Xinfeng Wu

Mechanically Flexible and Multifunctional Polymer‐Based Graphene Foams for Elastic Conductors and Oil‐Water Separators

We present a novel strategy for the fabrication of ordered and flexible polymer-based graphene foams by self-assembly of graphene sheets on a 3D polymer skeleton. The obtained graphene foams show excellent mechanical, electrical, and hydrophobic properties, thus holding great potential as elastic conductors and oil-water separators.

Hyperbranched-polymer functionalization of graphene sheets for enhanced mechanical and dielectric properties of polyurethane composites

The incorporation of graphene sheets (GSs) into polymer matrices affords engineers an opportunity to synthesize polymer composites with excellent physical performances. However, the development of high performance GS-based composites is difficult because of the easy aggregation of GSs in a polymer matrix as well as the weak interfacial adhesion between GSs and the host polymer. Herein, we present a simple and effective route to hyperbranched aromatic polyamide functionalized graphene sheets (GS–HBA). The resulting GS-HBA exhibits uniform dispersion in a thermoplastic polyurethane (TPU) matrix and strong adhesion with the matrix by hydrogen-bond coupling, which improve the load transfer efficiency from the matrix to the GSs. Thus, the GS–HBA–TPU composites possess excellent mechanical performance and high dielectric performance. It has been demonstrated that the GS–HBA composite has higher modulus, higher tensile strength and higher yield strength, and remains at nearly the same strain at break when compared with the composites with graphene oxide, ethylene diamine-modified graphene, and hydrazine reduced graphene. In addition, the hyperbranched polymer chains allow construction of a large number of microcapacitors and suppress the leakage current by isolating the GSs in a TPU matrix, resulting in a higher permittivity and lower loss tangent for the GS–HBA composite in comparison with ethylene diamine-modified graphene, or hydrazine reduced-graphene composites.

Preparation of hyperbranched aromatic polyamide grafted nanoparticles for thermal properties reinforcement of epoxy composites

Epoxy nanocomposites with hyperbranched aromatic polyamide grafted alumina (Al2O3) nanoparticles as inclusions were prepared and their thermal properties were studied. The Al2O3 nanoparticles were firstly treated with a silane coupling agent to introduce amine groups, then grafting of the hyperbranched aromatic polyamide started from the modified surface. Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR) analysis proved hyperbranched aromatic polyamide grafted Al2O3 nanoparticles were successfully prepared by solution polymerization. Transmission electron microscopy (TEM) showed that there was a thin polymer layer on the Al2O3 nanoparticles surface, which contributes to the uniform dispersion of Al2O3 nanoparticles in epoxy matrix and the improvement of the interfacial interaction between Al2O3 nanoparticles and epoxy matrix. Thus the glass transition temperature, thermal stability, thermal conductivity and thermomechanical properties of nanocomposites were enhanced.

Enhanced thermal properties for epoxy composites with a three-dimensional graphene oxide filler

In this study, we report a simple and efficient method to prepare three-dimensional graphene oxide (3DGO) network by freeze drying and investigate the effect of 3DGO network on thermal properties of epoxy composites. It was found that the 3DGO network not only improved thermal conductivity, thermal stability, glass transition temperature and storage modulus of epoxy composites, but also reduced the thermal expansion properties of epoxy composites. For instance, the thermal conductivity value of epoxy composite with only 1.3 wt% 3DGO is 0.62 Wm-1K-1, increased by 148 % in comparison with that of the neat epoxy (0.25 Wm-1K-1).

Enhanced thermal transport performance for poly(vinylidene fluoride) composites with superfullerene

High thermal conductive polymer composites have recently attracted much attention, along with the quick development to the electronic devices toward higher speed. The addition of high thermal conductive fillers is an efficient method to solve this problem. Here, we introduced superfullerene (SF), a novel zero-dimensional carbon-based filler, and incorporated into PVDF by a solution method. The effects of SF filler on the thermal conductivity of PVDF composites were systematically investigated. It was found that PVDF composites exhibited an improvement in thermal conductivity at a low SF loading. PVDF composites with only 5 wt% SF filler present the thermal conductivity value of 0.365 Wm-1K-1, which is as much as 121 % enhancement in comparison with that of neat PVDF. In view of the excellent thermal transport performance, the composites may enable some applications in thermal management in the future.

Improved thermal properties of epoxy composites filled with thermotropic liquid crystalline epoxy grafted aluminum nitride

A liquid crystalline epoxy (LCE) grafted AlN particles (LCE-g-AlN) were fabricated and then incorporated these into epoxy matrix to obtain the composites. The structure of LCE-g-AlN was characterized by Fourier-transform infrared (FT-IR), nuclear magnetic resonance (NMR), thermal gravimetric analyses (TGA), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC). The morphology and thermal properties of composites were systematically investigated. The morphology of the epoxy/LCE-g-AlN composites performed by scanning electron microscopy (SEM) indicated a homogeneous distribution of the LCE-g-AlN particles in epoxy. Moreover, the glass transition temperature (Tg), thermal stability, thermal conductivity and dynamic mechanical properties of composites showed a significant improvement due to the good miscibility and improvement of the interfacial interaction between LCE-g-AlN particles and epoxy matrix.

Functional graphene for high dielectric performance polymer composites

Graphene, a two-dimensional monolayer of carbon atoms with conjugated honeycomb structure, has received broad interest owing to its unique physical properties such as high electrical conductivity, excellent mechanical strength, and large surface area. One promising route to harnessing these properties for applications is to improve dielectric properties of polymer by adding graphene sheets at low loading. However, graphene sheets are prone to aggregate, resulting that the improvement of dielectric properties of graphene-based composites is significantly compromised or even unavailable. In this study, we have investigated the effect of functional of graphene sheet on the dielectric properties of the compoistes. The functionalized graphene-based polymer composites show higher dielectric constant and low dielectric loss when compared with graphene composites.