Effect of gamma Irradiation on Latex Film Dissolution

Latex films have been prepared by annealing pyrene (Py)-labeled poly(methyl methacrylate)-polyisobutylene particles at the glass transition temperature (100 degrees C). These films were then irradiated by gamma rays from (60)Co in a gamma cell at room temperature at various dose rates (rad/h). Before dissolution the films were annealed at 200 degrees C for a 30 min time interval to complete the film formation process. Steady-state fluorescence techniques were used to monitor the dissolution of irradiated latex films. Dissolution of films in a chloroform-heptane (80%-20%) mixture was monitored in real time by the Py fluorescence intensity change. Relaxation constants, k(0), and dissolution coefficients, D(d), of polymer chains were measured. Two different regimes of D(d) values were observed during dissolution, which are related to two different molecular weight distributions caused by scission and branching of polymer chains when they were irradiated and annealed. Copyright 2001 Academic Press.