Facile in-situ preparation of polyaniline/graphene nanocomposites using methanesulfonic acid

Polyaniline (PANI)/graphene composites were prepared by the in-situ polymerization of aniline in a 1 M aqueous solution of methanesulfonic acid (MSA) containing graphene, which was prepared separately from graphite powders by simple sonication in MSA. Graphite powders spontaneously exfoliated to form graphene (GPM), which was then quenched with excess water, filtered, and dried to produce powders. The dried graphene powders produced were re-dispersed well in a 1 M MSA aqueous solution, in which the in-situ polymerization of aniline was performed. The resulting PANI/GPM composite had a conducting emeraldine salt (ES) form, and showed good electrical and thermal properties, compared to pure PANI prepared using a 1 M HCl solution. The PANI/GPM composite could be dissolved in a MSA solution and spin-coated in a conducting ES form of PANI. In contrast, the ES form produced from a HCl solution was insoluble in organic solvents and needed to be reduced to convert it to the emeraldine base form to produce a PANI solution. Therefore, the in-situ preparation of PANI/graphene composites using MSA provides a facile means of improving the thermal and electrical properties of PANI and its processability.     

Intercalated polyaniline/Na-montmorillonite nanocomposites via oxidative polymerization

This work focuses on the preparation, characterization and electrical conductive properties of intercalated polyaniline/Na-montmorillonite nanocomposites. These materials consisting of polyaniline and Na-montmorillonite were prepared by oxidative polymerization with benzoyl peroxide as oxidizing agent. The synthesized nanocomposites were investigated by a series of characterization techniques; including Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and thermal analysis. X-ray diffraction and scanning electron microscopy images showed that the polyaniline was inserted into the clay layers. The modest increase in layer spacing was as much as 0.53 nm. The thermogravimetric analysis and differential thermal analysis demonstrated the improved thermal stability of the intercalated nanocomposites relative to the pure polyaniline due to the incorporated Na-montmorillonite. The room temperature electrical conductivity of nanocomposites varied from 1.0 × 10⁻⁷ to 5.8 × 10⁻⁵ Scm⁻¹.     

Facile synthesis of reduced graphene oxide/CeO2 nanocomposites and their application in supercapacitors

The combination of the attractive properties of graphene with excellent characteristics of other functional nanomaterials has become a popular pathway for achieving applications in multiple fields. Herein, reduced graphene oxide (RGO)/CeO₂ nanocomposites with enhanced capacitive performance were designed and synthesized by a facile two-step approach with a self-assembly method followed by thermal treatment. The structure, morphology and composition of the resulting RGO/CeO₂ nanocomposites were systematically investigated. The presence of RGO can prevent the aggregation and control the structures of the CeO₂ nanocrystals in the annealing process. The nanocomposites as electrode materials for supercapacitor exhibited an enhanced capacitive performance due to the synergic effect between RGO nanosheets and CeO₂ nanocrystals. The excellent capacitive performance of the RGO/CeO₂ nanocomposites offer great promise for supercapacitor applications.     

Synthesis and characterization of CTAB‐intercalated graphene/polyaniline nanocomposites via in situ oxidative polymerization

Polyaniline/graphene (PANI/GN) nanocomposites were fabricated via in‐situ oxidative polymerization of aniline in the presence of cetyltrimethylammonium bromide (CTAB) modified graphene (CGN) in 1M hydrochloric acid (HCl) solution. The morphology and structure of PANI/GN samples were investigated by Fourier transform infrared spectrum, X‐ray diffraction, ultraviolet and visible spectrum, thermogravimetric analysis, field‐emission scanning microscope (FE‐SEM), and transmitting electron microscopy (TEM). The conductivities of the PANI/GN nanocomposites were measured using four‐probe electrical conductivity measurement. The results indicated that the GN sheets disperse into the form of monolayer or stack few layers in PANI matrix. The GN sheets serve as a support material for PANI particles and the structure of GN covered with PANI nanoparticles were confirmed by FE‐SEM and TEM. The electrical conductivities of the PANI/GN samples have been improved compared with pure PANI prepared in the similar condition. POLYM. COMPOS., 36:1767–1774, 2015. © 2014 Society of Plastics Engineers     

