Special Issue "Graphene-Polymer Composites II"

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Applications".

Deadline for manuscript submissions: 31 December 2019.

Special Issue Editors

Dr. Artur Pinto
E-Mail Website
Guest Editor
Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
Interests: graphene-based materials; polymer composites; biomaterials; phototherapy; antibacterial materials; graphene inks
Prof. Fernão D. Magalhães
E-Mail Website
Guest Editor
LEPABE, Chemical Engineering Department, Faculty of Engineering, University of Porto, Portugal
Interests: synthetic and natural adhesives; lignocellulosic composites; high-performance industrial coatings; graphene-based biomaterials
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

The mechanical, electrical, thermal, magnetic, optical and biological properties of graphene have attracted a significant amount of attention from the research community since the isolation of single-atom-thick graphene layers by Geim and co-workers in 2004. Presenting a very high surface-to-volume ratio, relatively simple processability and low cost, graphene and graphene-based materials (GBMs) were soon identified as promising nanofillers for polymer matrices. Reports have shown notorious property enhancements for graphene-polymer composites (GPC) at very low filler loadings. Uses of GPC in varied fields, such as energy, electronics, catalysis, separation and purification, biomedicine, aerospace, tribology, etc., have been demonstrated and, in some cases, put into industrial practice. However, challenges still exist. Platelet agglomeration within the polymer matrix is often seen to hinder performance improvements. Poor interfacial adhesion between filler and matrix is also a limiting factor in many systems, demanding the tuning of the surface chemistry to promote physical or chemical interactions with the polymer chains. The range of routes for the fabrication of GBMs, leading to different morphologies, oxidation states, and degrees of platelet exfoliation, have an impact on the final properties of the composites that has not yet been fully addressed. Some argue that the potential of graphene, and its advantages in relation to other nanofillers, has not yet been fully demonstrated for polymer composites. On the other hand, recent findings suggest that some graphene forms are potentially biodegradable and biocompatible, which constitutes a major advantage, compared for example with carbon black or some forms of carbon-nanotubes, which have been demonstrated to be carcinogenic. Further studies are required, concerning not only the biological properties of GBMs, but also their potential applications in multiple fields.

This Special Issue invites original papers and reviews reporting on recent progress in the following areas:

  • Chemical and physical surface modifications of graphene and GBMs for improving dispersibility and compatibility with polymer matrices.
  • Fabrication methods of GPC in coating, film, bulk or particulate forms.
  • Properties of GPC (chemical, mechanical, thermal, electrical, magnetic, etc.).
  • Applications of GPC.
  • Biological properties of GBMs and GPC (biocompatibility, biointeractions, environmental toxicity, etc.).

It must be noted that the term “composite” should be understood here in its broader sense, describing a material, of any geometry and size, made of two or more constituent materials that do not lose their individual identities when combined.

Dr. Artur Pinto
Prof. Fernão D. Magalhães
Guest Editors

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Keywords

  • Graphene
  • Graphene oxide
  • Composites
  • Coatings
  • Adhesives
  • Fibers
  • Particles
  • Surface modification
  • Surface functionalization
  • Materials properties
  • Biological properties

Published Papers (9 papers)

