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13 pages, 4450 KiB

Open AccessArticle

One-Shot Fabrication of Polymeric Hollow Microneedles by Standard Photolithography

by Principia Dardano, Selene De Martino, Mario Battisti, Bruno Miranda, Ilaria Rea and Luca De Stefano

Polymers 2021, 13(4), 520; https://doi.org/10.3390/polym13040520 - 9 Feb 2021

Cited by 43 | Viewed by 4542

Abstract

Microneedles (MNs) are an emerging technology in pharmaceutics and biomedicine, and are ready to be commercialized in the world market. However, solid microneedles only allow small doses and time-limited administration rates. Moreover, some well-known and already approved drugs need to be re-formulated when [...] Read more.

Microneedles (MNs) are an emerging technology in pharmaceutics and biomedicine, and are ready to be commercialized in the world market. However, solid microneedles only allow small doses and time-limited administration rates. Moreover, some well-known and already approved drugs need to be re-formulated when supplied by MNs. Instead, hollow microneedles (HMNs) allow for rapid, painless self-administrable microinjection of drugs in their standard formulation. Furthermore, body fluids can be easily extracted for analysis by a reverse use of HMNs, thus making them perfect for sensing issues and theranostics applications. The fabrication of HMNs usually requires several many-step processes, increasing the costs and consequently decreasing the commercial interest. Photolithography is a well-known fabrication technique in microelectronics and microfluidics that fabricates MNs. In this paper, authors show a proof of concept of a patented, easy and one-shot fabrication of two kinds of HMNs: (1) Symmetric HMNs with a “volcano” shape, made by using a photolithographic mask with an array of transparent symmetric rings; and (2) asymmetric HMNs with an oblique aperture, like standard hypodermic steel needles, made by using an array of transparent asymmetric rings, defined by two circles, which centers are slightly mismatched. Simulation of light propagation, fabrication process, and preliminary results on ink microinjection are presented. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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16 pages, 6705 KiB

Open AccessArticle

Preparation and Performance of Supercritical Carbon Dioxide Thickener

by Bin Liu, Yanling Wang and Lei Liang

Polymers 2021, 13(1), 78; https://doi.org/10.3390/polym13010078 - 28 Dec 2020

Cited by 15 | Viewed by 3089

Abstract

The low sand-carrying problem caused by the low viscosity of supercritical carbon dioxide (SC–CO₂) limits the development of supercritical CO₂ fracturing technology. In this study, a molecular simulation method was used to design a fluorine-free solvent-free SC–CO₂ thickener 1,3,5,7-tetramethylcyclotetrasiloxane [...] Read more.

The low sand-carrying problem caused by the low viscosity of supercritical carbon dioxide (SC–CO₂) limits the development of supercritical CO₂ fracturing technology. In this study, a molecular simulation method was used to design a fluorine-free solvent-free SC–CO₂ thickener 1,3,5,7-tetramethylcyclotetrasiloxane (HBD). Simulations and experiments mutually confirm that HBD-1 and HBD-2 have excellent solubility in SC–CO₂. The apparent viscosity of SC–CO₂ after thickening was evaluated with a self-designed and assembled capillary viscometer. The results show that when the concentration of HBD-2 is 5 wt.% (305.15 K, 10 MPa), the viscosity of SC–CO₂ increases to 4.48 mPa·s. Combined with the capillary viscometer and core displacement device, the low damage of SC–CO₂ fracturing fluid to the formation was studied. This work solves the pollution problems of fluoropolymers and co-solvents to organisms and the environment and provides new ideas for the molecular design and research of SC–CO₂ thickeners. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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16 pages, 20156 KiB

Open AccessArticle

In Vitro and In Vivo Biosafety Analysis of Resorbable Polyglycolic Acid-Polylactic Acid Block Copolymer Composites for Spinal Fixation

by Seung Kyun Yoon, Jin Ho Yang, Hyun Tae Lim, Young-Wook Chang, Muhammad Ayyoob, Xin Yang, Young Jun Kim, Han-Seung Ko, Jae Young Jho and Dong June Chung

Polymers 2021, 13(1), 29; https://doi.org/10.3390/polym13010029 - 23 Dec 2020

Cited by 11 | Viewed by 3401

Abstract

Herein, spinal fixation implants were constructed using degradable polymeric materials such as PGA–PLA block copolymers (poly(glycolic acid-b-lactic acid)). These materials were reinforced by blending with HA-g-PLA (hydroxyapatite-graft-poly lactic acid) and PGA fiber before being tested to confirm its biocompatibility via in vitro (MTT [...] Read more.

