PREPARATION OF NANOBLEND POLYMER BY POLYMERIZATION IN POLYMER AND ITS NANO CELLULAR FOAMS

摘要

A new method of preparing polymer blends with nanoscale-islands is proposed. The polymethyl methacrylate (PMMA)/ polystyrene (PS) blend, which has PMMA islands dispersed in nanoscale order, was prepared by the method: dissolving MMA monomer and polymerizing the monomer in PS matrix could provide higher molecular weight of PMMA and create highly dispersed PMMA domains in PS matrix owing to gel effects and diffusion mixing. The resulting polymer blend was foamed with CO_2. Nanocellular foam could be prepared using the polymer blend morphology as a template where bubble nucleation was localized in PMMA domains. The effects of blend ratio, foaming temperature and depressurization rate on bubble diameter as well as bubble density were investigated. The higher depressurization rate at lower foaming temperature made cell diameter smaller and the density larger. The higher PS composition in blend made the density larger. The cell 40-50 nm in average diameter and 8.5×10~(14) /cm~3 was obtained as the finest nanocellular foams.