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Research

Open AccessArticle
Nano-Level Damage Characterization of Graphene/Polymer Cohesive Interface under Tensile Separation
Polymers 2019, 11(9), 1435; https://doi.org/10.3390/polym11091435 - 02 Sep 2019
Abstract
The mechanical behavior of graphene/polymer interfaces in the graphene-reinforced epoxy nanocomposite is one of the factors that dictates the deformation and damage response of the nanocomposites. In this study, hybrid molecular dynamic (MD) and finite element (FE) simulations of a graphene/polymer nanocomposite are [...] Read more.
The mechanical behavior of graphene/polymer interfaces in the graphene-reinforced epoxy nanocomposite is one of the factors that dictates the deformation and damage response of the nanocomposites. In this study, hybrid molecular dynamic (MD) and finite element (FE) simulations of a graphene/polymer nanocomposite are developed to characterize the elastic-damage behavior of graphene/polymer interfaces under a tensile separation condition. The MD results show that the graphene/epoxy interface behaves in the form of elastic-softening exponential regressive law. The FE results verify the adequacy of the cohesive zone model in accurate prediction of the interface damage behavior. The graphene/epoxy cohesive interface is characterized by normal stiffness, tensile strength, and fracture energy of 5 × 10−8 (aPa·nm−1), 9.75 × 10−10 (nm), 2.1 × 10−10 (N·nm−1) respectively, that is followed by an exponential regressive law with the exponent, α = 7.74. It is shown that the commonly assumed bilinear softening law of the cohesive interface could lead up to 55% error in the predicted separation of the interface. Full article
(This article belongs to the Special Issue Graphene-Polymer Composites II)
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Open AccessArticle
Study on Graphene/CNC-Coated Bamboo Pulp Fabric Preparation of Fabrics with Thermal Conductivity
Polymers 2019, 11(8), 1265; https://doi.org/10.3390/polym11081265 - 31 Jul 2019
Abstract
Functional fabrics have gained attention as an environmentally-friendly synthesis route. In the current study, novelty bamboo pulp fabrics with thermal conductivity properties were prepared by coating the fabric with graphene and cellulose nanocrystal (G/CNC) solutions. The influences of G and CNC concentrations on [...] Read more.
Functional fabrics have gained attention as an environmentally-friendly synthesis route. In the current study, novelty bamboo pulp fabrics with thermal conductivity properties were prepared by coating the fabric with graphene and cellulose nanocrystal (G/CNC) solutions. The influences of G and CNC concentrations on properties of fabrics were studied. The viscosities of the G/CNC solutions increased with an increase of G contents. G had an obvious thickening effect. Furthermore, compounded fabrics with different G and CNC contents (GCBPFs) were prepared and extensively characterized in terms of thermal and mechanical properties, and morphology. The ultimate thermal conductivity, bursting strength, and tensile strength of the GCBPF were 0.136 W/m·K, 1.514 MPa, and 25.8 MPa, with 4 wt.% CNC and 3 wt.% G contents, respectively. The results demonstrated that the as-fabricated GCBPFs with favorable thermal conductivity could be applied as a novel fast cooling textile for the clothing industry. Full article
(This article belongs to the Special Issue Graphene-Polymer Composites II)
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Open AccessArticle
Effect of Conducting Polyaniline/Graphene Nanosheet Content on the Corrosion Behavior of Zinc-Rich Epoxy Primers in 3.5% NaCl Solution
Polymers 2019, 11(5), 850; https://doi.org/10.3390/polym11050850 - 10 May 2019
Cited by 2
Abstract
The corrosion behavior of zinc-rich epoxy primers or paints (ZRPs) with different conducting polyaniline-grafted graphene (PANI/Gr) contents was investigated. Conductivity of the formed PANI/Gr nanosheets was significantly improved by employing the Gr as the inner template to synthesize the PANI. The protective properties [...] Read more.
The corrosion behavior of zinc-rich epoxy primers or paints (ZRPs) with different conducting polyaniline-grafted graphene (PANI/Gr) contents was investigated. Conductivity of the formed PANI/Gr nanosheets was significantly improved by employing the Gr as the inner template to synthesize the PANI. The protective properties and electrochemical behavior of coatings with artificial defects were investigated by monitoring the free corrosion potential versus time and by using localized electrochemical impedance spectroscopy (LEIS). A synergetic enhancement of the physical barrier role of the coating and the zinc sacrificial cathodic protection was achieved in the case of ZRP including PANI/Gr nanosheets. In addition, the ZRP mixed with the PANI/Gr at a content of 0.6% exhibited the best anticorrosion performance across the range of investigated PANI/Gr contents. Full article
