Polymers Composited With Multi-scale Organosilicone Based Nanoparticles

The properties of nanocomposites were affected by several factors. Of which, dispersion of nanoparticles, interactions between nanoparticles and polymer matrix, dimensions of the nanoparticles were particularly important. By considering the features of different nanoparticles and adjusting the interactions between nanofiller and matrix, nanocomposites with high performance could be obtained. Here the features of the nanoparticles mainly contained the dimensions and the surface functional groups. The dimensions of nanoparticles could be one dimensional nanomaterials like nanotubes, two dimensional nanomaterials like clay or graphene and three dimensional nanomaterials like silica or POSS. The surface functional groups of nanoparticles could be reactive or non-reactive. Research on the interaction of the nanoparticle dimensions and the interactions between nanofiller and matrix could be of great significance.(1) N-Phenylamino-methyl POSS was three dimensional reactive nanoparticle. Considering the reactivity, it was incorporated to modify the PSMA resin. A series of crosslinked hybrids were prepared using various amounts of POSS as nano-scale crosslink agent. The hybrids showed no macro-phase separation even when the POSS concentration was up to30wt%. HRTEM measurements showed the POSS was nano scale separated in PSMA matrix. DSC results indicated that Tg increased with the addition of POSS. DMA revealed the storage modulus of the hybrids at high temperature was much improved compared with that of neat PSMA, especially with high POSS loadings. TGA revealed the values of Td,25%to Td,70%of the hybrids were increased and the char yields were much improved. The enhanced properties were ascribed to the synergetic effects of PSMA and POSS. Because of the good compatibility between POSS and PSMA, POSS as a crosslinker could be dispersed into PSMA matrix in nano scale. PSMA chains would be restricted by the nano scale crosslinker, and resulted in the great enhancement of mechanical and thermal properties.(2) The vinyl-silica nanoparticles were three dimensional nanoparticles, which had good compatibility with polymers due to the rich surface organic functional groups. Considering the good dispersion of vinyl-silica nanoparticles in polymers and its non-reactivity, we incorporated the nanofillers into polypropylene (PP) and polylactic acid (PLLA). SEM indicated that vinyl-silica nanoparticles were homogeneously dispersed in both polymers. For PP, Vinyl-silica nanoparticles not only worked as rigid particles, but also brought new energy-dissipating mechanisms for the nanocomposites. Simultaneously improved strength and toughness of the nanocomposites was confirmed by tensile test and notched impact test. Also, the enhanced thermostabilization was proved by TGA measurement. For PLLA, the well dispersed vinyl-silica nanoparticles worked as heterogeneous nucleation agent. The improvements of crystallinity and crystallization rate of PLLA were both confirmed by DSC.(3) Graphene was a two dimensional nanoparticles with large specific surface area. When composited with polymers, it tended to aggregated. Here we functionalize the graphene with N-(aminoethyl)-aminopropyltrimethoxysilane (KH792) to improve its dispersion in organic solvent and polymer matrix. With the incorporation of the KH792-RGO, the storage modulus of the composite was largely increased in the rubber state.0.5wt%addition of KH792-RGO dramatically increased the storage modulus of PLLA around Tg by one order of magnitude compared with neat PLLA (from20to300MPa). Meanwhile, the heat distortion resistance of PLLA/KH792-RGO was greatly improved as well. Formation of a graphene network in the composites was considered to be the main driving force of the outstanding performance for the nanocomposites.