Nanocomposites based on copolymers of fluorinated imide and polyhedral oligomeric silsesquioxane macromonomer: microstructure and morphology studies

摘要

Towards the development of copolymeric nanocomposites, N-3(trifltioromethyl)phenyl-7-oxanorbomene-5,6-dicarboximide (TFI) monomer and a macromonomer of polyhedral oligomeric silsesquioxane (POSS) were synthesized. Ring-opening metathesis polymerization to copolymerization of specified proportions of the two co-monomers was carried out. All the monomers and polymers were characterized using Fourier transform IR analysis and ~1H and ~(29)Si NMR. Gel permeation chromatography shows that copolymeric nanocomposites have a lower average molar mass than a homopolymer of TFI (HTFI). TGA shows that the thermal stability of the copolymer is inversely proportional to the proportion of POSS units. DSC studies have demonstrated that the glass transition temperature (T_g) of a nanocomposite possessing 25 wt% POSS is at a higher temperature (180°C) than that of HTFI (175 °C). Transmission electron microscopy and AFM images of copolymers are consistent with the self-assembled spherical aggregation of POSS units, while X-ray diffraction studies have confirmed the homogeneous dispersion of the same units within the nanocomposites.