Copolymerization of styrene and methyl methacrylate in ternary oil-in-water microemulsions: Monomer reactivity ratios and microstructures by1H NMR and13C NMR

Abstract

The monomer reactivity ratios of styrene (rS) and methyl methacrylate (rM) copolymerization in ternary oil-in-water microemulsions were determined from the 1H NMR spectra. The obtained values of rS = 0.74 ± 0.09 and rM = 0.38 ± 0.04 are different from those determined by homogeneous polymerizations. The results are discussed in terms of the partitioning of monomers in the microemulsions and the copolymerization loci. Information about the microstructures of copolymers was derived from the analysis of the methoxyl region of the 1H NMR spectra and the α-methyl region as well as the aromatic C1 region of the 13C NMR spectra. The experimental results on the copolymer microstructures are in good agreement with the calculated values using the newly determined rS and rM. The glass transition temperatures (Tg) of the copolymers were found to decrease linearly with increasing mole fraction of styrene in the copolymers. © 1994 American Chemical Society.