Novel temperature-responsive functional polymers based on poly(N-(2-hydroxy-tert-butyl) acrylamide)

A type of bifunctional responsive polymer, poly(N-(2-hydroxyl-tert-butyl) acrylamide) (PHTBAM), having both reactivity and thermosensitivity was synthesized. Such polymer can be considered as a modified poly(N-isopropylacrylamide) (PNIPAM) by introducing hydroxymethyl group at α-position, which possesses responsive behavior similar to PNIPAM, and less dependence of external condition. Moreover, thermal phase transition of this polymer is completely reversible without any hysteresis. LCST of PHTBAM occurs around 23 °C, which can be modulated by copolymerization with more hydrophilic comonomer such as N-hydroxyethylacrylamide (HEAM). The LCST of the P(HTBAM-co-HEAM) copolymer can be adjusted over a wide range by increasing HEAM content up to higher lever, due to the structural similarity between HTBAM and HEAM units without destroying the PNIPAM–type main chain and loss of the response sensibility. In addition, the hydroxyl functional groups at side chain of PHTBAM provide a capability of further chemical modification for a variety of applications in material science and biotechnology.