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11 pages, 3886 KiB

Open AccessArticle

Watered-Based Graphene Dispersion Stabilized by a Graft Co-Polymer for Electrically Conductive Screen Printing

by Fengfeng Zhao, Hui Quan, Shijun Zhang, Yihui Xu, Zheng Zhou, Guangxin Chen and Qifang Li

Polymers 2023, 15(2), 356; https://doi.org/10.3390/polym15020356 - 10 Jan 2023

Cited by 3 | Viewed by 1931

Abstract

Graphene conductive inks have attracted significant attention in recent years due to their high conductivity, corrosion resistance, and environmentally friendly nature. However, the dispersion of graphene in aqueous solution is still challenging. In this work, we synthesized an amphiphilic graft copolymer, polyvinyl alcohol-g-polyaniline [...] Read more.

Graphene conductive inks have attracted significant attention in recent years due to their high conductivity, corrosion resistance, and environmentally friendly nature. However, the dispersion of graphene in aqueous solution is still challenging. In this work, we synthesized an amphiphilic graft copolymer, polyvinyl alcohol-g-polyaniline (PVA-g-PANI), and studied the graphene dispersion prepared with the graft copolymer by high-speed shear dispersion. The amphiphilic graft copolymer can be used as a stabilizer and adhesive agent in graphene dispersion. Given the steric hindrance of the graft copolymer, the stability of graphene dispersion is improved by decreasing the probability of π–π stacking. PVA-g-PANI has a better stability on graphene dispersion than carboxymethylcellulose sodium (CMC-Na) and a mixture of PVA and PANI. The graft copolymer has only a slight effect on the conductivity of graphene dispersion due to the existence of conductive PANI, which is beneficial for preparing the graphene dispersion with good conductivity and adhesion. Graphene dispersion is well-adapted to screen printing and is very stable with regard to the sheet resistance bending cycle. Full article

(This article belongs to the Special Issue Graphene-Based Polymer Composites and Their Applications)

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14 pages, 2995 KiB

Open AccessArticle

Synergistic Membrane Disturbance Improves the Antibacterial Performance of Polymyxin B

by Wenwen Li, Che Zhang, Xuemei Lu, Shuqing Sun, Kai Yang and Bing Yuan

Polymers 2022, 14(20), 4316; https://doi.org/10.3390/polym14204316 - 14 Oct 2022

Viewed by 1623

Abstract

Drug-resistant Gram-negative bacteria pose a serious threat to public health, and polymyxin B (PMB) is clinically used as a last-line therapy for the treatment of infections caused by these pathogens. However, the appearance of PMB resistance calls for an effort to develop new [...] Read more.

Drug-resistant Gram-negative bacteria pose a serious threat to public health, and polymyxin B (PMB) is clinically used as a last-line therapy for the treatment of infections caused by these pathogens. However, the appearance of PMB resistance calls for an effort to develop new approaches to improve its antibacterial performance. In this work, a new type of nanocomposite, composed of PMB molecules being chemically decorated on the surface of graphene oxide (GO) nanosheets, was designed, which showed potent antibacterial ability through synergistically and physically disturbing the bacterial membrane. The as-fabricated PMB@GO nanocomposites demonstrated an enhanced bacterial-killing efficiency, with a minimum inhibitory concentration (MIC) value half of that of free PMB (with an MIC value as low as 0.5 μg mL⁻¹ over Escherichia coli), and a bacterial viability less than one fourth of that of PMB (with a bacterial reduction of 60% after 3 h treatment, and 90% after 6 h incubation). Furthermore, the nanocomposite displayed moderate cytotoxicity or hemolysis effect, with cellular viabilities over 85% at concentrations up to 16 times the MIC value. Studies on antibacterial mechanism revealed that the synergy between PMB molecules and GO nanosheets greatly facilitated the vertical insertion of the nanocomposite into the lipid membrane, leading to membrane disturbance and permeabilization. Our results demonstrate a physical mechanism for improving the antibacterial performance of PMB and developing advanced antibacterial agents for better clinic uses. Full article

