title: Insights into photoinduced sol-gel polymerization: an in situ infrared spectroscopy study.
abstract: Photoacid-catalyzed sol-gel polymerization is now recognized as a powerful single-step synthetic approach to the synthesis of hybrid films, which can be distinguished from conventional sol-gel methods by higher reactivity and a solvent-free process. Despite its utility, the mechanism is not yet understood, in particular what chemical, physical, and photochemical parameters determine the precise sequence, kinetics, and advancement of this UV inorganic photopolymerization. Here, using mainly transmission real-time Fourier transformed infrared (RT-FTIR) spectroscopy, we characterize in situ the hydrolysis-condensation reactions of oligomeric silicon alkoxides and the formation of byproducts. Systematic review and assessment of numerous processing variables (relative humidity, film thickness, precursor structure, nature, and the concentration of photoacid generator) prove that the reaction kinetics are controlled by the two independent phenomena: the intrinsic chemical reaction rates and the water vapor permeation into the film.
authors.affiliation: Laboratory of Photochemistry and Macromolecular Engineering, University of Haute-Alsace, ENSCMu, Mulhouse Cedex, France.
authors.forename: Héloïse
authors.initials: H
authors.lastname: De Paz
authors.forename: Abraham
authors.initials: A
authors.lastname: Chemtob
authors.forename: Céline
authors.initials: C
authors.lastname: Croutxé-Barghorn
authors.forename: Didier
authors.initials: D
authors.lastname: Le Nouen
authors.forename: Séverinne
authors.initials: S
authors.lastname: Rigolet