Unperturbed Chain Dimensions of Poly(di-n-hexylsilane), Poly(methyl-n-propylsilane), and Poly(di-n-butylsilane)

摘要

Unperturbed chain dimensions of poly(di-n-hexylsilane) (PDHS), poly(methyl-n-propylsilane) (PMPrS), and poly(di-n-butylsilane) (PDBS) have been evaluated by a combined use of static light scattering, size exclusion chromatography (SEC), and SEC-multiangle laser light scattering. The #theta# solvents and characteristic ratios (C_ infinity 's) of the individual polysilanes wer determined as follows: PDHS, a mixed solvent of n-hexane (58.2 wt %) and 2-propanol (41.8 wt %) at 25 deg C and C_ infinity = 42.5; PMPrS, a mixed solvent of n-hexane (62.6 wt %) and 2-propanol (37.4 wt %) at 25 deg C and C_ infinity = 19.9; PDBS, n-hexane at 19.1 deg C and C_ infinity = 42.3. These C_ infinity values show that the polysilanes in the #theta# state are much more extended and rigid than ordinary carbon backbone polymers. On the basis of the results, the conformational characteristics of the three polysilanes are discussed by reference of their UV spectra.