Viscometric Study of Poly(ester Urethane) Solutions: 2. Influence of Hard-Segment Composition on the Unperturbed Dimensions

Abstract

Using viscometry, we have studied the dilute solution property of segmented poly(ester urethane)s obtained by the reaction of aromatic diisocyanates with poly(ethylene glycol)adipate and 4,4′-dihidroxydiethoxydiphenyl sulphone as chain extender, using a multistep polyaddition process. A new method proposed by Qian et al. was utilized for the determination of unperturbed dimensions of poly(ester urethane)s having different hard segments by the measurement of the intrinsic viscosity at non-theta conditions only. The influence of the hard segments on the unperturbed dimensions of these polymers was observed. The diisocyanates with methyl substituents in the hard segments, such as 2,4-tolylene diisocyanate, have smaller unperturbed dimensions compared with the samples containing 4,4′-methylene diphenylene diisocyanate, which are believed to possess significant chain rigidity because of the high cohesive energy and bulkiness of the benzene ring.