Facile synthesis of graphene/polyaniline composite hydrogel for high-performance supercapacitor

The graphene/polyaniline (PANI) composite hydrogel was successfully prepared by a one-step hydrothermal method. The morphology and structure of the sample were characterized by digital camera, scanning electron microscopy, and Fourier transform infrared spectroscopy spectra. By combining the advantages of high conductivity of graphene and high pseudocapacitance of PANI, the composite hydrogel was taken as supercapacitor electrode material. Cyclic voltammetry and galvanostatic charge/discharge experimental results show that the composite has excellent electrochemical performance. The specific capacitance value is 258.5 F g^?1 at a scan rate of 2 mV s^?1 and the specific capacitance value is up to 307 F g^?1 at a current density of 0.2 A g^?1. The specific capacitance value can still maintain 90 % of the initial value after repeating the galvanostatic charge–discharge for 1000 cycles at a current density of 1.0 A g^?1 showing good cycle stability.     

原位插层聚合制备PVC/蒙脱土纳米复合材料

采用氯乙烯单体直接插层到蒙脱土中进行原位插层聚合，制备纳米复合材料，并用小角X射线衍射（XRD）、扫描电子显微镜（SEM）和电子探针技术对复合材料进行了结构表征。实验结果表明：采用原位插层聚合法制得的PVC／蒙脱土（MMT）复合材料为剥离型纳米复合材料。     

Facile hydrothermal synthesis and optical limiting properties of TiO2-reduced graphene oxide nanocomposites

TiO₂/reduced graphene oxide (RGO) nanocomposites Gx (RGO titania nanocomposite, x grams tetrabutyl titanate per 0.03 g RGO, x = 0.25, 0.50, 1.00) were prepared by a hydrothermal method: graphene oxide was reduced to RGO in a 2:1 water:ethanol mixture in the presence of varying quantities of tetrabutyl titanate, which deposited as TiO₂ on the RGO sheets. The nanocomposites were characterized by a combination of Fourier transform infrared spectroscopy, diffuse reflectance ultraviolet–visible spectroscopy, photoluminescence spectroscopy, Raman spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy studies. The nanocomposite G0.25 exhibits enhanced nonlinear optical properties compared to its individual components, which is ascribed to a combination of mechanisms. The role of defects and electron/energy transfer in the optical limiting performance of G0.25 was clarified with the help of Raman and photoluminescence spectroscopies. Intensity-dependent switching between reverse saturable absorption and saturable absorption behavior was observed with the G0.50 nanocomposite.     

Facile synthesis and thermal properties of waterglass-based silica xerogel nanocomposites containing reduced graphene oxide

In this study, new rGO-silica xerogel nanocomposites (SX-rGO) and its glass fiber reinforced composites (GFR-SX-rGO) were prepared, and its microstructure and thermal properties were evaluated. The raw material was a mixed dispersion prepared by adding 0.01–2.5?wt% of reduced graphene oxide (rGO) to waterglass (6% SiO₂). A hydrogel was prepared via sol-gel reaction of this raw material, which was then immersed in hydrochloric acid, hydrophobized in a siloxane/2-propanol reaction system, and then dried at ambient pressure to obtain a hydrophobic carbon-silica xerogel composite. The obtained samples were characterized by N₂ physisorption (at 77?K), solid ²⁹Si Magic angle spinning nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, differential scanning calorimetry, thermogravimetric analysis, hydrophobicity, and thermal conductivity. It was found that as the amount of rGO was increased, the specific surface area of the nanocomposite decreased by ~25% from 535 to 403?cm²/g, and the average pore size and pore volume were almost halved. The thermal decomposition temperature of the SX-rGO was increased markedly by the addition of rGO. Moreover, the GFR-SX-rGO-0.5 showed low density (0.208?g/cm³), high contact angle (146°) and low thermal conductivity (0.0199?W/mK).     

