Preparation Of Functional POSS-Based Polymer Hybrid Materials

Polyhedral Oligomeric Silsesquioxane (POSS) was a three-dimensional nano organic/inorganic hybrid molecule. POSS can composite with polymer at molecular level. POSS modified polymers have enhanced mechanical and thermal properties. Introducing POSS into the functional polymers, will bring the improvement in structure and performance of the copolymers, due to POSS's special structure and excellent dispersion in the hybrid materials.Several functional POSS-based polymer hybrid materials were synthesized, and the impact of POSS to different functional polymer was studied. Methacrylate Polyhedral Oligomeric Silsesquioxane (MAPOSS) was incorporated into poly(N-isopropylacrylamide) (PNIPAM) chains, and the thermosensitive and wetting properties of copolymers were studied. Octa(phenyl)sulfonic POSS (SOPS) was synthesized, and hollow silica spheres were prepared by calcining PS spheres coated with (poly (allylaminehydrochloride)/poly (styrene-4-sufonate))2/(PAH/SOPS)n. Chitosan/POSS hybrid membranes were prepared, and the influence of different functional groups of POSS and different preparation conditions on the morphology of hybrid membranes were studied.This thesis achieved some results as follows:(1) P(NIPAM-co-MAPOSS) copolymers were synthesized via in situ copolymerization of NIPAM and MAPOSS. The structure of copolymers was characterized by FTIR and 1H NMR. The thermosensitive properties of the P(NIPAM-co-MAPOSS) copolymer aqueous solution were studied by DSC. Lower Critical Solution Temperature (LCST) decreased when increasing the POSS content. The surface wetting properties of P(NIPAM-co-MAPOSS) copolymers with different POSS content were explored, which showed that water contact angle increased with raising POSS content.(2) Ocat(phenyl) sisesquioxane (OPS) was modified to introduce negative charges via sulfonation, SOPS, was confirmed by FTIR and 1H NMR. Poly(allylamine), PAH, and SOPS were layer-by-layer (LbL) assembled onto 400nm polystyrene (PS) spherical template. The regular growth of PAH/SOPS multilayers on sphere supports was confirmed by Zeta potential and dynamic light scattering. Subsequent calcination of the particles yields hollow silica spheres, and the size controlled by the number of SOPS layers.(3) Biopolymer chitosan/POSS nanocompo sites containing octaaminopropyl polyhedral oligomeric silsesquioxane (OapPOSS), octavinyl POSS (OvPOSS), octaepoxy POSS (epoxy-POSS) were successfully prepared by a simple solution-evaporation method. The morphology of the chitosan/POSS nanocompo sites was characterized with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is observed that chitosan/OapPOSS is the most homogeneous hybrid film of the three, partly due to the hydrogen bond between OapPOSS and chitosan chains. Mechanism of OapPOSS assembly with chitosan was proposed.