Dissolution of latex films after gamma-ray treatment

Latex films were prepared by annealing pyrene (Py)-labeled poly(methyl meth acrylate) particles at glass-transition temperature (100 degreesC). These f ilms were then irradiated by gamma -rays from Co-60 in a gamma cell at room temperature at the same dose rate (rad/h) for 30 min. Before dissolution f ilms were annealed at elevated temperatures for a 30-min time interval to c omplete the film formation process. Steady-state fluorescence (SSF) techniq ue were used to monitor the dissolution of these irradiated latex films. Th e dissolution of films in chloroform-heptane (80-20%) mixture was monitored in real time by the Py fluorescence intensity change. Relaxation constants k(0) and desorption coefficients Dd of polymer chains were measured. It wa s observed that both D-d and k(0) values first increased and then decreased by increasing the annealing temperature. (C) 2002 John Wiley & Sons, Inc.