Structure/Glass Transition Temperature Relationship of PVAc-b-poly(MA-co-MMA) Terpolymers with Theoretical and Topological Methods

The glass transition temperature of several PVAc(1)-b-poly(MA-co-MMA)(2) terpolymers with different fractions of methyl acrylate (MA) and methylmethacrylate (MMA) repeating units in random copolymer (block 2) werecalculated with Barton, Kwei and topological equations. The calculation was on thebasis of the correlation between the fraction of repeating units in random copolymersand theoretical equations and linear correlation of topological index of VAc, MA andMMA atomic structures in topological equations. The experimental values of theglass transition temperature of block 2 show a positive deviation from linearity inboth Barton and Kwei theoretically calculated values. Therefore, agreement betweenthe theoretical and experimental values were reached with summation of the effectsof sequence distributions in random copolymer (R, calculated with 1H NMR and statisticalmethods) to the linear theoretical data in Barton equation and the effect ofinteractions between the copolymer chains in Kwei equation (q = 14.9). The glasstransition temperature of 308 K was calculated for PVAc block with topologicalequation and it was near to the experimental value (310 K). Furthermore, the calculatedglass transition temperatures of the block 2 with linear method were considerablyclose to the experimentally obtained data and increased with mole fraction ofMMA in random copolymer.