Study of Linear Poly(p-chlorostyrene)–Diluent Systems. II. The Conformations in Poly(p-chlorostyrene)–Endothermic Solvent (ethylbenzene) and Poly(p-chlorostyrene)–Exothermic Solvent (t-butyl acetate) by Light and X-Ray Small-Angle Scatterings

Abstract

The conformations of poly(p-chlorostyrene) (PPCS) in endothermic solvent (ethylbenzene, θU=−14.7°C) and in exothermic solvent (t-butyl acetate, θL=65.4°C) were determined by light and x-ray small-angle scattering on the condition that the molecular sizes were equal as a whole (i.e., at 30°C). θU is the theta temperature of the endothermic system and θL that of the exothermic one. The values of the radius of gyration 〈s2〉z1/2 and the second virial coefficient A2 obtained from light-scattering measurements were 2.23×10−6 and 5.56×10−5 for PPCS–ethylbenzene system, and 2.18×10−6 and 5.55×10−5 for PPCS–t-butyl acetate system, respectively.In X-ray scattering measurements, both the pure solvent (after the absorption correction and the corresponding monomer solution which had the same numbers of chlorine atoms as the PPCS solution, were employed as substances for the standard subtraction to obtain a excess scattering from the solution. Differences between the two subtraction methods appeared at angles larger than about 3°. 1 and 2% solutions were measured to take into account of the concentration dependences. The effect on the scattering curve was negligible at angles more than 0.4°. The smearing effect of the slit was analyzed according to the procedure of Schmidt. The determination of the persistence length a was possible after elimination of the cross-section factor. The values of persistence length a and the radius of gyration of cross-section factor Rq were comparable with those of polystyrene and its derivative in the published data according to Kratky, et al The a values obtained from X-ray small-angle scattering were somewhat smaller than tha values calculated from the hydrodynamic length L and the radius of gyration 〈s2〉z1/2 assuming a Gaussian coil. The values of a and Rq seem to be little affected in both endothermic and exothermic systems. However, differences of the conformations in the two systems appeared in the rod-like region of the scattering curve.