Polymerization of 3-cyanopropyl (triethoxy) silane: A kinetic study using gas chromatography

Gas chromatography (GC) was used to study the kinetics of the 3-cyanopropyl triethoxysilane (CTES) polymerization. The reaction is a consecutive complex reaction that depends mainly on the kinetics of the first hydrolyzed leaving group. The activation energy of CTES hydrolysis is 20 and 58kJ mol(-1) in alkaline and acidic media, respectively. The activation energy of ethanol production ranged from 22 to 55kJ mol(-1) according to the catalyst type and concentration. Generally, the reaction is an endothermic reaction in an acidic medium, whereas it is exothermic in an alkaline medium, depending on the catalyst concentration. Moreover, the reaction is spontaneous at high temperatures in an acidic medium. The rate constant is related to the catalyst concentration with empirical formulas depending on the Arrhenius equation. The rate constant increases non-linearly (to the power 2) with the concentration of water in an acidic medium, whereas it behaves differently in an alkaline medium and depends on the initial concentrations of CTES and the catalyst.