(This article belongs to the Special Issue Graphene-Polymer Composites II)
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Open AccessArticle
Graphene Oxide–Platinum Nanoparticle Nanocomposites: A Suitable Biocompatible Therapeutic Agent for Prostate Cancer
Polymers 2019, 11(4), 733; https://doi.org/10.3390/polym11040733 - 23 Apr 2019
Cited by 2
Abstract
Metal nanoparticles and the combination of metal nanoparticles with graphene oxide are widely used in environmental, agriculture, textile, and therapeutic applications. The effect of graphene oxide–green platinum nanoparticles (GO-PtNPs) on human prostate cancer cells (LNCaP) is unclear. Therefore, this study aimed to synthesize [...] Read more.
Metal nanoparticles and the combination of metal nanoparticles with graphene oxide are widely used in environmental, agriculture, textile, and therapeutic applications. The effect of graphene oxide–green platinum nanoparticles (GO-PtNPs) on human prostate cancer cells (LNCaP) is unclear. Therefore, this study aimed to synthesize a nanocomposite of GO-PtNPs and evaluate their effect on prostate cancer cells. Herein, we synthesized GO-PtNPs using vanillin and characterized GO-PtNPs. GO-PtNP cytotoxicity in LNCaP cells was demonstrated by measuring cell viability and proliferation. Both decreased in a dose-dependent manner compared to that by GO or PtNPs alone. GO-PtNP cytotoxicity was confirmed by increased lactate dehydrogenase release and membrane integrity loss. Oxidative stress induced by GO-PtNPs increased malondialdehyde, nitric oxide, and protein carbonyl contents. The effective reactive oxygen species generation impaired the cellular redox balance and eventually impaired mitochondria by decreasing the membrane potential and ATP level. The cytotoxicity to LNCaP cells was correlated with increased expression of proapoptotic genes (p53, p21, Bax, Bak, caspase 9, and caspase 3) and decreased levels of antiapoptotic genes (Bcl2 and Bcl-xl). Activation of the key regulators p53 and p21 inhibited the cyclin-dependent kinases Cdk2 and Cdk4, suggesting that p53 and p21 activation in GO-PtNP-treated cells caused genotoxic stress and apoptosis. The increased expression of genes involved in cell cycle arrest and DNA damage and repair, and increased levels of 8-oxo-deoxyguanosine and 8-oxoguanine suggested that GO-PtNPs potentially induce oxidative damage to DNA. Thus, GO-PtNPs are both cytotoxic and genotoxic. LNCaP cells appear to be more susceptible to GO-PtNPs than to GO or PtNPs. Therefore, GO-PtNPs have potential as an alternate and effective cancer therapeutic agent. Finally, this work shows that the combination of graphene oxide with platinum nanoparticles opens new perspectives in cancer therapy. However further detailed mechanistic studies are required to elucidate the molecular mechanism of GO-PtNPs induced cytotoxicity in prostate cancer. Full article
(This article belongs to the Special Issue Graphene-Polymer Composites II)
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Open AccessArticle
Anisotropic Cellulose Nanofibers/Polyvinyl Alcohol/Graphene Aerogels Fabricated by Directional Freeze-drying as Effective Oil Adsorbents
Polymers 2019, 11(4), 712; https://doi.org/10.3390/polym11040712 - 18 Apr 2019
Cited by 1
Abstract
Under the current situation of frequent oil spills, the development of green and recyclable high-efficiency oil-absorbing aerogel materials has attracted wide attention from researchers. In this study, we report a high-strength, three-dimensional hydrophobic cellulose nanofiber (CNF)/polyvinyl alcohol (PVA)/graphene oxide (GO) composite aerogel with [...] Read more.
