Interphase bonding in organic–inorganic hybrid materials using aminophenyltrimethoxysilane

Several types of silica and titania-aramid hybrid materials were prepared using a sol–gel process. The aramid chains were prepared by the reaction of a mixture of m- and p-phenylene diamines and terephthaloyl chloride in dimethylacetamide. Addition of different amounts of tetraethoxysilane and tetrapropylorthotitanate in the polymer solution, and their subsequent hydrolysis-condensation yielded silica and titania networks, respectively, in the aramid matrix. The chemical bonding between the organic and inorganic phases was achieved by end-capping the aramid chains with aminophenyltrimethoxysilane. In-situ hydrolysis/condensation of tetraethoxysilane or tetrapropylorthotitanate along with that of aminophenyl-trimethoxysilane was carried out to produce silica and titania networks chemically bonded to aramid chains. Thin transparent and tough films containing up to 20 wt% of metal oxides were prepared. The storage and the loss moduli as a function of temperature were measured using dynamic mechanical thermal analysis. A greater shift in the α-relaxation associated with the glass transition temperature (Tg) was observed in case of chemically bonded ceramers as compared to the unbonded and has been explained in term of greater interaction between the organic and inorganic phases.