| In recent years, a special interest on the synthesis of inorganic/polymer nanocomposites have emerged because of their unique properties with the combination of both inorganic nano-fillers and organic polymers. The polymer nanocomposites incorporated by inorganic nano-fillers exhibit improved mechanical, optical, electrical, and other properties, which have a wide range of applications, such as paints, optical devices, waste water treatment, catalysts and drug carriers. However, inorganic nano-fillers have a strong tendency to agglomerate with poor dispersibility in the polymer matrix, which often lead to achieving undesired performance for the nanocomposites. Therefore, it is essential to improve the dispersibility of nano-fillers in the polymer matrix, as well as optimize the interfacial interaction between the fillers and matrix at the nano-scale in order to achieve synergistic enhancements. To solve these key problems, based on the colloidal dispersion system, from improving the interfacial interaction and compatibility between the fillers and matrix, two kinds of typical nano-fillers（graphene and TiO2） were selected for preparation of highperformance inorganic/polymer nanocomposites by employing a variety of novel methods. The details are illustrated as follows:（1） GO was synthesized using a modified Hummers’ method, and then covalently functionalized by hydroxypropyl methacrylate（HPMA） monomer to obtain a vinyl-grafted GO. Afterwards, the functionalized GO was treated via miniemulsion polymerization in the presence of MMA to obtain PMMA-g-GO composite latex. The results from the FTIR spectra and XPS analysis indicate that the obtained GO contains a variety of oxygen functional groups and is successfully functionalized by HPMA via an esterification reaction. TEM results show the PMMA particles are grafted to the edges of the GO sheets, with sizes ranging from 70 to 110 nm. Moreover, with the incorporation of GO, the glass transition temperature（Tg） and thermal stability of composite latexes are remarkably enhanced with respect to the neat PMMA latex.（2） PMMA/GNSs nanocomposites with homogeneously dispersed GNSs in the polymethyl methacrylate（PMMA） matrix were prepared via combining miniemulsion polymerization and melt blending method. First, the PMMA-g-GO composite particles were prepared using the miniemulsion process, and then was melt blending with the commercial PMMA granules, wherein in-situ thermal reduction of GO in the matrix achieved simultaneously. The results show that the GNSs exhibit exfoliated morphology and good distribution in the obtained nanocomposites. The storage modulus of the nanocomposites increases by 45%, while the Tg increases by 7.5 °C at 1.5 wt.% GNSs loading. A 37.9% enhancement in tensile strength and a 61.4% increase of Young’s modulus with respect to the polymer matrix are achieved by incorporating only 1.5 wt.% GNSs loading. Moreover, the experimental derived Young’s modulus agrees well with the theoretical prediction.（3） A general methodology, namely, colloidal shear-driven aggregation process, has been developed for preparing nanocomposites with uniform, random distribution of nanofillers in polymer matrices, while avoiding fillers aggregation. Its feasibility has been demonstrated using stable binary colloids composed of GO sheets and poly-vinylidene fluoride（PVDF） nanoparticles（NPs）. On the other hand, the PVDF NPs are shear-active（i.e., aggregation occurs under intensive shear）, while the GO sheets are shear-inactive. It is found that when the two suspensions are mixed and the resulting binary colloid is forced to pass through a microchannel（MC） device（at a very high shear rate, G = 1.2×106 s-1）, the shearinactive GO sheets are captured and well distributed inside the PVDF NP clusters or gels. In addition, it is shown that in order to have 100% capture efficiency for the GO sheets, a minimum solid content of the binary colloid is required, which can be identified experimentally as the minimum leading to gelation after passing through the MC only one time.（4） High-performance GO/PVDF composite membrane materials were synthesized by colloidal shear-driven aggregation process. First, mixed the GO dispersion and PVDF nanoparticle dispersion to obtain a homogeneous and stable binary colloid, and then forced the GO/PVDF binary colloid to pass through the microchannel device（z-MC） one time at high pressure to generate ―frozen‖ solid gels. In such a process, the GO sheets were exfoliated and homogeneously dispersed in the gel matrix. At last, the dried gels was hot pressed to get GO/PVDF composite membranes. The results show GO sheets exhibit exfoliated morphology and good dispersibility in the PVDF nanocomposites. The incorporation of GO sheets into the PVDF matrix can effectively improve the melting temperature, crystallization temperature, and thermal decomposition temperature. In addition, the oxygen barrier properties of the GO/PVDF composite membranes are remarkably enhanced with respect to the neat PVDF membrane. With a GO loading at 2.0 wt %, its oxygen permeability coefficient reduces by 76%.（5） TiO2 nanoparticle/poly（MMA–BA-MAA） nanocomposite colloidal microspheres with core-shell morphology were prepared via in-situ emulsion polymerization. TiO2 nanoparticles was firstly modified by A-151 in liquid media to get ―seed‖ containing vinyl groups, and then MMA, BA, MAA monomers were polymerized on the surface of modified TiO2 particles, to obtain TiO2 core/polyacrylate shell nanocomposite particles. The results indicate A-151 is covalently bonded onto the surface of TiO2 nanoparticles and the amount of grafted A-151 is 3.0%, the dispersibility of modified TiO2 nanoparticles is obviously improved. The composite microspheres exhibit obvious core-shell structure morphology, with the core TiO2 particles surrounded by a uniform 1015 nm thick polymer shell. Furthermore, the TiO2 nanoparticles are homogenously monodispersed in the polymer matrix, without apparent aggregation. An obvious Tg enhancement of composite membrane is obtained with the addition of TiO2 nanoparticles. |