Under the current situation of frequent oil spills, the development of green and recyclable high-efficiency oil-absorbing aerogel materials has attracted wide attention from researchers. In this study, we report a high-strength, three-dimensional hydrophobic cellulose nanofiber (CNF)/polyvinyl alcohol (PVA)/graphene oxide (GO) composite aerogel with an anisotropic porous structure, which was fabricated by directional freeze-drying technology using anisotropically grown ice crystals as a template, followed by hydrophobic treatment with a simple dip coating process. The prepared composite aerogel presented anisotropic multi-level pore microstructures, low density (17.95 mg/cm3) and high porosity (98.8%), good hydrophobicity (water contact angle of 142°) and great adsorption capacity (oil absorption reaching 96 times its own weight). More importantly, the oriented aerogel had high strength, whose compressive stress at 80% strain reached 0.22 MPa and could bear more than 22,123 times its own weight without deformation. Therefore, the CNF/PVA/GO composite aerogel prepared by a simple and easy-to-operate directional freeze-drying method is a promising absorbent for oil-water separation. Full article
(This article belongs to the Special Issue Graphene-Polymer Composites II)
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Open AccessArticle
Electrospun Graphene Nanosheet-Filled Poly(Trimethylene Terephthalate) Composite Fibers: Effects of the Graphene Nanosheet Content on Morphologies, Electrical Conductivity, Crystallization Behavior, and Mechanical Properties
Polymers 2019, 11(1), 164; https://doi.org/10.3390/polym11010164 - 17 Jan 2019
Cited by 1
Abstract
In this study the effects of increased graphene nanosheet (GNS) concentration on variations in the structure and properties of electrospun GNS-filled poly(trimethylene terephthalate) (PTT/GNS) composite fiber, such as its morphologies, crystallization behavior, mechanical properties, and electrical conductivity, were investigated. The effects of GNS [...] Read more.
In this study the effects of increased graphene nanosheet (GNS) concentration on variations in the structure and properties of electrospun GNS-filled poly(trimethylene terephthalate) (PTT/GNS) composite fiber, such as its morphologies, crystallization behavior, mechanical properties, and electrical conductivity, were investigated. The effects of GNS addition on solution rheology and conductivity were also investigated. GNSs were embedded in the fibers and formed protrusions. The PTT cold crystallization rate of PTT/GNS composite fibers increased with the gradual addition of GNSs. A PTT mesomorphic phase was formed during electrospinning, and GNSs could induce the PTT mesomorphic phase significantly during PTT/GNS composite fiber electrospinning. The PTT/GNS composite fiber mats (CFMs) became ductile with the addition of GNSs. The elastic recoveries of the PTT/GNS CFMs with 170 °C annealing were better than those of the as-spun PTT/GNS CFMs. Percolation scaling laws were applied to the magnitude of conductivity to reveal the percolation network of electrospun PTT/GNS CFMs. The electrical conductivity mechanism of the PTT/GNS CFMs differed from that of the PTT/GNS composite films. Results showed that the porous structure of the PTT CFMs influenced the performance of the mats in terms of electrical conductivity. Full article
(This article belongs to the Special Issue Graphene-Polymer Composites II)
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Open AccessArticle
Evaluation of Exfoliated Graphite to Graphene in Polyamide 66 Using Novel High Shear Elongational Flow
Polymers 2018, 10(12), 1399; https://doi.org/10.3390/polym10121399 - 17 Dec 2018
Abstract
Graphene has been publicized as the game changing material of this millennium. To this day, scalable production leading to exceptional material properties has been difficult to attain. Most methods require harsh chemicals, which result in destroying the graphene surface. A method was developed, [...] Read more.
Graphene has been publicized as the game changing material of this millennium. To this day, scalable production leading to exceptional material properties has been difficult to attain. Most methods require harsh chemicals, which result in destroying the graphene surface. A method was developed, exploiting high speed elongational flow in a novel designed batch mixer; creating a distribution of pristine few to many layer graphene flakes. The method focuses on exfoliating in a molten polyamide 66 (PA66) matrix, creating a graphene reinforced polymer matrix composite (G-PMC). The process revealed that high speed elongational flow was able to create few layer graphene. Graphite exfoliation was found driven in part by diffusion, leading to intercalation of PA66 in graphite. The intercalated structure lead to increases in the hydrogen bonding domain, creating anisotropic crystal domains. The thermal stability of the G-PMC was found to be dependent to the degree of exfoliation, PA66 crystal structure and composite morphology. The aim of this research is to characterize uniquely produced graphene containing polymer matrix composites using a newly created elongational flow field. Using elongational flow, graphite will be directly exfoliated into graphene within a molten polymer. Full article
