Rheological and Rheooptical Studies of Poly(alkylsilanes)

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Rheological and rheooptical properties of poly(di-n-hexylsilane) were investigated in oscillatory and steady-shearing experiments. The samples consisted of concentrated solutions up to 6 wt% of a very high molecular weight polymer (Mw = 4.6 × 106) dissolved in decalin. Experiments showed that the flowinduced shear and normal stresses were linearly related to the birefringence and that the constant of proportionality-the stress-optical coefficient-was larger than that of typical polymers. The enhanced stress-optical coefficient is a result of both the intrinsic rigidity of the polysilane chain and the higher polarizability of the σ-conjugated electrons. This result is similar to that found recently for a π-conjugated polymer. Additional results on the concentration dependence of various rheological properties are reported. © 1991, American Chemical Society. All rights reserved.