In situ polymerization of titanium alkoxides in polyvinylacetate

A new hybrid organic-inorganic material is obtained by the in situ polymerization of titanium isopropoxide in polyvinylacetate. The hydrolysis and condensation reactions of the alkoxide are carried out in a tetrahydrofuran solution, via a controlled sol-gel process which yields macroscopically homogeneous and transparent films. Small angle X-ray scattering allows for the determination of a composite structure of the films, i.e., a dispersion of 'titanium oxide' particles in the organic polymer matrix. The crosslinked nature of the resulting compounds is shown. Thus strong interactions exist between the polymer and the inorganic phase, avoiding a macroscopic phase separation. Those interactions are proved to be covalent links; it is therefore possible to crosslink chemically the thermoplastic polymer with the inorganic phase. Dynamical mechanical spectroscopy reveals the existence of two relaxations which might account for an interphase between polyvinylacetate and titanium oxide clusters.