Effect of the conditions of synthesis of polymethyl-methacrylate on the heat of polymerization

Abstract The heats of polymerization of methymethacrylate in bulk and in various solvents have been determined by the joint use of the methods of calorimetry and ozonolysis and the structural features of the polymers obtained have been investigated by IR spectroscopy. It has been found that the heats of polymerization are higher in solution than in bulk and vary with the nature of the solvent. It has been shown that the excess heat evolution is caused both by specific interaction between the components of the solution and also by aggregation of the macromolecules through the linking of CO groups into stable associates. The splitting of the valency vibration band of the CO bond in the IR spectra of PMMA is evidence of the existence of associates of this type. It is incorrect to use the standard heat of polymerization of methylmethacrylate in bulk to study the kinetics of polymerization in solution and it is necessary to determine this quantity for each specific system.