IMPROVED EXPRESSION OF THE MEAN-SQUARE RADIUS OF GYRATION .2. POLY(1,1-DISUBSTITUTED ETHYLENE)S

The mean-square radius of gyration of poly(1,1-disubstituted ethylene) s is calculated according to a method already developed for poly(methy l methacrylate), poly(alpha-methylstyrene) and polyitaconate. During t he derivation both the effect of side groups and the masses of skeleta l atoms were taken into account. A hypothetical polymer chain was intr oduced, in which the mass of the substituents on every C-alpha was con sidered to be concentrated in their center of mass, and the virtual si de bond vector runs from C-alpha to this center. The mean-square radiu s of gyration of poly(1,1-disubstituted ethylene)s consists of two par ts, one of which is the mean-square radius of gyration of the hypothet ical molecule described before and the other is related to the geometr ical characteristics of the side groups. Numerical calculations indica ted that the dependence of the mean-square radius of gyration of poly( 1,1-disubstituted ethylene)s on the molecular weight is analogous to t hat of vinyl polymers, [S-2] = aM(b), where a and b are constants char acteristic of the polymer.