MEAN-SQUARE RADIUS FO GYRATION OF POLY(DIMETHYLSILOXANE) CHAIN WITH SIDE-GROUPS

Using the rotational isomeric state theory, the unperturbed mean-square radius of gyration [S2] for the polymer chain considering the effect of a pair of side groups is derivated. If the spatial dimension (or the mass) of side groups and the mass difference of skeletal atoms are ignored, the expression is reduced to that of Flory and so forth. As an example, the numerical calculation of [S2] is executed for unperturbed poly(dimethylsiloxane). The molecular weight dependence of the mean-square radius of gyration is [S2]/M = 7.82 x 10(-2) angstrom2 (g.mol)-1 which is in agreement with the experimental data. [S2]/M = (7.7 +/- 0.3) x 10(-2) angstrom2 (g.mol)-1.