Abstract
Synthesis of polysiloxane and the blending of polysiloxane with novolac type phenolic resin, PMMA and epoxy were studied. Differential scanning calorimetry (DSC), solid state magnetic nuclear resonance (NMR) and Painter-Coleman Association Model (PCAM) were used to study the miscibility, thermodynamic properties and the molecular motion of the organic-inorganic materials. The first part of this thesis is focused on the miscibility, thermodynamic properties and molecular motion of novolac type phenolic resin blended with poly(dimethylsiloxane adipamide) (PDMSA) synthesized in laboratory. PDMSA is miscible with novolac type phenolic resin, due to the strong intermolecular hydrogen bonding present in the polymer blend. The Gibbs free energy of PDMSA/phenolic blend is negative throughout the whole blend composites that simulated from the PCAM model. The solid state NMR was used to study the molecular motion of PDMSA/phenolic blend, which is dependent on the free volume of phenolic blend. The solid state NMR results (i.e. chemical shift, T1r time relaxation, and efficiency of cross polarization) can interpret the phenonmena of the molecular motion in the PDMSA/phenolic blend. The second part of this study aims to prepare poly(dimethylsiloxane)-urethane-co- poly(methyl methacrylate)（PMMA-urethane -co-PDMS）graft copolymers which possess better toughness and higher thermal stability compared with neat PMMA. Confirmed by IR、NMR、GPC、Soxhlet extraction and swelling measurement, slightly cross-linked PMMA-co-PDMS urethane graft copolymers based on MMA monomer and PDMS urethane-methacrylate macromonomers with two diisocyanates: 2,4-TDI and m-XDI have been successfully synthesized. Results that the structural difference in the diisocyanates affect the compatibility of PDMS-urethane and PMMA segments. The strength of hydrogen bonding between urethane and ester groups is close to that between urethanes, hence PDMS-urethane is miscible with PMMA in 2,4-TDI system. However, the strength of hydrogen bonding between urethane and ester groups is smaller than that between urethanes, which causes phase separation in m-XDI system. Impact strength of 2,4-TDI system（22.21J/m）is better than that of pure PMMA and m-XDI system. Thermal stability of copolymer is better than pure PMMA, and that of copolymer is increasing with macromonomer content. The third part of this thesis investigates the synthesis of aromatic amine-terminated polydimethylsiloxane toughened novolac type epoxy. The miscibility of modified epoxy is improved by blending low content (7phr) of polysiloxane. The polysiloxane can completely disperse in the epoxy matrix that reduces the glassy transition temperature and the degree of crystallinity. From the results of curing kinetics, the addition of polysiloxane will decrease the collision factor and total heat of reaction, and increase the active energy of reaction increase. The polysiloxane increase the enthalpy relaxation of modified epoxy, lower shrinkage and increase thermal stability of curing modified epoxy matrix.