原位聚合法制备GO/PAN复合膜及其性能的研究（英文）

通过原位聚合法制备了氧化石墨烯/聚丙烯腈(GO/PAN)聚合物,采用水相成膜法制得GO/PAN复合膜,探讨了聚合过程中GO用量对PAN的单体转化率(Y)和增比黏度(ηsp)的影响,研究了GO/PAN复合膜的结构和性能。结果表明:GO的加入使PAN的ηsp和Y都有所提高;当加入GO质量分数为2%时,相对于PAN,其Y提高了13.4%,ηsp提高了77.3%;GO片层均匀地分布在GO/PAN复合膜基体当中,并且GO与PAN之间存在一定的作用力;与纯PAN相比,GO/PAN复合膜的结晶度、热稳定性和力学性能都得到一定程度提高,当GO质量分数为2%时,所制得的GO/PAN复合膜的结晶度为47.9%,最大分解温度304℃,600℃时质量保持率为49.8%,强度为6.0 MPa。     

原位聚合法制备聚苯胺/改性羰基铁粉复合材料

采用正硅酸乙酯(TEOS)对羰基铁粉(CIP)表面改性,通过原位聚合法制备了聚苯胺(PANI)/改性CIP复合材料。傅里叶变换红外光谱验证了SiO2和CIP表面形成了化学键。耐酸性实验表明:TEOS可在较长时间内保护CIP不被酸腐蚀,保证了制备PANI/CIP复合材料过程中CIP处于SiO2的有效保护下。所得复合材料为CIP表面包覆直径约20 nm均匀致密的PANI微粒,复合效果明显改善。复合材料电导率与CIP未改性前处于相同数量级。     

Heteroatom-doped reduced graphene oxide/polyaniline nanocomposites with improved n-type thermoelectric performance

Polyaniline (PANI) is a potential candidate for n-type thermoelectric (TE) materials owing to its intrinsic electrical conductivity, low thermal conductivity, and facile synthesis techniques. However, its low Seebeck coefficient and power factor have limited its widespread usage. In this study, nitrogen-doped, and sulfur-nitrogen co-doped reduced graphene oxide (rGO) were used for tuning the TE properties of PANI. Doped rGO and PANI/doped-rGO nanocomposites were prepared via hydrothermal technique and chemical oxidative polymerization respectively and thereafter characterized. The TE properties of the nanocomposites were also studied and an optimized Seebeck coefficient, power factor and zT value of −1.75 mV K⁻¹, 95 μW m⁻¹ K⁻² and 0.06, respectively were reported for the PANI nanocomposite containing 1 wt% sulfur-nitrogen co-doped rGO. These results suggest that PANI/heteroatom-doped rGO can serve as promising candidates for n-type based TE applications.     

Facile synthesis of sandwich-like polyaniline/boron-doped graphene nano hybrid for supercapacitors

The physicochemical property of chemically prepared graphene can be significantly changed due to the incorporating of heteroatoms into graphene. In this article, boron-doped graphene sheets are used as carbon substrates instead of graphene for loading polyaniline by in situ polymerization. Compared with the individual component and polyaniline/non-doped graphene, the sandwich-like polyaniline/boron-doped graphene exhibits remarkably enhanced electrochemical specific capacitance in both acid and alkaline electrolytes. In a three-electrode configuration, the hybrid has a specific capacitance about 406 F g⁻¹ in 1 M H₂SO₄ and 318 F g⁻¹ in 6 M KOH at 1 mV s⁻¹. In the two-electrode system of a symmetric supercapacitor, this hybrid achieves a specific capacitance about 241 and 189 F g⁻¹ at 0.5 A g⁻¹ with a specific energy density around 19.9 and 30.1 Wh kg⁻¹, in the acid and alkaline electrolytes, respectively. The as-obtained polyaniline/boron-doped graphene hybrid shows good rate performance. Notably, the obtained electrode materials exhibit long cycle stability in both acid and alkaline electrolytes (∼100% and 83% after 5000 cycles, respectively). The improved electrochemical performance of the hybrid is mainly attributed to the introduction of additional p-type carriers in carbon systems by boron-doping and the well combination of pseudocapacitive conducting polyaniline.     

