Pyrolysis mechanism and electrical properties of 3D-hybrid organic–inorganic materials based on zirconium oxides-hydroxides, 3-butenoates and vinyltrimethoxysilane

Abstract

This report is focused on the quantitative thermogravimetric–mass spectrometric (TG–MS) analyses and the electrical response of two hybrid organic–inorganic materials (HYP and HYPC), obtained reacting together nanoclusters of zirconium oxides-hydroxides with 3-butenoates and cross-linked with vinyltrimethoxysilane. HYP was cured at 363 K, while HYPC at 403 K. Condensation of the silanol groups, producing shrinkage, alcoholation and the release of 3-butenoic acid and methyl 3-butenoate are the main processes involved in the early stages of pyrolysis from 323 to 633 K. The nominal formula for the two samples with a fair degree of approximation was obtained by elemental analysis and quantitative TG–MS measurements. Morphology of HYP and HYPC is determined by high-resolution transmission electron microscopy. In both HYP and HYPC, the electric response is characterized by a molecular dipole relaxation detected at higher frequencies and an inter-domain polarization phenomenon revealed at the lower frequencies, due to the presence of charged interfaces between nanodomains with different permittivities. HYP material showed a further dipole relaxation at intermediate frequencies, which assists the charge migration process. HYPC, containing a smaller density of 3-butenoate groups, reveals a long-range charge migration event of mobile species by hopping processes between relatively stiff sites.