Studies on the copolymerization of cyclic ketene acetals with styrene

Abstract

548-557   The paper describes the synthesis, characterization and copolymerization behaviour of 2-ethylidene-4-methyl-1, 3-dioxolane (A)/2-ethylidene-4 ethyl-1,3-dioxolane (B)/2-ethylidene-1,3-dioxepane (C)/2-ethylidene-1,3-dioxane (D) monomers with styrene. Homopolymerization and copolymerization of these monomers with styrene was carried out in bulk using free radical initiator. Structural characterization was done using FTIR and 1H-NMR spectroscopy. 1H NMR and FTIR spectroscopy was also used for the calculation of percentage ring opening and copolymer composition. The ring opening in case of ethylidene monomers having seven membered ring was maximum and minimum in case of ethylidene monomers having five membered ring.    Thermal characterization was done using differential scanning calorimetry and thermogravimetry in nitrogen atmosphere. Homopolymers of monomers A, C and D had Tg values of 50,-60 and -62oC respectively. Tg of the copolymers decreased with increasing amounts of cyclic ketene acetal monomers in the copolymers. All the homopolymers and copolymers were stable upto 350°C. Biodegradability of the polymers was also evaluated using the enzyme lipase. Incorporation of 0.2 mole fraction of these cyclic ketene acetals in polystyrene backbone improves its biodegradability