Influence of the addition of organo-montmorillonite nanofiller on cross-linking of polysiloxanes - FTIR studies.

The main aim of the present work was to investigate the effect of organo-montmorillonite nanofiller on the cross-linking process of polysiloxane. Two series of model polysiloxane nanocomposites were prepared by incorporating organoclay at different amounts such as 0, 1, 2, 4, and 8 wt% in relation to the weight of the polymer matrix. Poly(methylhydrosiloxane) (PMHS) was cross-linked with two linear vinylsiloxanes of different chain lengths between functional end-groups through hydrosilylation. This reaction was carried out in the presence of Karstedt's catalyst at equimolar ratios of reactive groups. Fourier-transform infrared (FTIR) spectroscopic measurements obtained during the cross-linking processes as well as for the reaction products revealed that the rate of hydrosilylation and its efficiency are influenced by the type of the cross-linking agent used and the amount of organo-montmorillonite introduced into the polysiloxane network. Quantitative analysis of the recorded FTIR spectra showed that as the amount of nanofiller in the polysiloxane matrix increased, the rate and efficiency of the cross-linking process decreased. Swelling measurements confirmed that the increase in the amount of unreacted Si-H groups in the system resulted in a lower cross-link density of the studied materials. Furthermore, X-ray diffraction and transmission electron microscopy were performed to determine the nature of dispersion of organoclay within the studied systems.