Influence of graphene reinforcement in conductive polymer: Synthesis and characterization

Lightweight conductive polymers are considered for lightning strike mitigation in composites by synthesizing intrinsically conductive polymers (ICPs) and by the inclusion of conductive fillers in insulating matrices. Conductive films based on polyaniline (PANI) and graphene have been developed to improve through‐thickness conductivity of polymer composites. The result shows that the conductivity of PANI enhanced by blending polyvinylpyrrolidone (PVP) and PANI in 3:1 ratio. Conductive composite thin films are prepared by dispersing graphene in PANI. The conductivity of composite films was found to increase by 40× at 20 wt% of graphene inclusion compared with PVP and PANI blend. Fourier‐transform‐infrared (FTIR) spectra confirmed in situ polymerization of the polymer blend. The inclusion of graphene also exhibits an increase in Tg by 21°C. Graphene additions also showed an increase in thermal stability by approximately 148°C in the composite films. The mechanical result obtained from DMA shows that inclusion of graphene increases the tensile strength by 48% at 20 wt% of graphene reinforcement. A thin, highly conductive surface that is compatible with a composite resin system can enhance the surface conductivity of composites, improving its lightning strike mitigation capabilities.     

Synthesis and characterization of organosoluble,thermoplastic elastomer/clay nanocomposites

We synthesized organosoluble, thermoplastic elastomer/clay nanocomposites by making a jelly like solution of ethylene vinyl acetate containing 28% vinyl acetate (EVA‐28) and blending it with organomodified montmorillonite. Sodium montmorillonite (Na⁺‐MMT) was made organophilic by the intercalation of dodecyl ammonium ions. X‐ray diffraction patterns of Na⁺‐MMT and its corresponding organomodified dodecyl ammonium ion intercalated montmorillonite (12Me‐MMT) showed an increase in the interlayer spacing from 11.94 to 15.78 Å. However, X‐ray diffraction patterns of the thermoplastic elastomer and its hybrids with organomodified clay contents up to 6 wt % exhibited the disappearance of basal reflection peaks within an angle range of 3–10°, supporting the formation of a delaminated configuration. A hybrid containing 8 wt % 12Me‐MMT revealed a small hump within an angle range of 5–6° because of the aggregation of silicate layers in the EVA‐28 matrix. A transmission electron microscopy image of the same hybrid showed 3–5‐nm 12Me‐MMT particles dispersed in the thermoplastic elastomer matrix; that is, it led to the formation of nanocomposites or molecular‐level composites with a delaminated configuration. The formation of nanocomposites was reflected through the unexpected improvement of thermal and mechanical properties; for example, the tensile strength of a nanocomposite containing only 4 wt % organophilic clay was doubled in comparison with that of pure EVA‐28, and the thermal stability of the same nanocomposite was higher by about 34 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2065–2072, 2002     

Synthesis and characterization of chitosan-based polyurethane elastomer dispersions

Abstract  

A number of aqueous polyurethane dispersions were synthesized by the reaction of poly(ε-caprolactone) and isophorone diisocyanate, extended with different mass ratios of chitosan and dimethylol propionic acid. Their chemical structures were characterized by using FTIR, ¹H NMR, and ¹³C NMR spectroscopy, and thermal properties were determined by TGA. Incorporation of chitosan into the polyurethane backbone improved thermal stability. The hydrophilicity of the prepared polymers was also examined by contact angle measurements. For all samples, the contact angles increased by increasing the amount of chitosan. The increased contact angle is ascribed to the decrease of the hydrophilicity of the polyurethanes, which is reduced by the increasing amount of chitosan with respect to dimethylol propionic acid chain extender.     

