Abstract
This paper describes that the optically active moieties, ((S) -sec-butylacrylamide (BAAm)), in N-isopropylacrylamide (IPAAm) copolymer chains affected the phase transition behavior and resulted in lower critical solution temperature (LCST) changes responding to foreign tryptophan (Trp). Copolymerization of (S) -sec-BAAm and IPAAm were carried out in DMF at 70°C for 25 h using AIBN. The copolymer was water-soluble and showed the characteristic LCST near 27°C. LCSTs of PIPAAm chains are affected by hydrophobic or hydrophilic nature of comonomers. Since sec-BAAm is insoluble in water, the component exhibited hydrophobic property. Therefore, poly ((S) -sec-BAAm-co-IPAAm) showed lower LCST as compared with that of PIPAAm. The LCSTs of the copolymer in the presence of L-Trp weve higher than those in the absence of the amino acid. It was understood that the optically active moieties in the copolymer stereospecifically interact with L-Trp, relatively enhancing hydrophilic property of the polymer chains. The copolymer increased the LCSTs in response to increasing L-Trp concentration. Hydrogels consisting of these comonomers will exhibit reversible swelling/ deswelling behavior in response to L-amino acids such as L-Trp. The polymers with the optically active moieties demonstrate the chiral discrimination to L-amino acids and are also good candidates to perform chiral separation.