Herein, spinal fixation implants were constructed using degradable polymeric materials such as PGA–PLA block copolymers (poly(glycolic acid-b-lactic acid)). These materials were reinforced by blending with HA-g-PLA (hydroxyapatite-graft-poly lactic acid) and PGA fiber before being tested to confirm its biocompatibility via in vitro (MTT assay) and in vivo animal experiments (i.e., skin sensitization, intradermal intracutaneous reaction, and in vivo degradation tests). Every specimen exhibited suitable biocompatibility and biodegradability for use as resorbable spinal fixation materials. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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13 pages, 3964 KiB

Open AccessArticle

Recycling and Reprocessing of Thermoplastic Polyurethane Materials towards Nonwoven Processing

by Bastian Wölfel, Andreas Seefried, Vincent Allen, Joachim Kaschta, Christopher Holmes and Dirk W. Schubert

Polymers 2020, 12(9), 1917; https://doi.org/10.3390/polym12091917 - 25 Aug 2020

Cited by 30 | Viewed by 13361

Abstract

Thermoplastic Polyurethane (TPU) is a unique tailorable material due to the interactions of hard and soft segments within the block-copolymer chain. Therefore, various products can be created out of this material. A general trend towards a circular economy with regards to sustainability in [...] Read more.

Thermoplastic Polyurethane (TPU) is a unique tailorable material due to the interactions of hard and soft segments within the block-copolymer chain. Therefore, various products can be created out of this material. A general trend towards a circular economy with regards to sustainability in combination with TPU being comparably expensive is of high interest to recycle production as well as post-consumer wastes. A systematic study investigating the property changes of TPU is provided, focusing on two major aspects. The first aspect focuses on characterizing the change of basic raw material properties through recycling. Gel permeation chromatography (GPC) and processing load during extrusion indicate a decrease in molar mass and consequently viscosity with an increasing number of recycling cycles. This leads to a change in morphology at lower molar mass, characterized by differential scanning calorimetry (DSC) and visualized by atomic force microscope (AFM). The change in molar mass and morphology with increasing number of recycling cycles has an impact on the material performance under tensile stress. The second aspect describes processing of the recycled TPU to nonwoven fabrics utilizing melt blowing, which are evaluated with respect to relevant mechanical properties and related to molecular characteristics. The molar mass turns out to be the governing factor regarding mechanical performance and processing conditions for melt blown products. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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21 pages, 5541 KiB

Open AccessArticle

Synthesis and Characterization of Copoly(Ether Sulfone)s with Different Percentages of Diphenolic Acid Units

by Andrea A. Scamporrino, Concetto Puglisi, Angela Spina, Maurizio Montaudo, Daniela C. Zampino, Gianluca Cicala, Giulia Ognibene, Chiara Di Mauro, Sandro Dattilo, Emanuele F. Mirabella, Giuseppe Recca and Filippo Samperi

Polymers 2020, 12(8), 1817; https://doi.org/10.3390/polym12081817 - 13 Aug 2020

Cited by 8 | Viewed by 3535

Abstract

New functionalized Poly(ether sulfone)s having different molar ratio (10, 20, 30, 50, 70, 100 mol%) of 4,4-bis phenoxy pentanoic acid unit (diphenolic acid; DPA) units were synthesized and characterized by (¹H and ¹³C)-NMR, MALDI-TOF MS, FT-IR, DSC and DMA analyses. [...] Read more.

New functionalized Poly(ether sulfone)s having different molar ratio (10, 20, 30, 50, 70, 100 mol%) of 4,4-bis phenoxy pentanoic acid unit (diphenolic acid; DPA) units were synthesized and characterized by (¹H and ¹³C)-NMR, MALDI-TOF MS, FT-IR, DSC and DMA analyses. The microstructural analysis of the copolymers, obtained by ¹³C-NMR using an appropriate statistical model, shows a random distribution of copolymer sequences, as expected. The presence of different amount of DPA units along the polymer chains affects the chemical and physical properties of the copolymers. The Tg and the contact angle values decrease as the molar fraction of DPA units increases, whereas the hydrophilicity increases. NMR and MALDI-TOF MS analyses show that all polymer chains are almost terminated with hydroxyl and chlorine as end groups. The presence of cyclic oligomers was also observed by MALDI-TOF MS analysis. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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24 pages, 20053 KiB