Synthesis and characterization of a novel biodegradable,thermoplastic polyurethane elastomer

A series of biodegradable, thermoplastic polyurethane elastomers poly(?‐caprolactone‐co‐lactide(polyurethane [PCLA–PU] were synthesized from a random copolymer of L ‐lactide (LA) and ?‐caprolactone (CL), hexamethylene diisocyanate, and 1,4‐butanediol. The effects of the LA/CL monomer ratio and hard‐segment content on the thermal and mechanical properties of PCLA–PUs were investigated. Gel permeation chromatography, IR, ¹³C NMR, and X‐ray diffraction were used to confirm the formation and structure of PCLA–PUs. Through differential scanning calorimetry, tensile testing, and tensile‐recovery testing, their thermal and mechanical properties were characterized. Their glass‐transition temperatures were below ?8 °C, and their soft domains became amorphous as the LA content increased. They displayed excellent mechanical properties, such as a tensile strength as high as 38 MPa, a tensile modulus as low as 10 MPa, and an elongation at break of 1300%. Therefore, they could find applications in biomedical fields, such as soft‐tissue engineering and artificial skin. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5505–5512, 2006     

Synthesis and characterization of conductive polyaniline/TiO2 composite nanofibers

Fibrillar conductive polyaniline/TiO₂ (PANI/TiO₂) nanocomposites with different TiO₂ amount were synthesized with a template-free in situ polymerization method and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and conductivity measurement. The morphology determination shows that the PANI/TiO₂ composite nanofibers are relatively uniform with the diameter and length in the range of 20–40 nm and 390–420 nm respectively. It also shows that the TiO₂ of the composite is rutile crystalline and PANI has some degree of crystallinity. The IR measurement indicates that there is a strong interaction between the PANI and TiO₂ nanoparticles, and it has a beneficial effect on the thermal stability of the composite nanofiber. The conductivity of PANI/TiO₂ composites changes with TiO₂ amount and reaches an optimum value of 2.86 S/cm at 11.1 wt% TiO₂. Translated from Journal of Northwest Normal University (Natural Science), 2006, 42(4): 67–70 (in Chinese)     

Synthesis and characterization of polyaniline/silicon dioxide composites and preparation of conductive films

The focus of this study was to synthesize the inherently conductive polymer polyaniline using an optimized process to prepare polyaniline/silicon dioxide (PANI/SiO₂) composites by in situ polymerization and ex situ solution mixing. PANI and PANI/SiO₂ composite films were prepared by drop‐by‐drop and spin coating methods. The electrical conductivities of HCl doped PANI film and PANI/SiO₂ composite films were measured according to the standard four‐point‐probe technique. The composite films exhibited an increase in electrical conductivity over neat PANI. PANI and PANI/SiO₂ composites were also investigated by spectroscopic methods including UV‐Vis, FT‐IR, and Photoluminescence. UV‐Vis and FT‐IR studies showed that SiO₂ particles affect the quinoid units along the polymer backbone and indicate strong interactions between the SiO₂ particles and the quinoidal sites of PANI (doping effect). The photoluminescence properties of PANI and PANI/SiO₂ composites were studied and the PANI/SiO₂ composites showed increased intensity as compared to neat PANI. The increase of conductivity of PANI/SiO₂ composite may be partially due to the doping or impurity effect of SiO₂ where the silicon dioxides compete with chloride ions. The morphology of particles and films were examined by a scanning electron microscope (SEM). SEM measurements indicated that the SiO₂ were well dispersed and isolated in composite films. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis and characterization of in-chain silyl-hydride functional SBR and self-crosslinking elastomer

Functional in-chain silyl-hydride(Si-H) SBR copolymers of 4-vinyiphenyldimethylsilanol(VPDMS) and butadiene were synthesized by living anionic polymerization,in which active group Si-H was not lost and its content was controllable. Corresponding self-crosslinking elastomers were obtained by hydrosilation of Si-H group with vinyl bonds in chain.The copolymers and elastomers were characterized by ~1H NMR,size exclusion chromatography(SEC),Fourier transform infrared (FTIR) spectroscopy,differential scanning calorimetry(DSC),and thermogravimetry analysis(TGA) techniques.     

High performance lithium-sulfur batteries by facilely coating a conductive carbon nanotube or graphene layer

A dual-layer cathode electrode is constituted by facilely coating a conductive carbon nanotube or graphene layer on the pristine sulfur cathode electrode. The conductive layer can effectively improve the conductivity and suppress the polysulfide diffusion, giving rise to an enhanced electrochemical performance for Li-S batteries.     

