Synthesis of thermo-responsive polymer via radical (Co)polymerization of N, N-Dimethyl-α-(hydroxymethyl)acrylamide with N, N-diethylacrylamide

Abstract

α-Functionalized acrylamides have not been considered as an effective monomer design due to their poor polymerizability, although the analogues, α-functionalized acrylates, are attractive monomers of which polymers exhibit characteristic properties. In this article, we report the first example of radical polymerization of α-functionalized N, N-disubstituted acrylamide affording thermo-responsive hydrophilic polymers. N, N-dimethyl-α-(hydroxymethyl)acrylamide (DMαHAA) was (co)polymerized with N, N-diethylacrylamide (DEAA). Although the homopolymerization did not afford a polymeric product, the copolymerizations with various feed ratios yielded a series of the copolymers containing 0%-65% of DMαHAA units. The obtained copolymers exhibited a lower critical solution temperature (LCST) in water; the cloud points (Tcs) were linearly elevated as the contents of DMαHAA units from 32 to 64 °C, indicating that DMαHAA functioned as a more hydrophilic monomer than DEAA. The linear relationship between Tc and DMαHAA content suggests that the homopolymer, poly(DMαHAA), should have Tc at ca. 80 °C, although it is not available by direct radical homopolymerization.