Water vapor transmission rate of polymer hybrid latex poly-(St-co-BA-co-MMA) synthesized via miniemulsion polymerization technique with montmorillonite as filler

Abstract

Nanocomposites based on poly-(St-co-BA-co-MMA) and organo-montmorillonite (OMMT) were synthesized through miniemulsion polymerization. OMMT was used as filler after modification with cetyltrimethylammonium bromide (CTAB) through ion exchange method. The results were characterized with x-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectrophotometer. Unmodified MMT showed a diffraction peak at 2θ = 7.2° with interlayer spacing of 12.78 Å, shifting to lower angle of 2θ = 4.7° with interlayer spacing increased to 22.31 Å formed pseudotrilayer or paraffin structure. FTIR confirmed the XRD results with the presence of new peaks on modified MMT, indicated the amine groups have inserted into MMT layers. Miniemulsion polymerization with OMMT level up to 8.0 wt% was performed well with less coagulum in the latex; scaling up to higher level of OMMT (>10 wt%) affected instability in polymerization system, created high amount of coagulum and increased the latex Broekfield Viscosity from 150 cPs to 528 cPs. Water vapor transmission rate (WVTR) of latex with 8.0 wt% OMMT level was compatible to LDPE and PET films but still unable to compete with OPP film.