Preparation and application of chiral recognizable thermosensitive polymers and hydrogels consisting of N ‐methacryloyl‐ s ‐phenylalanine methyl ester

Amphiphilic random copolymers, poly( R ‐HPMA‐co‐ S ‐PAM) and poly(HPMA‐co‐ S ‐PAM), were prepared by radical copolymerization of N ‐methacryloyl‐( S )‐phenylalanine methyl ester ( S ‐PAM) and N ‐[( R )‐2‐hydroxypropyl]methacrylamide ( R ‐HPMA) or N ‐(2‐hydroxypropyl)methacrylamide (HPMA) with various molar ratios of R ‐HPMA (or HPMA) (m) to S ‐PAM (n). Either aqueous solution of poly( R ‐HPMA‐co‐ S ‐PAM) with the molar ratio of m : n = 0.81 : 0.19 or poly(HPMA‐co‐ S ‐PAM) with the molar ratio of m : n = 0.79 : 0.21 exhibited the lower critical solution temperature (LCST) at 16°C. The LCST in the presence of ( S )‐(−)‐phenylalanine ( S ‐Phe) shifted from 16 to 20°C and 18°C for poly( R ‐HPMA‐co‐ S ‐PAM) and poly(HPMA‐co‐ S ‐PAM), respectively, whereas the LCST did not shift in the presence of ( R )‐(+)‐phenylalanine ( R ‐Phe). Thermosensitive Gel( R ‐HPMA‐co‐ S ‐PAM) and Gel(HPMA‐co‐ S ‐PAM) were also prepared from radical copolymerization of S ‐PAM and R ‐HPMA or HPMA in the presence of N,N ′‐ethylenebisacrylamide (EBAAm) as a crosslinker. When the gels shrunk at 40°C, the release of dansyl‐( R )‐phenylalanine (Dans‐ R ‐Phe) from the gel in which loaded Dans‐ R ‐Phe occurred was more easily done than that of Dans‐ S ‐Phe from the gel that loaded Dans‐ S ‐Phe. Thus, these thermosensitive copolymers and gels were found to exhibit chiral recognition for phenylalanine derivatives. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 228–236, 2001