Open AccessArticle

Thermal Degradation Processes of Aromatic Poly(Ether Sulfone) Random Copolymers Bearing Pendant Carboxyl Groups

by Sandro Dattilo, Concetto Puglisi, Emanuele Francesco Mirabella, Angela Spina, Andrea Antonino Scamporrino, Daniela Clotilde Zampino, Ignazio Blanco, Gianluca Cicala, Giulia Ognibene, Chiara Di Mauro and Filippo Samperi

Polymers 2020, 12(8), 1810; https://doi.org/10.3390/polym12081810 - 12 Aug 2020

Cited by 12 | Viewed by 4437

Abstract

Thermal degradation processes of poly(ether sulfone) random copolymers having different molar amount of diphenolic acid (DPA) units were studied by direct-pyrolysis/mass spectrometry, stepwise pyrolysis-gas chromatography/mass spectrometry and thermogravimetric techniques. Results highlighted that thermal degradation processes occur in the temperature range from 370 to [...] Read more.

Thermal degradation processes of poly(ether sulfone) random copolymers having different molar amount of diphenolic acid (DPA) units were studied by direct-pyrolysis/mass spectrometry, stepwise pyrolysis-gas chromatography/mass spectrometry and thermogravimetric techniques. Results highlighted that thermal degradation processes occur in the temperature range from 370 to 650 °C, yielding a char residue of 32–35 wt%, which decreases as the mol% of DPA units rises. The pyrolysis/mass spectra data allowed us to identify the thermal decomposition products and to deduce the possible thermal degradation mechanisms. Thermal degradation data suggest that the decarboxylation process of the pendant acid moiety mainly occurs in the initial step of the pyrolysis of the copolymers studied. Successively, the scission of the generated isobutyl groups occurs in the temperature range between 420 and 480 °C. Known processes involving the main chain random scission of the diphenyl sulfone and diphenyl ether groups were also observed. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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14 pages, 4635 KiB

Open AccessArticle

Syntheses of Colorless and Transparent Polyimide Membranes for Microfiltration

by Jong Won Kim and Jin-Hae Chang

Polymers 2020, 12(7), 1610; https://doi.org/10.3390/polym12071610 - 20 Jul 2020

Cited by 14 | Viewed by 3834

Abstract

Herein, poly(amic acid) (PAA) was synthesized using 4,4’-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) as a dianhydride and 2,2-bis(3-aminophenyl)hexafluoropropane (6FAm) and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAm-OH) as diamines. Poly(vinyl alcohol) (PVA) at various contents (0–5.0 wt%) was blended with PAA to prepare a composite material. Then, colorless and transparent [...] Read more.

Herein, poly(amic acid) (PAA) was synthesized using 4,4’-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) as a dianhydride and 2,2-bis(3-aminophenyl)hexafluoropropane (6FAm) and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAm-OH) as diamines. Poly(vinyl alcohol) (PVA) at various contents (0–5.0 wt%) was blended with PAA to prepare a composite material. Then, colorless and transparent polyimide (CPI) composite films were prepared by applying various stages of heat treatment using the PAA/PVA blend film as a precursor. These film-type composites were immersed in water to completely dissolve PVA, a water-soluble polymer, and their pore sizes were investigated to determine their potential as a porous membrane. According to the results of scanning electronic microscopy (SEM), as the concentration of PVA increased from 0 to 5.0 wt% in the CPI/PVA composite films, the size of the pores resulting from the dissolution of water-soluble PVA increased. Further, the micrometer-sized pores were uniformly dispersed in the CPI films. The thermal properties, morphology, and optical transparency of the two types of CPI membranes synthesized using 6FAm and 6FAm-OH monomers were examined and compared. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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13 pages, 4360 KiB

Open AccessArticle

Stress-Softening in Particle-Filled Polyurethanes under Cyclic Compressive Loading

by Wenshuai Xu, Mangong Zhang, Yu Liu, Hao Zhang, Meng Chen, Heng Jiang and Yuren Wang

Polymers 2020, 12(7), 1588; https://doi.org/10.3390/polym12071588 - 17 Jul 2020

Cited by 7 | Viewed by 3137

Abstract

Elastomer compositions containing various particulate fillers can be formulated according to the specific functions required of them. Stress softening—which is also known as the Mullins effect—occurs during high loading and unloading paths in certain supramolecular elastomer materials. Previous experiments have revealed that the [...] Read more.