Pressure-assisted synthesis and morphology control of polyaniline

Nanostructured PANI has been successfully prepared via pressure-assisted synthesis by using a U-type device consist of two liquid cells linked by nanopore arrays. Our results indicate that changing the pressure difference (ΔP) between two liquid cells will not influence the crystal structure and composition obviously but adjust their morphology. The sample obtained under bigger ΔP possesses a rod-like nanostructure with smaller size and narrower size distribution, while the sample obtained under smaller ΔP possesses a coral-like nanostructure with bigger size and wider size distribution. In addition, the sample obtained under higher ΔP possesses better thermal stability.     

Multifunctional polyimide/graphene oxide composites via in situ polymerization

In this article, we detail an effective way to improve electrical, thermal, and gas barrier properties using a simple processing method for polymer composites. Graphene oxide (GO) prepared with graphite using a modified Hummers method was used as a nanofiller for r‐GO/PI composites by in situ polymerization. PI composites with different loadings of GO were prepared by the thermal imidization of polyamic acid (PAA)/GO. This method greatly improved the electrical properties of the r‐GO/PI composites compared with pure PI due to the electrical percolation networks of reduced graphene oxide within the films. The conductivity of r‐GO/PI composites (30:70 w/w) equaled 1.1 × 10¹ S m^?1, roughly 10¹⁴ times that of pure PI and the oxygen transmission rate (OTR, 30:70 w/w) was reduced by about 93%. The Young's modulus of the r‐GO/PI composite film containing 30 wt % GO increased to 4.2 GPa, which was an approximate improvement of 282% compared with pure PI film. The corresponding strength and the elongation at break decreased to 70.0 MPa and 2.2%, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40177.     

Synthesis of polypyrrole/indium tin oxide nanocomposites via miniemulsion polymerization

Polypyrrole/indium tin oxide nanocomposites were synthesized via in situ miniemulsion polymerization of pyrrole monomer in the presence of indium tin oxide nanoparticles. Different nanocomposites were synthesized by different loadings of nano indium tin oxide. The morphology and nanoparticles distribution of the nanocomposites were characterized by electron microscopy. The results of XRD and TEM analysis showed that indium tin oxide nanoparticles were well placed in the polymeric structure of latex. FTIR analysis was used for the characterization of synthesized polypyrrole and its nanocomposites. TGA analysis was performed to investigate the thermal behavior of pristine polypyrrole and its nanocomposites. Conductivities of nanocomposites were measured by 4-point probe method and compared to the neat polymer.     

Facile solid-state synthesis of Ag/graphene oxide nanocomposites as highly active and stable catalyst for the reduction of 4-nitrophenol

A facile solid-state synthetic route was used to fabricate graphene oxide (GO) decorated with Ag nanoparticles. Ag/GO nanocomposites were prepared by reducing silver acetate with ascorbic acid in the presence of GO at ambient conditions. The characterization results showed that Ag nanoparticles with an average diameter of ~ 50 nm were well dispersed on the surface of GO nanosheets. Moreover, an application of the obtained Ag/GO nanocomposites as a catalyst in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol by NaBH₄ was demonstrated. The Ag/GO nanocomposites exhibited high activity and stability for the catalytic reduction of 4-NP.     

