Studies of linear polymer dimensions of poly(4‐chlorostyrene) in various solvents around the θ temperatures by intrinsic viscosity

Abstract

AbstractIntrinsic viscosities of poly(4‐chlorostyrene) solutions in isopropyl‐benzene and n‐propylbenzene at temperatures above and below the theta (θ) temperatures of these solvents were measured using a capillary viscometer. The viscosity measurements were performed on three poly(4‐chlorostyrene) samples having molecular weights (M̄;v) 1.75 × 106, 6.5 × 105 and 2.7 × 105. A smooth and continuous contraction below the θ temperatures was observed for both solvents. The temperature dependence of [/eta] can be represented by a master curve in a plot of α3/eta|/tau|M1/2 (g1/2 mol−1/2) versus |/tau|M1/2 (g1/2 mol−1/2), where α/eta = [/eta(T)]/[/eta(θ)]1/3 is the expansion factor and /tau = (T ‐ θ)/T is the reduced temperature. A universal plot of reduced viscosity size (α/eta) versus reduced blob parameter (N/Nc) shows the achievement of collapsed state for T<θ. The prediction of thermal blob theory is also verified for T > θ. The temperature dependence of intrinsic viscosity, both below and above the θ temperature, exhibits similar behaviour to the temperature dependence of dipole moments for both of these solvents.