Hybrid networks derived from isosorbide by means of thiol-ene photoaddition and sol-gel chemistry

New bridged silsesquioxanes derived from isosorbide were synthesized, according to the sol-gel process, by acidic or basic hydrolysis and condensation of a bis-trimethoxysilyl precursor. The latter was prepared by thiol-ene photoaddition of 3-(trimethoxysilyl)-1-propane thiol on diallyl isosorbide ether synthesized by a phase-transfer-catalyzed reaction of allyl bromide with isosorbide. The structure of those hybrid networks prepared according to a sol-gel process was investigated by Si-29 solid-state NMR and X-ray diffraction experiments. Acid hydrolysis leads to the formation of randomly branched structures while basic catalysis promotes the creation of clusters. The anisotropic character of the hybrid networks was evidenced by cross polarized optical light observations (birefringence), demonstrating an organization at the micrometric-scale. These hybrid networks derived from isosorbide showed a thermal stability up to 360 degrees C. (C) 2014 Elsevier Ltd. All rights reserved.