 2025

Viewed by 467

Abstract

This study explores the use of propylene oxide-modified ethylenediamine (PPO-EDA) as a novel crosslinker and chain extender in polyurethane (PU) adhesives. PPO-EDA was synthesized and compared with N,N’-dimethylethylenediamine (DMEDA) to assess its impact on mechanical properties and adhesion performance. Key [...] Read more.

This study explores the use of propylene oxide-modified ethylenediamine (PPO-EDA) as a novel crosslinker and chain extender in polyurethane (PU) adhesives. PPO-EDA was synthesized and compared with N,N’-dimethylethylenediamine (DMEDA) to assess its impact on mechanical properties and adhesion performance. Key parameters such as NCO conversion, tensile strength, and lap shear strength were thoroughly evaluated. The results demonstrated that incorporating PPO-EDA significantly improved NCO conversion and crosslink density, leading to notable enhancements in tensile strength and elastic modulus compared to DMEDA. Lap shear tests further revealed superior adhesion performance in PPO-EDA-modified PU adhesives, particularly on amine silane-treated steel substrates, where lap shear strength consistently outperformed other samples. This improved performance was attributed to PPO-EDA’s dual role as a chain extender and crosslinker, which strengthened the adhesive’s structural integrity. This study underscores the effectiveness of PPO-EDA as a modifier for enhancing both mechanical and adhesive properties in PU-based adhesives, offering a promising solution for optimizing high-performance adhesives in automotive and industrial applications. Full article

(This article belongs to the Section Polymer Processing and Engineering)

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17 pages, 2512 KiB

Open AccessArticle

Multifunctional Biological Performance of Electrospun PCL Scaffolds Formulated with Silver Sulfide Nanoparticles

by María del Carmen Torres-Pedroza, Ariadna Fernanda Martínez-Ávila, Karla Juarez-Moreno, Miriam Estevez, Lorena Álvarez-Contreras, Martha Elena Cruz-Soto, Lucero Granados-López, Noé Arjona and Beatriz Liliana España-Sánchez

Polymers 2025, 17(2), 230; https://doi.org/10.3390/polym17020230 - 17 Jan 2025

Viewed by 557

Abstract

Our work describes the green synthesis of silver sulfide nanoparticles (Ag₂S NPs) and their formulation into polycaprolactone fibers (PCL), aiming to improve the multifunctional biological performance of PCL membranes as scaffolds. For this purpose, an extract of rosemary (Salvia rosmarinus [...] Read more.

Our work describes the green synthesis of silver sulfide nanoparticles (Ag₂S NPs) and their formulation into polycaprolactone fibers (PCL), aiming to improve the multifunctional biological performance of PCL membranes as scaffolds. For this purpose, an extract of rosemary (Salvia rosmarinus) was employed as a reducing agent for the Ag₂S NPs, obtaining irregular NPs and clusters of 5–60 nm, with a characteristic SPR absorption at 369 nm. Ag₂S was successfully incorporated into PCL fibers by electrospinning using heparin (HEP) as a stabilizer/biocompatibility agent, obtaining nanostructured fibers with a ca. 500–800 nm diameter. Different amounts of Ag₂S NPs (0.05, 0.5, and 1 wt.%) enhanced the nanostructured membranes’ surface polarity and mechanical performance, with a controlled ion release after 6 days submerged in PBS solution, determined by cyclic voltammetry. As a result, PCL/HEP/Ag₂S scaffolds exhibit high antibacterial performance (80–90%) at early stages of contact (3 h) against E. coli and S. aureus. Also, cytotoxicity analysis demonstrated that the nanostructured membranes are biocompatible and exhibit high fibroblast cell regeneration, which is optimal for their application as scaffolds. To validate the regenerative response of PCL/HEP/Ag₂S scaffolds, controlled wounds were induced in Wistar rats, presenting a favorable healing response by contact with PCL/HEP/Ag₂S 1%, compared with the untreated wound. Our results indicated that nanostructured scaffolds enable the development of novel nanomaterials with multifunctional biological performance. Full article

(This article belongs to the Special Issue Functional and Biocompatible Nanostructured Polymer Scaffolds for Therapeutic Applications)

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22 pages, 6160 KiB

Open AccessArticle

Preparation and Performance Research of Pb(II)-Imprinted Acrylonitrile-Co-Acrylic Acid Composite Material with Modified Sand Particles as Carrier

by Yixin Sui, Shuaibing Gao, Jiaxiang Qi, Shawket Abliz and Linlin Chai

Polymers 2025, 17(2), 229; https://doi.org/10.3390/polym17020229 - 17 Jan 2025

Viewed by 502

Abstract

Lead (Pb) is classified as a prevalent metallic pollutant, significantly impacting the ecological environment, especially human health. Consequently, it is crucial to develop adsorbent materials that are environmentally friendly, cost-effective, and which possess high selectivity. This study aims to fabricate a Pb(II)-imprinted acrylonitrile-co-acrylic [...] Read more.

