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

Huseyin Tas, University of Southern Mississippi
Lon J. Mathias, University of Southern Mississippi

Abstract

New ether dimer (ED-Eh) and diester (EHDE) derivatives of alpha-(hydroxymethyl)acrylate, each having two 2-ethylhexyl side chains, and an amine-linked di(2-ethylhexyl)acrylate (AL-Eh), 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, T(g). The free radical polymerizations of these monomers yielded high-molecular-weight polymers. Cyclopolymer formation of ED-Eh and AL-Eh was confirmed by (13)C NMR analysis and the cyclization efficiencies were found to be very high (similar to 100%). Copolymers of ED-Eh, EHDE, and AL-Eh with methyl methacrylate (MMA) showed significant T(g) decreases over poly(methyl methacrylate) (PMMA) due to 2-ethylhexyl side groups causing "internal" plasticization. Comparison of the T(g)'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 T(g)'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. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2302-2310, 2010