Nuclear Reaction Analysis Studies on the Interface Formation in Polymer Mixtures

ABSTRACTWe have measured the composition profile between two polymer phases above and below their critical temperature for phase separation Tc, using the 2H(3He,4He)1H nuclear reaction in a direct profiling technique. Above Tc, we verify the “thtrmodynamic slowing down” effects on interdiffusion close to the critical point. Pelow Tc, we find that the width of the interface grows with time to a finite limiting value. The variation of this limiting value, as Tc, is approached from below is in good agreement with the predictions of mean-field theories. The time dependence of the initial interfacial broadening below Tc has been found to be significantly slower than t1/2.