(This article belongs to the Special Issue Graphene-Based Polymer Composites and Their Applications)

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13 pages, 3706 KiB

Open AccessArticle

Fabrication of Graphene-Modified Styrene–Acrylic Emulsion by In Situ Aqueous Polymerization

by Yalin Li, Jieling Luo, Baoquan Huang, Hongjun Jin, Xiaoli Sun, Changlin Cao, Qinghua Chen and Qingrong Qian

Polymers 2022, 14(18), 3763; https://doi.org/10.3390/polym14183763 - 8 Sep 2022

Cited by 7 | Viewed by 2797

Abstract

With the aim of developing green coatings, styrene–acrylic emulsion has been widely used in architectural coatings due to its excellent environmental protection and energy conservation. Nevertheless, the lack of water and oxygen resistance of water-based styrofoam coatings has promoted various nanomaterials being studied [...] Read more.

With the aim of developing green coatings, styrene–acrylic emulsion has been widely used in architectural coatings due to its excellent environmental protection and energy conservation. Nevertheless, the lack of water and oxygen resistance of water-based styrofoam coatings has promoted various nanomaterials being studied for modification. To improve the performance of waterborne styrofoam coating, we introduced the graphene nanopowder and expected to enable it with the function of electromagnetic interference (EMI) shielding to reduce the damage of electromagnetic radiation. In this paper, the problem of poor interface compatibility between graphene and polymer resin was successfully addressed by in situ polymerization. In the process of pre-polymerization of styrene–acrylic emulsion monomer, graphene-modified styrene–acrylic emulsion was obtained by introducing graphene aqueous dispersion. The results showed that the styrene–acrylic emulsion with 4 wt% aqueous graphene dispersions exhibited the best dispersion stability, improved water and oxygen resistance, and the conductivity reached 1.89 × 10⁻² S/cm. Then, the graphene-modified coating for building was prepared by using graphene-modified styrofoam emulsion. All the performance indexes of the coating are in line with the industry standards, and it still showed benign EMI shielding effect even when the graphene content was low. It is demonstrated that in situ polymerization technology and the application of graphene in resin coatings modification will promote the development of green coatings. Full article

(This article belongs to the Special Issue Graphene-Based Polymer Composites and Their Applications)

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10 pages, 2966 KiB

Open AccessArticle

Study on Thermal Conductivity of P-Phenylenediamine Modified Graphene/Epoxy Composites

by Jun Lin, Jiancheng Zhou, Mengyao Guo, Danqing Chen and Guohua Chen

Polymers 2022, 14(17), 3660; https://doi.org/10.3390/polym14173660 - 3 Sep 2022

Cited by 5 | Viewed by 1900

Abstract

Thermal management has become an important requirement for many types of electrical equipment due to the development of integrated circuits. In this study, modified and reduced graphene fillers were synthesized in two steps, and then epoxy resin was filled through the evaporation of [...] Read more.

Thermal management has become an important requirement for many types of electrical equipment due to the development of integrated circuits. In this study, modified and reduced graphene fillers were synthesized in two steps, and then epoxy resin was filled through the evaporation of the solvent. The interfacial thermal resistance between the filler and matrix material was lowered by including amino groups to improve graphene compatibility in the epoxy resin. Furthermore, the reduction procedure was shown to have the potential to fix graphene oxide flaws, thereby improving thermal stability, electrical conductivity, and thermal conductivity of the composites. As a result, the thermal conductivity of the composite reached 1.7 W/mK, which is 750% higher than that of pure epoxy resin, and it was still insulated. Full article

(This article belongs to the Special Issue Graphene-Based Polymer Composites and Their Applications)

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10 pages, 2610 KiB

Open AccessArticle

Design and Preparation of Localized Heat-Resistant Coating

by Zaiming Lin, Yihan Chen, Zhuang Ma, Lihong Gao, Wenhua Chen, Guohua Chen and Chen Ma

Polymers 2022, 14(15), 3032; https://doi.org/10.3390/polym14153032 - 27 Jul 2022

Cited by 4 | Viewed by 2595

Abstract

Localized heat sources, such as flame guns and high-energy lasers, can cause severe damage to conventional materials. In this study, a novel localized heat-resistant coating with a high in-plane thermal conductivity was designed and prepared. Reduced graphene oxide (rGO) effectively improved the in-plane [...] Read more.

