Some physico-chemical properties of Homo-and Co-polymers from Mono-and Di-alkyl esters of Itaconic acid

Abstract

Polymers and copolymers of mono- and di-n-alkyl esters of itaconic acid, with side chain ler>,ths from one to twelve carbons have been prepared. The reactivity ratios of selected copolymer systems have been established. The thermo-mechanical behaviour of both homopolymers and copolymers has been studied. Torsional braid analysis and differential scanning calorimetry were employed to locate glass transition temperatures and sub-transition temperatures. As the length of the ester side chains in the poly(di-n-alkyl itaconates) changes from methyl through to decyl, the glass transitions were found to decrease to a minimum at heptyl and increase slightly thereafter. A second major transition was observed in poly(di-esters) when the side chains contain seven or more carbon atoms. This has been assigned to relaxation of the side chain prior to the onset of main chain relaxation. The thermal stability of the polymers was studied by both thermal volatalisation analysis and thermogravimetric analysis. The thermal behaviour of the di-ester polymers was found to be comparable with the corresponding polyacrylates while mono ester polymers were observed to undergo thermal modification, involving the formation of anhydride structures, at ^430K. Except for poly(monononyl itaconate) and polyCmonodecy] itaconate), glass transitions were not observable for the latter series. 11. Ionomers, based on copolymers of a mono- and a di-ester were prepared by neutralising the free carboxyl groups with sodium and caesium hydroxides. The mechanical behaviour of these was studied using linear viscoelastometry. This showed the ionomers to possess both increased mechanical and thermal stability when compared with parent copolymers. The morphology of the ionomers was investigated using electron microscopy. The results indicate the absence of ionic aggregation at low ion concentration, but the possible presence of aggregation at high ion concentration.