KINETICS OF PHASE-SEPARATION BY SPINODAL DECOMPOSITION IN MIXTURES OF TELECHELIC HYDROXY-TERMINATED POLYISOBUTYLENE AND POLY(TETRAHYDROFURAN)

Time-resolved light scattering has been employed to study the phase separation kinetics of hydroxy-terminated polyisobutylene (HO-PIB-OH)/poly(tetrahydrofuran) (HO-PTHF-OH) mixtures. A coexistence curve was constructed by conventional cloud-point measurement. The system reveals an upper critical solution temperature (UCST) with a maximum at 75 wt% HO-PTHF-OH at 43-degrees-C, and it is reversible. Several temperature quench experiments with the 75 wt% HO-PTHF-OH mixture were carried out from a single-phase region (52-degrees-C) to a two-phase region (38, 36, 34, and 32-degrees-C). Dissolution studies were undertake from 30-degrees-C to a single-phase region at 45, 47, 49, and 51-degrees-C. The spinodal temperature was 42-degrees-C for the 75 wt% HO-PTHF-OH mixture. The time evolution of scattering profiles was analyzed by the linearized Cahn-Hilliard theory for the initial stage of spinodal decomposition (SD) and by dynamic scaling laws for the late growth regime of SD. The possibility of perturbing phase separation by the onset of crystallization of HO-PTHF-OH is discussed.