Elastomer compositions containing various particulate fillers can be formulated according to the specific functions required of them. Stress softening—which is also known as the Mullins effect—occurs during high loading and unloading paths in certain supramolecular elastomer materials. Previous experiments have revealed that the load–displacement response differs according to the filler used, demonstrating an unusual model of correspondence between the constitutive materials. Using a spherical indentation method and numerical simulation, we investigated the Mullins effect on polyurethane (PU) compositions subjected to cyclic uniaxial compressive load. The PU compositions comprised rigid particulate fillers (i.e., nano-silica and carbon black). The neo-Hooke model and the Ogden–Roxburgh Mullins model were used to describe the nonlinear deformation behavior of the soft materials. Based on finite element methods and parameter optimization, the load–displacement curves of various filled PUs were analyzed and fitted, enabling constitutive parameter prediction and inverse modeling. Hence, correspondence relationships between material components and constitutive parameters were established. Such relationships are instructive for the preparation of materials with specific properties. The method described herein is a more quantitative approach to the formulation of elastomer compositions comprising particulate fillers. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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17 pages, 6906 KiB

Open AccessArticle

Structural Insights of Humins/Epoxidized Linseed Oil/ Hardener Terpolymerization

by Erol Licsandru, Marc Gaysinski and Alice Mija

Polymers 2020, 12(7), 1583; https://doi.org/10.3390/polym12071583 - 16 Jul 2020

Cited by 12 | Viewed by 3284

Abstract

Bio-based thermosetting resins were synthesized from a ternary composition: humins; epoxidized linseed oil (ELO); and an industrial hardener, Capcure3-800 (CAP). Humins are in a focused attention in the last years, as biorefinery by-product, therefore its valorization through materials design is very important. Here [...] Read more.

Bio-based thermosetting resins were synthesized from a ternary composition: humins; epoxidized linseed oil (ELO); and an industrial hardener, Capcure3-800 (CAP). Humins are in a focused attention in the last years, as biorefinery by-product, therefore its valorization through materials design is very important. Here we present a structural study of terpolymerization of humins/ ELO/CAP. The reactivity of these systems was highlighted by in situ FT-IR and ¹H and ¹³C NMR. The integration of humins in thermosetting resins gives alternatives to new feedstocks for future bio-based materials. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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22 pages, 7166 KiB

Open AccessArticle

Structural, Impedance and Electrochemical Characteristics of Electrical Double Layer Capacitor Devices Based on Chitosan: Dextran Biopolymer Blend Electrolytes

by Shujahadeen B. Aziz, Muhamad H. Hamsan, Muaffaq M. Nofal, Wrya O. Karim, Iver Brevik, Mohamad. A. Brza, Rebar T. Abdulwahid, Shakhawan Al-Zangana and Mohd F. Z. Kadir

Polymers 2020, 12(6), 1411; https://doi.org/10.3390/polym12061411 - 24 Jun 2020

Cited by 39 | Viewed by 4375

Abstract

This report presents the preparation and characterizations of solid biopolymer blend electrolyte films of chitosan as cationic polysaccharide and anionic dextran (CS: Dextran) doped with ammonium iodide (NH₄I) to be utilized as electrolyte and electrode separator in electrical double-layer capacitor (EDLC) [...] Read more.

This report presents the preparation and characterizations of solid biopolymer blend electrolyte films of chitosan as cationic polysaccharide and anionic dextran (CS: Dextran) doped with ammonium iodide (NH₄I) to be utilized as electrolyte and electrode separator in electrical double-layer capacitor (EDLC) devices. FTIR and XRD techniques were used to study the structural behavior of the films. From the FTIR band analysis, shifting and broadening of the bands were observed with increasing salt concentration. The XRD analysis indicates amorphousness of the blended electrolyte samples whereby the peaks underwent broadening. The analysis of the impedance spectra emphasized that incorporation of 40 wt.% of NH₄I salt into polymer electrolyte exhibited a relatively high conductivity (5.16 × 10⁻³ S/cm). The transference number measurement (TNM) confirmed that ion (t_ion = 0.928) is the main charge carriers in the conduction process. The linear sweep voltammetry (LSV) revealed the extent of durability of the relatively high conducting film which was 1.8 V. The mechanism of charge storage within the fabricated EDLC has been explained to be fully capacitive behavior with no redox peaks appearance in the cyclic voltammogram (CV). From this findings, four important parameters of the EDLC; specific capacitance, equivalent series resistance, energy density and power density were calculated as 67.5 F/g, 160 ohm, 7.59 Wh/kg and 520.8 W/kg, respectively. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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11 pages, 1601 KiB