Lead (Pb) is classified as a prevalent metallic pollutant, significantly impacting the ecological environment, especially human health. Consequently, it is crucial to develop adsorbent materials that are environmentally friendly, cost-effective, and which possess high selectivity. This study aims to fabricate a Pb(II)-imprinted acrylonitrile-co-acrylic acid composite material by using modified sand particles as the carrier, and then to investigate its properties. Through pretreatment of sand particles, acrylonitrile and acrylic acid were polymerized on the surface of modified sand particles, and Pb(II) served as a template ion for imprinting. A variety of characterization methods were used to verify the composite material and conduct an analysis of its morphology, chemical composition, and pore characteristics. The adsorption efficiency of this composite material for Pb(II) is comprehensively explored, with the process involving adsorption kinetics, adsorption isotherms, selective adsorption, and reuse experiments. Through static adsorption experiments, multiple elements influencing the adsorption ability of the composite material towards Pb(II) are investigated. It was demonstrated by the results that the composite material prepared possesses a rich pore structure and excellent Pb(II) recognition ability. The investigation on adsorption kinetics is in line with the quasi-first-order and quasi-second-order kinetic models, while the adsorption isotherm, obeys the Langmuir model. The ideal adsorption conditions were pH = 7, with the adsorption reaching equilibrium within 105 min. Even when multiple interfering ions were present, it still had high selectivity for Pb(II). The composite material showed an adsorption saturation capability reaching 41.83 mg·g⁻¹, considerably surpassing the non-imprinted counterpart. After being reused eight times, the composite material can still maintain an adsorption efficiency for Pb(II) that is above 79% and demonstrates high potential in the practical application environment. Full article

(This article belongs to the Special Issue Recent Advances in Molecularly Imprinted Polymers and Emerging Polymeric Technologies for Hazardous Compounds)

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14 pages, 6649 KiB

Open AccessArticle

Molecular Dynamics Study of Polyacrylamide and Polysaccharide-Derived Flocculants Adsorption on Mg(OH)₂ Surfaces at pH 11

by Gonzalo R. Quezada, Antonia A. Vargas, Steven Nieto, Karien I. García, Pedro Robles and Ricardo I. Jeldres

Polymers 2025, 17(2), 227; https://doi.org/10.3390/polym17020227 - 17 Jan 2025

Viewed by 651

Abstract

Brucite (Mg(OH)₂) is a typical precipitate in the mining industry that adversely affects processes such as flotation and thickening. Gaining insights into the physicochemical properties of this mineral is critical for developing strategies to mitigate these challenges and improve operational efficiency. [...] Read more.

Brucite (Mg(OH)₂) is a typical precipitate in the mining industry that adversely affects processes such as flotation and thickening. Gaining insights into the physicochemical properties of this mineral is critical for developing strategies to mitigate these challenges and improve operational efficiency. Additionally, incorporating natural-origin polymers aligns with the shift toward more sustainable mining practices. In this study, molecular dynamics simulations were employed to investigate the interaction of brucite with polysaccharides such as cellulose, guar gum, and alginate and to compare these with conventional polymers, including polyacrylamide, hydrolyzed polyacrylamide, and polyacrylic acid, under conditions of pH 11 in low-salinity water. The methodology enhanced adsorption sampling by incorporating additional temporary interactions between the polymer and the brucite surface. The results reveal that neutral polymers exhibit stronger and more stable interactions with brucite compared to charged polymers, which is consistent with the neutral nature of brucite under the studied conditions. Van der Waals forces predominantly govern the adsorption of polysaccharides, while Coulombic forces primarily drive interactions involving polyacrylamides. These findings provide valuable insights into the molecular mechanisms of polymer-brucite interactions, facilitating the development of more effective and sustainable mining additives. Full article

(This article belongs to the Special Issue Designing Polymers for Emerging Applications)

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28 pages, 14719 KiB

Open AccessArticle

Pequi Pulp (Caryocar brasiliense) Oil-Loaded Emulsions as Cosmetic Products for Topical Use

by Tácio Fragoso Pereira, Huelinton Borchardt, Wvandson F. Wanderley, Ulrich Vasconcelos and Itamara F. Leite

Polymers 2025, 17(2), 226; https://doi.org/10.3390/polym17020226 - 17 Jan 2025

Viewed by 744

Abstract

The pequi (Caryocar brasiliense) is a typical fruit from the Brazilian Cerrado. From it, pequi pulp oil is extracted, a valuable product for cosmetic applications due to its high levels of unsaturated fatty acids and carotenoids. Carotenoids are antioxidant compounds that [...] Read more.

The pequi (Caryocar brasiliense) is a typical fruit from the Brazilian Cerrado. From it, pequi pulp oil is extracted, a valuable product for cosmetic applications due to its high levels of unsaturated fatty acids and carotenoids. Carotenoids are antioxidant compounds that are easily oxidized. To improve pulp stability, emulsification techniques with carboxymethylcellulose at 1% (w/w) were used to encapsulate the pequi pulp oil at 1, 3, 5% (w/w), and 8% (w/w) of polysorbate 80^® using a high-rotation mechanical stirrer. The pequi pulp oil was first characterized by FTIR and GC-MS. The results indicated the presence of chemical groups characteristic of the oil itself and the presence of a large proportion of fatty acids, which are essential for the maintenance of cutaneous hydration and the barrier, also acting in the tissue repair process. All emulsions presented stable over 120 days with slightly acidic pH values and were compatible with human skin. The droplet diameter was less than 330 nm, and the polydispersity index was around 0.3, indicating systems with low polydispersity. The Zeta potential (ζ) exhibited negative values sufficient to stabilize the emulsified systems. All emulsions behaved as non-Newtonian fluids, presenting pseudo-plastic and thixotropic properties that are considered important for topical applications. Full article

(This article belongs to the Special Issue Biopolymer Matrices for Incorporation of Bioactive Compounds)

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