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Terpolymerization kinetics of N,N-dimethylaminoethyl methacrylate/alkyl methacrylate/styrene systems

Low conversion kinetics of terpolymerization of N, N-dimethylaminoethyl methacrylate (DMAEM) and dodecyl methacrylate (DDMA) with methyl methacrylate (MMA) or styrene (ST) was investigated. Reactions were performed isothermally at 70 oC, in toluene solutions, using 1-di(tert-butylperoxy)-3, 3, 5-trimethylcyclohexane as the initiator. Composition of synthesized terpolymers was determined by 1H-NMR and elemental analysis. The interdependence between terpolymer and monomer feed mixture composition was successfully described by Alfrey-Goldfinger terpolymerization equation, as well as the curves of unique and binary azeotropic compositions. In MMA-containing terpolymerization system, the wide pseudoazeotropic region with existence of true azeotropic point was observed and experimentally confirmed at the molar ratio for DMAEM / MMA / DDMA of 0.56 / 0.41 / 0.03. In the ST-containing terpolymerization system compositional heterogeneity was significant, more than 10 mol %. Required copolymerization reactivity ratios for binary pairs of monomers were determined by linear and nonlinear methods. The average values found for the system DMAEM (1) / MMA (2) / DDMA (3) were as follows: r12 = 0.83, r21 = 0.79 ; r13 = 0.79, r31 = 0.74 ; r23 = 1.11, r32 = 1.18 and for the system DMAEM (1) / ST (2) / DDMA (3): r12 = 0.45, r21 = 1.77 ; r13 = 0.79, r31 = 0.74 ; r23 = 2.19, r32 = 0.45. The content of low molar mass monomers MMA and ST in the reaction mixture has a notable influence on the overall polymerization rate values ; increasing the MMA or ST content in the monomer mixture caused a decrease in the initial reaction rates, Rp. Lower reaction rates were found in ST-containing terpolymerization system. The glass transition temperature of DMAEM / (MMA or ST) / DDMA terpolymers was determined by the DSC method. It was found that transition values are between those of the corresponding homopolymers and relative to their content. An increase in the MMA or ST contents and a decrease in the DDMA content in terpolymers results in an increase in their glass transition temperatures.

N, N-dimethylaminoethyl methacrylate ; dodecyl methacrylate ; styrene ; methyl methacrylate ; terpolymerization kinetics ; copolymerization reactivity ratios ; glass transition temperature

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