Open AccessArticle

Hyper-Crosslinked Polymer Nanocomposites Containing Mesoporous Silica Nanoparticles with Enhanced Adsorption Towards Polar Dyes

by Marco Guerritore, Rachele Castaldo, Brigida Silvestri, Roberto Avolio, Mariacristina Cocca, Maria Emanuela Errico, Maurizio Avella, Gennaro Gentile and Veronica Ambrogi

Polymers 2020, 12(6), 1388; https://doi.org/10.3390/polym12061388 - 20 Jun 2020

Cited by 15 | Viewed by 3374

Abstract

The development of new styrene-based hyper-crosslinked nanocomposites (HCLN) containing mesoporous silica nanoparticles (MSN) is reported here as a new strategy to obtain functional high surface area materials with an enhanced hydrophilic character. The HCLN composition, morphology and porous structure were analyzed using a [...] Read more.

The development of new styrene-based hyper-crosslinked nanocomposites (HCLN) containing mesoporous silica nanoparticles (MSN) is reported here as a new strategy to obtain functional high surface area materials with an enhanced hydrophilic character. The HCLN composition, morphology and porous structure were analyzed using a multi-technique approach. The HCLN displayed a high surface area (above 1600 m²/g) and higher microporosity than the corresponding hyper-crosslinked neat resin. The enhanced adsorption properties of the HCLN towards polar organic dyes was demonstrated through the adsorption of a reactive dye, Remazol Brilliant Blue R (RB). In particular, the HCLN containing 5phr MSN showed the highest adsorption capacity of RB. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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17 pages, 22725 KiB

Open AccessArticle

Effect of Fabric Architecture on Tensile Behaviour of the High-Molecular-Weight Polyethylene 3-Dimensional Interlock Composite Reinforcements

by Mengru Li, Peng Wang, François Boussu and Damien Soulat

Polymers 2020, 12(5), 1045; https://doi.org/10.3390/polym12051045 - 2 May 2020

Cited by 16 | Viewed by 3325

Abstract

As promising fibrous reinforcements in the thick composites manufacturing, 3-dimensional warp interlock fabrics (3DWIFs) are recognised more and more in the industry for their outstanding mechanical properties compared to the 2D laminates. The present work shows the influence of the fabric’s architecture on [...] Read more.

As promising fibrous reinforcements in the thick composites manufacturing, 3-dimensional warp interlock fabrics (3DWIFs) are recognised more and more in the industry for their outstanding mechanical properties compared to the 2D laminates. The present work shows the influence of the fabric’s architecture on the tensile behaviour of 3DWIFs. Five kinds of 3D fabrics with different interlock structures have been designed according to the main category of binding warp yarn evolution. These five 3DWIFs, containing both binding and stuffer warp yarns and produced with the same warp and weft densities, are experimentally tested via uniaxial tensile tests. The experimental results of the different 3DWIFs have been compared to find the optimal solution based on several mechanical performances. Fabric structures have an impact on tensile properties both in the warp and weft directions. Furthermore, other influential factors, for example, the yarn crimps during the weaving process and the crimp angles of binding warp yarns in 3DWIFs, are investigated and discussed in the paper. The influence of the total crimp angles related to the binding path on the tensile properties of 3DWIFs via the inter yarns friction is summarised. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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20 pages, 5445 KiB

Open AccessArticle

Contrasting Photo-Switching Rates in Azobenzene Derivatives: How the Nature of the Substituent Plays a Role

by Domenico Pirone, Nuno A. G. Bandeira, Bartosz Tylkowski, Emily Boswell, Regine Labeque, Ricard Garcia Valls and Marta Giamberini

Polymers 2020, 12(5), 1019; https://doi.org/10.3390/polym12051019 - 30 Apr 2020

Cited by 13 | Viewed by 5073

Abstract

A molecular design approach was used to create asymmetrical visible light-triggered azo-derivatives that can be good candidates for polymer functionalization. The specific electron–donor substituted molecules were characterized and studied by means of NMR analyses and UV-visible spectroscopy, comparing the results with Time Dependent [...] Read more.

