Nanosize control of final products from sol-gel reactions for optical waveguides

Abstract

We determined the mechanism and the nanosize products of a sol-gel reaction with diphenylsilanediol (DPD) and 3-methacryloxypropyltrimethoxysilane (MEMO) precursors for synthesizing an optical waveguide material. From the first-principles calculation, we found that diphenyldimethoxysilane (DPDM) and 3-methacryloxypropylmethoxysilanediol (MEMDO) are generated through the first two steps, and we also determined that the reaction pathway could be modified by the presence of H2O released from a catalyst such as Ba(OH)2 · H2O. In the final step, condensation between a MEMDO hydroxyl and a DPDM methoxy occurs, generating a DPDM-MEMDO dimer and CH3OH molecule as products. In a similar fashion, the DPDM of the DPDMMEMDO dimer can condense with the MEMDO of another DPDM-MEMDO dimer to increase the chain, but its reaction rate of 2.8×10-11 per second is predicted to be about five times smaller than that between DPDM and MEMDO. This implies that the reaction rate becomes smaller for larger nanostructures.