The polymerisation kinetics of lower dialkyl itaconates

The free radical polymerisation kinetics of diethyl- (DEI), dipropyl- (DnPI), dibutyl- (DnBI), and dihexyl itaconate (DHI) in the bulk were studied in the temperature range from 50 to 70°C. The concentration of the initiator, 2,2′-azoisobutyronitrile (AIBN), was varied between 0.02 and 0.085 mol/dm³. The rate of polymerisation (R_p), degree of polymerisation (DP), overall polymerization rate constant (K), the ratio of the propagation and termination rate constants (k_p/k_t^1/2), as well as the chain transfer constant to monomer (C_M) were determined. The values of R_p, K, and k_p/k_t^1/2 of the investigated monomers all increase with increasing size of the alkyl group in the ester substituent, whereas C_M decreases when going from the dimethyl to the dihexyl ester. The values of C_M are larger than the corresponding values for the alkyl esters of methacrylic acid.