A molecular design approach was used to create asymmetrical visible light-triggered azo-derivatives that can be good candidates for polymer functionalization. The specific electron–donor substituted molecules were characterized and studied by means of NMR analyses and UV-visible spectroscopy, comparing the results with Time Dependent Density Functional (TD-DFT) calculations. A slow rate of isomerization (k_i = 1.5 × 10⁻⁴ s⁻¹) was discovered for 4-((2-hydroxy-5methylphenyl) diazenyl)-3-methoxybenzoic acid (AZO1). By methylating this moiety, it was possible to unlock the isomerization mechanism for the second molecule, methyl 3-methoxy-4-((2-methoxy-5-methylphenyl) diazenyl)benzoate (AZO2), reaching promising isomerization rates with visible light irradiation in different solvents. It was discovered that this rate was heightened by one order of magnitude (k_i = 3.1 × 10⁻³ s⁻¹) for AZO2. A computational analysis using density functional (DFT/PBE0) and wavefunction (QD-NEVPT2) methodologies provided insight into the photodynamics of these systems. Both molecules require excitation to the second (S₂) excited state situated in the visible region to initiate the isomerization. Two classic mechanisms were considered, namely rotation and inversion, with the former being energetically more favorable. These azo-derivatives show potential that paves the way for future applications as building blocks of functional polymers. Likewise, they could be really effective for the modification of existing commercial polymers, thus transferring their stimuli responsive properties to polymeric bulky structures, converting them into smart materials. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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15 pages, 2207 KiB

Open AccessArticle

Bio-Based Epoxy Shape-Memory Thermosets from Triglycidyl Phloroglucinol

by David Santiago, Dailyn Guzmán, Francesc Ferrando, Àngels Serra and Silvia De la Flor

Polymers 2020, 12(3), 542; https://doi.org/10.3390/polym12030542 - 2 Mar 2020

Cited by 17 | Viewed by 4214

Abstract

A series of bio-based epoxy shape-memory thermosetting polymers were synthesized starting from a triglycidyl phloroglucinol (3EPOPh) and trimethylolpropane triglycidyl ether (TPTE) as epoxy monomers and a polyetheramine (JEF) as crosslinking agent. The evolution of the curing process was studied by differential scanning calorimetry [...] Read more.

A series of bio-based epoxy shape-memory thermosetting polymers were synthesized starting from a triglycidyl phloroglucinol (3EPOPh) and trimethylolpropane triglycidyl ether (TPTE) as epoxy monomers and a polyetheramine (JEF) as crosslinking agent. The evolution of the curing process was studied by differential scanning calorimetry (DSC) and the materials obtained were characterized by means of DSC, thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), stress-strain tests, and microindentation. Shape-memory properties were evaluated under free and totally constrained conditions. All results were compared with an industrial epoxy thermoset prepared from standard diglycidyl ether of Bisphenol A (DGEBA). Results revealed that materials prepared from 3EPOPh were more reactive and showed a tighter network with higher crosslinking density and glass transition temperatures than the prepared from DGEBA. The partial substitution of 3EPOPh by TPTE as epoxy comonomer caused an increase in the molecular mobility of the materials but without worsening the thermal stability. The shape-memory polymers (SMPs) prepared from 3EPOPh showed good mechanical properties as well as an excellent shape-memory performance. They showed almost complete shape-recovery and shape-fixation, fast shape-recovery rates, and recovery stress up to 7 MPa. The results obtained in this study allow us to conclude that the triglycidyl phloroglucinol derivative of eugenol is a safe and environmentally friendly alternative to DGEBA for preparing thermosetting shape-memory polymers. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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11 pages, 1528 KiB

Open AccessArticle

Synthesis and Thermal Characteristic of Liquid Crystalline Polyoxetane Containing Trans-Stilbene Side Group

by Li-Chuan Wu, Cheng-Chih Chen and Chih-Hung Lin

Polymers 2020, 12(1), 185; https://doi.org/10.3390/polym12010185 - 10 Jan 2020

Cited by 2 | Viewed by 2788

Abstract

A series of fourteen liquid crystalline monomers and polyoxetanes containing trans-biphenyl side group have been successfully synthesized. The thermal and mesomorphic properties of monomers (1M~14M) and polymers (1P~14P) are measured using DSC, POM, and X-ray. [...] Read more.

