Studies on the copolymerisation of <i>n</i>-alkyl itaconates with styrene

2523-2526The synthesis and characterization of n-hexyl itaconate (HI) and n-octyl itaconate (OI) monomers and their homopolymerisation and copolymerisation with styrene in bulk using azobisisobutyronitrile (AIBN) as an initiator have been reported. Copolymer composition has been determined from 1H-NMR by taking the ratio of intensities of signals due to -OCH2 protons of itaconates (δ =3.9 ppm) and aromatic protons of styrene (δ =6.8-7.2 ppm). The intensity of signal due to -OCH2 proton increases with increasing mole fraction of itaconate monomers in the feed. The reactivity ratios are found to be rl = 1.2 (styrene), r2 = 0.75 (HI) and rl = 1.38 (styrene), r2 = 0.62 (OI). All the samples have high moleculer weight, i.e., Mn in the range of 40 × 103 to 62 × 103 and Mw in the range of 43 × 103 to 113 × 103 with polydispersity index in the range of 1.64-1.85. Intrinsic viscosity [η] of the copolymers decreases with increasing amount of itaconate in the copolymers. Inspite of having very high molecular weight (77,000-78,000) the homopolymers (PHI, POI) have a very low value of [η] (4±0.5 ml/g). These low values of [η] may be due to the presence of long branches in itaconates showing comb type structure. Thermal studies of the copolymers show all the samples to be stable up to 300°C