Localized heat sources, such as flame guns and high-energy lasers, can cause severe damage to conventional materials. In this study, a novel localized heat-resistant coating with a high in-plane thermal conductivity was designed and prepared. Reduced graphene oxide (rGO) effectively improved the in-plane thermal conductivity of the polyvinyl alcohol (PVA) film, while maintaining the thermal insulation of the resin matrix in the through-plane direction. This characteristic of the rGO/PVA film was combined with the thermal insulation of boron-modified phenolic resin (BPF), and the prepared composite coating with two layers of rGO/PVA films effectively lowered the back-surface temperature in the flame ablation test from 151 to 107 °C. In addition, the area of the ablation-affected region of coating was increased to 103.6 cm² from 31.9 cm², indicating an excellent heat transfer performance. The layer-by-layer structure could realize the compatibility of high in-plane thermal conductivity and good through-plane thermal insulation. The synergy of these two different characteristics is demonstrated to be the key to improving the localized heat-resistant performance of the composite coating. This study effectively expands the application range of high-conductive film, and the obtained coating could act as a shield against butane flame, high energy lasers, and other localized heat. Full article

(This article belongs to the Special Issue Graphene-Based Polymer Composites and Their Applications)

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12 pages, 18457 KiB

Open AccessArticle

Electronic Structure and External Electric Field Modulation of Polyethylene/Graphene Interface

by Hongfei Li, Zhaoming Qu, Yazhou Chen, Linsen Zhou and Yan Wang

Polymers 2022, 14(14), 2949; https://doi.org/10.3390/polym14142949 - 21 Jul 2022

Cited by 2 | Viewed by 2125

Abstract

Polymer nanocomposites can serve as promising electrostatic shielding materials; however, the underlying physical mechanisms governing the carrier transport properties between nanofillers and polymers remain unclear. Herein, the structural and electronic properties of two polyethylene/graphene (PE/G) interfaces, i.e., type-H and type-A, have been systematically [...] Read more.

Polymer nanocomposites can serve as promising electrostatic shielding materials; however, the underlying physical mechanisms governing the carrier transport properties between nanofillers and polymers remain unclear. Herein, the structural and electronic properties of two polyethylene/graphene (PE/G) interfaces, i.e., type-H and type-A, have been systematically investigated under different electric fields using first principle calculations. The results testify that the bandgaps of 128.6 and 67.8 meV are opened at the Dirac point for type-H and type-A PE/G interfaces, respectively, accompanied by an electron-rich area around the graphene layer, and a hole-rich area around the PE layer. Moreover, the Fermi level shifts towards the valence band maximum (VBM) of the PE layer, forming a p-type Schottky contact at the interface. Upon application of an electric field perpendicular to the PE/G interface, the Schottky contact can be transformed into an Ohmic contact via the tuning of the Schottky barrier height (SBH) of the PE/G interface. Compared with the A-type PE/G interfaces, the H-type requires a lower electric field to induce an Ohmic contact. All these results can provide deeper insights into the conduction mechanism of graphene-based polymer composites as field-shielding materials. Full article

(This article belongs to the Special Issue Graphene-Based Polymer Composites and Their Applications)

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14 pages, 3218 KiB

Open AccessArticle

Facile Fabrication of Superhydrophobic Graphene/Polystyrene Foams for Efficient and Continuous Separation of Immiscible and Emulsified Oil/Water Mixtures

by Chunxia Zhao, Haoran Huang, Jiaxin Li, Yuntao Li, Dong Xiang, Yuanpeng Wu, Ge Wang and Mingwang Qin

Polymers 2022, 14(11), 2289; https://doi.org/10.3390/polym14112289 - 5 Jun 2022

Cited by 5 | Viewed by 2254

Abstract

Three-dimensional superhydrophobic/superlipophilic porous materials have attracted widespread attention for use in the separation of oil/water mixtures. However, a simple strategy to prepare superhydrophobic porous materials capable of efficient and continuous separation of immiscible and emulsified oil/water mixtures has not yet been realized. Herein, [...] Read more.

