Formation of Polymethylsiloxanes with Alkyl

Side Groups

O. Mukbaniani ¹, G. Titvinidze ^1,2, Tamara Tatrishvili ¹ , Nino Mukbaniani ¹
Witold Brostow ²  and Dorota Pietkiewicz ²

1Department of Macromolecular Chemistry, Ivane Javakhishvili University, Tbilisi, Georgia 0128

2Laboratory of Advanced Polymers and Optimized Materials (LAPOM),
Department of Materials Science and Engineering, University of North Texas, Denton, Texas 76203-5310

ABSTRACT

Hydrosilylation of a,o-bis(trimethylsiloxy)-methylhydrosiloxane to alkenes in the presence of a catalyst
was performed at several temperatures (30–708C). Combtypemethylsiloxane oligomers with various alkyl substituted
groups in the side chains have been obtained. Not all active BSi H groups participate in the reaction. The reaction
order, activation energies, and rate constants have been determined. The synthesized oligomers were characterized
by 1H, 13C, 1H COSY NMR, and FTIR spectroscopy. Calculations using the quantum-chemical semiempirical AM1 method
for modeling reaction between methyldimethoxysilane [Me(MeO)2SiH] and hexene-1 were performed to evaluate
possible reaction paths. For all initial, intermediate, and final products, enthalpies of formation as a function of the distance
between BC SiB bonds are calculated. The hydride addition is energetically more favorable according to the anti-
Markovnikov rule than according to the Markovnikov rule. Comb-type oligomers were characterized by gel-permeation
chromatography, differential scanning calorimetry, thermogravimetry,and wide-angle X-ray diffractometry.