In situ polymerization of bio‐based thermosetting polyurethane/graphene oxide nanocomposites

Novel bio‐based polyurethane/graphene oxide (GO) nanocomposites have been successfully synthesized from biorenewable epoxidized soybean‐castor oil fatty acid‐based polyols with considerable improvement in mechanical and thermal properties. The GO was synthesized via a modified pressurized oxidation method, and was investigated using Raman spectra, AFM and XPS, respectively. The toughening mechanism of GO in the bio‐based polyurethane matrix was explored. The elongation at break and toughness of polyurethane were increased by 1.3 and 0.8 times with incorporation of 0.4 wt % GO, respectively. However, insignificant changes in both mechanical strength and modulus were observed by adding GO. The results from thermal analysis indicated that the GO acts as new secondary soft segments in the polyurethane which lead to a considerable decrease in the glass transition temperature and crosslink density. The SEM morphology of the fracture surface after tensile testing showed a considerable aggregation of graphene oxide at concentrations above 0.4 wt %. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41751.     

Gas phase mineralized graphene as core/shell nanosheet supports for single-site olefin polymerization catalysts and in-situ formation of graphene/polyolefin nanocomposites

A versatile gas phase mineralization process affords nanosheets containing a functionalized graphene (FG) core and a thin silica shell. The number of cycles, exposing FG to sequenced tetrachlorosilane and water vapors, controls the silica content and the silica shell thickness. The resulting high surface area core/shell nanosheets, containing 22 to 34 wt.-% silica, are used to immobilize single-site catalysts. During polymerization, the FG/silica nanosheets are uniformly dispersed in ultrahigh molecular weight polyethylene. This catalytic polymerization filling process, exploiting the encapsulation of graphene in a silica shell, is of interest to prepare electrically insulating carbon/polyolefin composite materials with high thermal conductivity useful in lightweight engineering.     

Facile dispersion of exfoliated graphene/PLA nanocomposites via in situ polycondensation with a melt extrusion process and its rheological studies

This work attempted to improve the dispersion of graphene by coating poly(lactic acid) pellets with a masterbatch before melt processing. An in situ polycondensation reaction of lactic acid oligomer was utilized to prepare the masterbatch (MB) of exfoliated graphene (GR). MB dispersed composites of poly(lactic acid) (PLA) were fabricated by melt extrusion of MB‐coated PLA. One normal coated composite without MB coating (PLA‐M‐0.2GR) was fabricated for comparing properties. X‐ray diffraction, Raman spectroscopy, and morphological studies revealed better compatibility, dispersion, and interaction of GR for the diluted‐MB composite compared to the normal coated composite. The thermal stability, crystallization properties, and mechanical properties of the composites were examined, and the effect of short PLA chains in diluted‐MB composites was observed. The melt rheology nature of the composites was examined. Cole–Cole plots and Han plots suggested a uniform distribution of graphene. The sample PLA‐MB‐0.05GR showed improved modulus and elongation at break. It also showed better dispersion of GR, comparable thermal stability, good miscibility, good chain mobility, and high activation energy. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46476.     

Facile synthesis of SBA-15/polyaniline nanocomposites with high electrochemical activity under neutral and acidic conditions

A facile synthesis of SBA-15/polyaniline (PANI) nanocomposites was developed via chemical polymerization in a pH 3 solution based on the electrostatic adsorption of positively charged anilinium ions on negatively charged SBA-15. X-ray diffraction, N₂ sorption isotherms, transmission electron microscopy and scanning electron microscopy characteristics indicated that PANI chains were distributed both on the inside and outside surfaces of the SBA-15 pores. A possible synthetic scheme for the creation of nanocomposites has been proposed. The SBA-15/PANI nanocomposites showed high, stable electrochemical activity in neutral and acidic conditions. The preliminary use of the SBA-15/PANI nanocomposites as an electroactive support for the selective detection of uric acid (UA) in the presence of a large excess of ascorbic acid (AA) demonstrates this material’s potential for use in electrochemical biosensors.