Synthesis of optically active macroporous poly(N-isopropylacrylamide) hydrogels with helical poly(N-propargylamide) for chiral recognition of amino acids

Optically active macroporous poly(N-isopropylacrylamide) (PNIPAM) hydrogels were synthesized via free radical copolymerization of NIPAM, helical macromonomer, and cross-linker N,N′-methylenebisacrylamide. The helical macromonomer not only contained catechol groups but also vinyl groups in side chains. Polyethylene glycols were used as pore-forming agent to give rise to macroporous structures in the optically active hydrogels. The hydrogels were characterized by FT-IR, SEM, DSC, swelling ratio and circular dichroism spectra analyses and exhibited the expected optical activity and macroporous architectures. The chiral resolution tests demonstrated the preferential adsorption of the hydrogels towards d-tryptophan and d-phenylalanine in the corresponding two amino acid enantiomers.