Three-dimensional superhydrophobic/superlipophilic porous materials have attracted widespread attention for use in the separation of oil/water mixtures. However, a simple strategy to prepare superhydrophobic porous materials capable of efficient and continuous separation of immiscible and emulsified oil/water mixtures has not yet been realized. Herein, a superhydrophobic graphene/polystyrene composite material with a micro-nanopore structure was prepared by a single-step reaction through high internal phase emulsion polymerization. Graphene was introduced into the polystyrene-based porous materials to not only enhance the flexibility of the matrix, but also increase the overall hydrophobicity of the composite materials. The resulting as-prepared monoliths had excellent mechanical properties, were superhydrophobic/superoleophilic (water/oil contact angles were 151° and 0°, respectively), and could be used to continuously separate immiscible oil/water mixtures with a separation efficiency that exceeded 99.6%. Due to the size-dependent filtration and the tortuous and lengthy micro-nano permeation paths, our foams were also able to separate surfactant-stabilized water-in-oil microemulsions. This work demonstrates a facile strategy for preparing superhydrophobic foams for the efficient and continuous separation of immiscible and emulsified oil/water mixtures, and the resulting materials have highly promising application potentials in large-scale oily wastewater treatment. Full article

(This article belongs to the Special Issue Graphene-Based Polymer Composites and Their Applications)

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Review

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50 pages, 5461 KiB

Open AccessReview

Recent Advances in Graphene-Based Nanocomposites for Ammonia Detection

by Sara Maira M. Hizam, Adel Mohammed Al-Dhahebi and Mohamed Shuaib Mohamed Saheed

Polymers 2022, 14(23), 5125; https://doi.org/10.3390/polym14235125 - 24 Nov 2022

Cited by 16 | Viewed by 2852

Abstract

The increasing demand to mitigate the alarming effects of the emission of ammonia (NH₃) on human health and the environment has highlighted the growing attention to the design of reliable and effective sensing technologies using novel materials and unique nanocomposites with [...] Read more.

The increasing demand to mitigate the alarming effects of the emission of ammonia (NH₃) on human health and the environment has highlighted the growing attention to the design of reliable and effective sensing technologies using novel materials and unique nanocomposites with tunable functionalities. Among the state-of-the-art ammonia detection materials, graphene-based polymeric nanocomposites have gained significant attention. Despite the ever-increasing number of publications on graphene-based polymeric nanocomposites for ammonia detection, various understandings and information regarding the process, mechanisms, and new material components have not been fully explored. Therefore, this review summarises the recent progress of graphene-based polymeric nanocomposites for ammonia detection. A comprehensive discussion is provided on the various gas sensor designs, including chemiresistive, Quartz Crystal Microbalance (QCM), and Field-Effect Transistor (FET), as well as gas sensors utilising the graphene-based polymer nanocomposites, in addition to highlighting the pros and cons of graphene to enhance the performance of gas sensors. Moreover, the various techniques used to fabricate graphene-based nanocomposites and the numerous polymer electrolytes (e.g., conductive polymeric electrolytes), the ion transport models, and the fabrication and detection mechanisms of ammonia are critically addressed. Finally, a brief outlook on the significant progress, future opportunities, and challenges of graphene-based polymer nanocomposites for the application of ammonia detection are presented. Full article

(This article belongs to the Special Issue Graphene-Based Polymer Composites and Their Applications)

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