Factorial design of nanosized polyisoprene synthesis via differential microemulsion polymerization

The synthesis of nanosized polyisoprene latex was carried out by differential microemulsion polymerization using 2, 2'-Azoisobutyronitrile (AIBN) initiator system under various reaction conditions. A 2(V)(5-1) fractional factorial experimental design was applied to study the effects of reaction variables: amount of initiator and surfactant, monomer-to-water ratio, reaction temperature, and stirring speed on rubber particle size and monomer conversion. The analysis of the results from the design showed the main effects on the observed response and the amount of initiator, reaction temperature and stirring speed in the range of the test had significant effects on polyisoprene particle size. The significant effects on monomer conversion were reaction temperature, stirring speed, and interaction between reaction temperature and stirring speed in the range of the test. The optimum conditions gave highest monomer conversion of 90% and average particle size of polyisoprene of 27 nm. The nanosized polyisoprene was also characterized by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Copyright (C) 2009 John Wiley & Sons, Ltd.