Synthesis, characterization and in vitro degradation study of a novel and rapidly degradable elastomer

Biodegradable elastomers represent a useful class of biomaterials. In this paper, a novel biodegradable elastomer, poly(PEG-co-CA) (PEC), was synthesized by condensation of poly(ethylene glycol) (PEG) and citric acid (CA) under atmospheric pressure without any catalyst. We first synthesized a pre-polymer by carrying out a controlled condensation reaction between PEG and citric acid, and then post-polymerised and simultaneously cross-linked the pre-polymer in the mould at 120 °C. The pre-polymer was characterized by FT-IR, ¹H NMR, ¹³C NMR, GPC and DSC. A series of polymers were prepared at different post-polymerisation time and different monomer ratios. Measurements on the mechanical properties of PEC testified that the new polymers are elastomers with low hardness and big elongation, and hydrolytic degradation of the polymer films in a buffer of pH 7.4 at 37 °C showed that PEC had excellent degradability (all the films show the weight losses more than 60% after 96 h incubation). The different post-polymerisation time and monomer ratio had strong influence on the degradation rates and mechanical performances. The material is expected to be useful for controlled drug delivery and other biomedical applications.     

Electrically conductive composites of collagen and graphene

Russian Chemical Bulletin - New composite materials of collagen with electrical conductivity up to 6.1?10–4 S cm–1 were obtained using colloidal dispersions of...     

Synthesis and electrical,rheological and thermal characterization of conductive polyurethane

This work studies the electrical, rheological, and thermal characteristics for polyurethane (PU) capped with tetraaniline as a new material, tetraaniline-containing poly(urethane–urea) (TAPU). The conductivities can be increased from less than 10⁻¹⁰ S/cm for pure PU to 10⁻⁴ S/cm for TAPU, independently of the length of the soft segment in the TAPU backbone chain. The tensile strength and modulus are increased when PU is copolymerized with tetraaniline. The viscoelastic creep can be effectively simulated using a Burgers model. Additionally, TAPU has higher viscosity, higher retardation time, and lower compliance J ₁ than regular PU. Restated, TAPU exhibits less elastic but superior permanent deformation than PU because tetraaniline functions as a chain holder. The thermogravimetric analytic (TGA) results reveal that TAPU has lower T _d, smaller T _mw1 and T _mw2, and higher char yield because the dehydration of the urea-containing polymer produces a thin layer from a nitrogen compound on the polymer’s surface, which insulates the underlying polymer from heat and oxygen.     

Preparation and characterization of polyaniline/MMT conductive composites

Polyaniline/montmorillonite (PAn/MMT) composite material has been prepared through chemical‐oxidative polymerization by using NH₄S₂O₈ as the oxidant, and it was found that both the composites have inorganic and organic material characteristics and many outstanding performance through the copolymerization coupling of MMT and polyaniline. Infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and transmission electron microscopy (TEM) are used to characterize the composition and structures of composite materials, as well as test the conductivity of composite materials through a four‐probe technique. The preparation conditions of PAn/MMT conducting composites are optimized. The optimal conditions have been identified for the reaction time, amount of oxidizer, concentration of HCl, and the amount of MMT. Besides, the results show that when the reaction lasts for 8 hr in the ice bath, the amount of MMT is 0.4 g/5 ml An, the mole ratio of oxidant to aniline is 1, and the concentration of hydrochloric acid is 2 M, the composite had the largest conductivity up to 11.5 S/cm. In addition, we also did an elemental analysis of the composite mechanism of PAn/MMT composites. Copyright © 2008 John Wiley & Sons, Ltd.     