(This article belongs to the Special Issue Graphene-Polymer Composites II)
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Open AccessArticle
High-Performance Biobased Unsaturated Polyester Nanocomposites with Very Low Loadings of Graphene
Polymers 2018, 10(11), 1288; https://doi.org/10.3390/polym10111288 - 20 Nov 2018
Cited by 1
Abstract
Graphene-reinforced tung oil (TO)-based unsaturated polyester nanocomposites were prepared via in situ melt polycondensation intergrated with Diels–Alder addition. Functionalized graphene sheets derived from graphene oxide (GO) were then extracted from the obtained nanocomposites and carefully characterized. Furthermore, dispersion state of the graphene nanosheets [...] Read more.
Graphene-reinforced tung oil (TO)-based unsaturated polyester nanocomposites were prepared via in situ melt polycondensation intergrated with Diels–Alder addition. Functionalized graphene sheets derived from graphene oxide (GO) were then extracted from the obtained nanocomposites and carefully characterized. Furthermore, dispersion state of the graphene nanosheets in the cured polymer composites and ultimate properties of the resultant biobased nanocomposites were investigated. Mechanical and thermal properties of the TO-based unsaturated polyester resin (UPR) were greatly improved by the incorporation of GO. For example, at the optimal GO content (only 0.10 wt %), the obtained biobased nanocomposite showed tensile strength and modulus of 43.2 MPa and 2.62 GPa, and Tg of 105.2 °C, which were 159%, 191%, and 49.4% higher than those of the unreinforced UPR/TO resin, respectively. Compared to neat UPR, the biobased UPR nanocomposite with 0.1 wt % of GO even demonstrated superior comprehensive properties (comparable stiffness and Tg, while better toughness and thermal stability). Therefore, the developed biobased UPR nanocomposites are very promising to be applied in structural plastics. Full article
(This article belongs to the Special Issue Graphene-Polymer Composites II)
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Open AccessArticle
Effect of Compatibilizer on the Interface Bonding of Graphene Oxide/Polypropylene Composite Fibers
Polymers 2018, 10(11), 1283; https://doi.org/10.3390/polym10111283 - 18 Nov 2018
Abstract
To improve the interfacial bonding and thermal stability of graphene oxide (GO)/polypropylene (PP) composite fibers, a composite fiber with PP as the matrix, GO as reinforcement and maleic anhydride-grafted PP (PP-g-MAH) as a compatibilizer was prepared by a simple and efficient melt-blending method. [...] Read more.
To improve the interfacial bonding and thermal stability of graphene oxide (GO)/polypropylene (PP) composite fibers, a composite fiber with PP as the matrix, GO as reinforcement and maleic anhydride-grafted PP (PP-g-MAH) as a compatibilizer was prepared by a simple and efficient melt-blending method. The GO content was 0.0–5.0 wt %. According to the Fourier Transform Infrared (FT-IR) spectroscopy results, the interfacial bonding in the PP/MAH/GO composite fibers was improved. The Dynamic Mechanical Analysis (DMA) results show that the addition of GO resulted in better interfacial adhesion and higher storage modulus (E′). The loss modulus (E″) of the PP/MAH/GO-x composite fibers increased with increasing amount of added GO, whereas the loss factor (tan δ) decreased. GO and PP-g-MAH were analyzed by Thermogravimetric Analysis (TGA). The thermal stability of the composite fibers was improved compared to PP. Differential Scanning Calorimetry (DSC) analysis showed that the addition of PP-g-MAH to the composite fiber improved the interfacial bonding of GO in the PP matrix. Thus, compatibility between the two components was obtained. Based on the Scanning Electron Microscopy (SEM) results, the PP fibers exhibited relative orientation due to the strong crystalline morphology. The rough section, PP/GO blend fiber exhibits a very clear phase separation morphology due to the incompatibility between the two and the compatibility of GO and PP in PP/MAH/GO-3 composite fiber is improved, resulting in the interface between the two has improved. Full article
(This article belongs to the Special Issue Graphene-Polymer Composites II)
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