Conformation change of nanosized silicon-organic polymer oriented into ordered nanoporous silicas

We present a study of fluorescence (5-250)K and FTIR spectra of poly(di-n-hexylsilane) incorporated into nanoporous silicas (MCM-41 and SBA-15 types) and SiO2 aerosil. It is shown that the essential local conformation change of the polymer chain occurs only for the polymer embedded into and oriented in small-diameter pores with a large number of Si-OH groups on the surface of the walls. The competition between the polymer-surface and the polymer-polymer interactions leads to the restructuring of a polymer incorporated into the large pores of SBA-15 where the separarate polymer chain having trans- and gauche-conformations as well as the aggregates can be found. The presence of the gauche-conformation is confirmed by the shift of CHa2 and CHs2 stretching vibrations and, additionally, by the redistrubution of their intensity with increasing the pore diameter.