PMMA／石墨导电复合材料的制备与表征

以可膨化石墨为原料,高温处理得到膨化石墨,再经过超声处理,得到纳米薄片石墨。将得到的纳米薄片石墨与甲基丙烯酸甲酯单体在超声作用下预聚,灌模,得到块状的聚甲基丙烯酸甲酯(PMMA)/石墨复合材料。用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、选区电子衍射SAD、红外、热重等分析仪器表征了纳米石墨薄片及PMMA/石墨复合材料。测试了复合材料的力学、电学性能,发现在室温下该复合材料的渗滤阀值为1.3%(wt),且保证石墨含量在1.4%(wt)时,即可保证复合材料具有良好的电学和力学性能。     

Straightforward synthesis of conductive graphene/polymer nanocomposites from graphite oxide

The reduction of graphite oxide (GO) in the presence of reactive poly(methyl methacrylate) (PMMA), under mild biphasic conditions, directly affords graphene grafted with PMMA. The resulting nanocomposite shows excellent electrical conductivities resulting from the optimal dispersion and exfoliation of graphene in the polymer matrix.     

Synthesis and characterization nanocomposite of the graphene oxide/polyacrylic acid modified with 2-mercaptoethanol

In this research, synthesis and characterization of the nano-graphene oxide (GO) based on the modified polyacrylic acid (PAA) have been carried out. Formation of esteric bonds between the carboxyl functional groups of the GO surface and the hydroxyl groups of PAA was confirmed by FTIR spectroscopy. The result of this synthesis is covalent modification of graphene oxide during the polymerization process and this modification has caused improvement and change in some properties of graphene oxide including solubility of nanocomposite. Additionally, structure and stability of composite were studied by SEM, XRD and TGA.     

Morphological and structural characterization of polypropylene/conductive graphite nanocomposites

The structure and morphology of polypropylene/conductive graphite (PP/CG) composites were studied by wide angle X-ray diffraction, small-angle X-ray scattering and scanning electron microscopy. An effect of graphite on the crystallization behavior was observed and the opposite influences of enhanced thermal conductivity and hinder of chain mobility on the formation of the γ-phase of PP were discussed.     

Synthesis and characterization of undecatungstotitanates incorporating a lanthanide or a transition metal

Summary K_n[TiW₁₁M(H₂O)O₃₉]·xH₂)(M=F, Co, Cr, Cu, Mn or Zn) and K₁₃[Ln(TiW₁₁O₃₉)₂]·xH₂O (Ln=a lanthanide) complexes have been prepared and characterized by elemental analysis, by u.v.-vis. and i.r. spectroscopy, by magnetic susceptibility measurements and by thermal measurements.     

Transparent and conductive thin films of graphene/polyaniline nanocomposites prepared through interfacial polymerization

This communication reports a simple, one-pot procedure for the synthesis and processing of transparent and conductive thin films of graphene/polyaniline nanocomposites based on an interfacial polymerization. Thin films presenting transmittance of 89% and sheet resistance of 60.6 ? sq(-1) are spontaneously obtained and can be easily transferred to suitable substrates.     

Synthesis and characterization of a novel binuclear iron phthalocyanine/reduced graphene oxide nanocomposite for non-precious electrocatalyst for oxygen reduction

Binuclear iron phthalocyanine/reduced graphene oxide(bi-Fe Pc/RGO) nanocomposite with good electrocatalytic activity for ORR in alkaline medium was prepared in one step. High angle annular dark field image scanning transmission electron microscopy(HAADF-STEM) and energy dispersive X-ray spectroscopy element mapping results show bi-Fe Pc was uniformly distributed on RGO. An obvious cathodic peak located at about-0.23 V(vs. SCE) in CV and an onset potential of-0.004 V(vs. SCE) in LSV indicate the as-prepared bi-Fe Pc/RGO nanocomposite possesses high activity which is closed to Pt/C for ORR. The ORR on bi-Fe Pc/RGO nanocomposite follows four-electron transfer pathway in alkaline medium. Compared with Pt/C, there is only a slight decrease(about 0.02 V vs. SCE) for bi-Fe Pc/RGO nanocomposite when the methanol exists. The excellent activity and methanol tolerance in alkaline solutions proves that bi-Fe Pc/RGO nanocomposite could be considered as a promising cathode catalyst for alkaline fuel cells.