Static and dynamic light scattering of poly‐(α‐methyl styrene) in toluene in the dilute region

Abstract

AbstractThe scattered intensity function S(q, c) and the intermediate scattering function S(q, c, τ) of poly‐(α‐methyl styrene) (Mω = 5.71 × 105, 1.17 × 106, and 2.96 × 106) in toluene in the dilute concentration region were measured as functions of concentration and scattering vector q. In infinitely dilute solution, the intensity function S(q, 0) agrees well with the Debye function for u < 7, where u is (qRg)2. At finite concentration S(q, c) varies from its thermodynamic value at low u to the single chain value at high u. Theoretical calculations of S(q, c) are in quantitative agreement with the observed scattering function in very dilute solutions. The intermediate scattering function S(q, c, τ) is a single exponential decay with decay rate Dmq2 for u ≪ 1. For u > 1, S(q, c, τ) is nonexponential, and when analyzed with a discrete inversion method, yields a bimodal distribution of decay rates. Both components are well represented as single exponential decays. D0 can be obtained from the slower component. The decay rate of the faster component is a continuous function of u and approaches q2 dependence at high u.