A series of fourteen liquid crystalline monomers and polyoxetanes containing trans-biphenyl side group have been successfully synthesized. The thermal and mesomorphic properties of monomers (1M~14M) and polymers (1P~14P) are measured using DSC, POM, and X-ray. All of the series monomers present enantiotropic smectic H and smectic G phase and the series polymers show enantiotropic smectic A phase which three polymers contained exhibit smectic E. Polyoxetanes have been used as a cationic ring-opening polymerization of oxetane monomers bearing a pendant trans-stilbene mesogenic unit including different spacer length and terminal alkyl length. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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10 pages, 4066 KiB

Open AccessArticle

Hydrophilic Porous Polydimethysiloxane Sponge as a Novel 3D Matrix Mimicking Heterogeneous Pores in Soil for Plant Cultivation

by Feng Chen, Huihui Chai, Zhaoxi Song, Ling Yu and Can Fang

Polymers 2020, 12(1), 140; https://doi.org/10.3390/polym12010140 - 6 Jan 2020

Cited by 4 | Viewed by 5185

Abstract

In this work, a citric acid monohydrate (CAM)-templated polydimethylsiloxane (PDMS) sponge was proposed to mimic heterogeneous pore structures in the soil for plant cultivation. The porosity of the PDMS sponges was tuned by adjusting the CAM template. The water intake capability of the [...] Read more.

In this work, a citric acid monohydrate (CAM)-templated polydimethylsiloxane (PDMS) sponge was proposed to mimic heterogeneous pore structures in the soil for plant cultivation. The porosity of the PDMS sponges was tuned by adjusting the CAM template. The water intake capability of the sponge was improved by (3-Aminopropyl) triethoxysilane (APTES) functionalization. The pore size and pore distribution were characterized by SEM and micro-computed tomography (micro-CT). The effect of pore structures on Oryzasativa (O. sativa) growth was investigated. Also, a 3D multi-layer PDMS sponge assembling was proposed to mimic the heterogeneous pore distribution at the different soil depth. The different growth rates of O. sativa and Nicotiana tabacum L. (N. tabacum) seeds on porous PDMS sponge indicated the impact of physical obstacles (pores) and chemical (water content) conditions on plant development. It is anticipated that this PDMS sponge could serve as a 3D matrix to mimic soil and provide a new idea for plant cultivation. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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Review

Jump to: Research

27 pages, 6235 KiB

Open AccessReview

Synthesis and Conductivity Studies of Poly(Methyl Methacrylate) (PMMA) by Co-Polymerization and Blending with Polyaniline (PANi)

by Helyati Abu Hassan Shaari, Muhammad Mahyiddin Ramli, Mohd Nazim Mohtar, Norizah Abdul Rahman and Azizan Ahmad

Polymers 2021, 13(12), 1939; https://doi.org/10.3390/polym13121939 - 11 Jun 2021

Cited by 31 | Viewed by 7286

Abstract

Poly(methyl methacrylate) (PMMA) is a lightweight insulating polymer that possesses good mechanical stability. On the other hand, polyaniline (PANi) is one of the most favorable conducting materials to be used, as it is easily synthesized, cost-effective, and has good conductivity. However, most organic [...] Read more.

Poly(methyl methacrylate) (PMMA) is a lightweight insulating polymer that possesses good mechanical stability. On the other hand, polyaniline (PANi) is one of the most favorable conducting materials to be used, as it is easily synthesized, cost-effective, and has good conductivity. However, most organic solvents have restricted potential applications due to poor mechanical properties and dispersibility. Compared to PANi, PMMA has more outstanding physical and chemical properties, such as good dimensional stability and better molecular interactions between the monomers. To date, many research studies have focused on incorporating PANi into PMMA. In this review, the properties and suitability of PANi as a conducting material are briefly reviewed. The major parts of this paper reviewed different approaches to incorporating PANi into PMMA, as well as evaluating the modifications to improve its conductivity. Finally, the polymerization condition to prepare PMMA/PANi copolymer to improve its conductivity is also discussed. Full article

(This article belongs to the Special Issue Advanced Polymer Based Materials: Production, Characterization and Applications)

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Advanced Polymer Based Materials: Production, Characterization and Applications

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