Analysis of the Phase Separation Induced by a Free-Radical Polymerization in Solutions of Polyisobutylene in Isobornyl Methacrylate

E.R. SOULÉ; G. E. ELICABE; J. BORRAJO; R.J.J. WILLIAMS

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

AMER CHEMICAL SOC

Año: 2007 vol. 46 p. 7535 - 7542

0888-5885

We analyze a polymerization-induced phase separation taking place in solutions of a polymer dissolved in avinyl monomer undergoing an isothermal free-radical polymerization. The selected system was a solution ofpolyisobutylene (PIB) in isobornyl methacrylate (IBoMA). Cloud-point curves for PIBs of different molarmasses were fitted with the Flory-Huggins equation stated for a 3-component system. Phase separation wasanalyzed for two different PIBs at off-critical compositions. In a comparison of experimental values of thevolume fraction of dispersed phase with those predicted by the coexistence curves, it was found that thesystem evolved close to equilibrium during an initial stage. But phase separation stopped at intermediatemonomer conversions as assessed by scanning electron micrographs of partially converted materials. Theevolution of the size distribution of dispersed domains was obtained from the fitting of light scattering (LS)spectra. Average sizes predicted by LS and measured in scanning electron micrographs were in rough agreement.