Poly(methyl methacrylate) Copolymers Containing Multiple, Pendent Plasticizing Groups

Lon J. Mathias, University of Southern Mississippi

Originally published in Journal of Polymer Science, Part A: Polymer Chemistry, Volume 48, Issue 11, 1 June 2010, Pages 2302-2310

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New ether dimer (ED-Eh) and diester (EHDE) derivatives of α-(hydroxymethyl)acrylate, each having two 2-ethylhexyl side chains, and an amine-linked di(2-ethylhexyl)acrylate (ALEh), having three 2-ethylhexyl side chains, were synthesized and (co)polymerized to evaluate the effects of differences in the structures of the monomers on final (co)polymer properties, particularly glass transition temperature, Tg. The free radical polymerizations of these monomers yielded high-molecular-weight polymers. Cyclopolymer formation of ED-Eh and AL-Eh was confirmed by 13C NMR analysis and the cyclization efficiencies were found to be very high (∼100%). Copolymers of ED-Eh, EHDE, and AL-Eh with methyl methacrylate (MMA) showed significant Tg decreases over poly(methyl methacrylate) (PMMA) due to 2-ethylhexyl side groups causing "internal" plasticization. Comparison of the Tg's of the copolymers of 2-ethylhexyl methacrylate, ED-Eh, EHDE, and AL-Eh with MMA revealed that the impacts of these monomers on depression of Tg's are Identical with respect to the total concentration of the pendent groups. This is consistent with an earlier study involving copolymers of monomers comprising one and two octadecyl side groups with MMA. That is, the magnitude of decrease in T g's was quantitatively related to the number of the 2-ethylhexyl pendent groups in the copolymers rather than their placement on the same or randomly incorporated repeat units. © 2010 Wiley Periodicals, Inc.