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NMR study of the microstructure of methyl-n-hexadecyl itaconate with styrene copolymers

Abstract:

A series of copolymers of styrene with methyl-n-hexadecylitaconates using different compositions in the feed have been prepared in bulk via radical at 60°C with AIBN as initiator. In most of the cases the copolymers were obtained in good yields and the increase of one of the monomers in the feed mixture raises its amount in the copolymer and in some cases the copolymer composition is close to the feed ratio. The copolymers molecular structure was characterized by FTIR and a detailed study of NMR spectroscopy which included 1H, 13C and bidimentional experiments. The NMR studies indicate that the copolymers have a mainly random distribution of the monomeric units and the chemical shifts of the signals, especially the OCH3 and OCH2 are strongly influenced by the neighbor environment. 13C NMR chemical shifts were also analyzed by simulation studies using ab initio Gauge-Independent Atomic Orbital (GIAO) calculations; we observed a good correlation between the experimental and calculated values.