Lower critical solution temperatures of thermo‐responsive poly(N‐isopropylacrylamide) copolymers with racemate or single enantiomer groups

BACKGROUND: Thermo-responsive copolymers with racemate or single enantiomer groups are attracting increasing attention due to their fascinating functional properties and potential applications. However, there is a lack of systematic information about the lower critical solution temperature (LCST) of poly(N-isopropylacrylamide)-based thermo-responsive chiral recognition systems. In this study, a series of thermo-responsive chiral recognition copolymers, poly[(N-isopropylacrylamide)-co-(N-(S)-sec-butylacrylamide)] (PN-S-B) and poly[(N-isopropylacrylamide)-co-(N-(R,S)-sec-butylacrylamide)] (PN-R,S-B), with different molar compositions, were prepared. The effects of heating and cooling processes, optical activity and amount of chiral recognition groups in the copolymers on the LCSTs of the prepared copolymers were systematically studied. RESULTS: LCST hysteresis phenomena are found in the phase transition processes of PN-S-B and PN-R,S-B copolymers in a heating and cooling cycle. The LCSTs of PN-S-B and PN-R,S-B during the heating process are higher than those during the cooling process. With similar molar ratios of N-isopropylacrylamide groups in the copolymers, the LCST of the copolymer containing a single enantiomer (PN-S-B) is lower than that of the copolymer containing racemate (PN-R,S-B) due to the steric structural difference. The LCSTs of PN-R,S-B copolymers are in inverse proportion to the molar contents of the hydrophobic R,S-B moieties in these copolymers. CONCLUSION: The results provide valuable guidance for designing and fabricating thermo-responsive chiral recognition systems with desired LCSTs. Copyright © 2008 Society of Chemical Industry

[1]  Yuanli Cai,et al.  Facile Synthesis and Photo-Tunable Properties of a Photosensitive Polymer Whose Chromophores Bound with pH-Labile Cyclic Acetal Linkages , 2008 .

[2]  P. Schwille,et al.  Supported lipid bilayers on spacious and pH-responsive polymer cushions with varied hydrophilicity. , 2008, The journal of physical chemistry. B.

[3]  Liang-Yin Chu,et al.  A Thermoresponsive Membrane for Chiral Resolution , 2008 .

[4]  Liang-Yin Chu,et al.  Molecular‐Recognition‐Induced Phase Transitions of Two Thermo‐Responsive Polymers with Pendent β‐Cyclodextrin Groups , 2008 .

[5]  Liang-Yin Chu,et al.  A Smart Polymer with Ion-Induced Negative Shift of the Lower Critical Solution Temperature for Phase Transition , 2008 .

[6]  Yasuhiro Shiraishi,et al.  Temperature-driven on/off fluorescent indicator of pH window : an anthracene-conjugated thermoresponsive polymer , 2007 .

[7]  Y. Lee,et al.  Synthesis and Characterization of a Novel Thermo-Sensitive Copolymer of N-Isopropylacrylamide and Dibenzo-18-crown-6-diacrylamide , 2006 .

[8]  R. Sebra,et al.  Synthesis and photografting of highly pH-responsive polymer chains , 2006 .

[9]  Xiaoqing Zhang,et al.  pH effect on the mechanical performance and phase mobility of thermally processed wheat gluten-based natural polymer materials. , 2006, Biomacromolecules.

[10]  H. Lee,et al.  Surface-Imprinted, Thermosensitive, Core-Shell Nanosphere for Molecular Recognition , 2006 .

[11]  T. Yamaguchi,et al.  An Autonomous Phase Transition−Complexation/Decomplexation Polymer System with a Molecular Recognition Property , 2006 .

[12]  Chi Wu,et al.  LLS and FTIR Studies on the Hysteresis in Association and Dissociation of Poly(N-isopropylacrylamide) Chains in Water , 2006 .

[13]  Liang-Yin Chu,et al.  Positively Thermo‐Sensitive Monodisperse Core–Shell Microspheres , 2003 .

[14]  A. Dobashi,et al.  Enantiomeric separation using temperature-responsive chiral polymers composed of L-valine diamide derivatives in aqueous liquid chromatography. , 2003, Journal of chromatography. A.

[15]  H. Choi,et al.  Physical and electroresponsive characteristics of the intercalated styrene-acrylonitrile copolymer/clay nanocomposite under applied electric fields , 2003 .

[16]  A. Bobrovsky,et al.  Photo-optical behaviour of a photosensitive chiral nematic copolymer and mixtures containing non-chiral photoactive azobenzene groups , 2003 .

[17]  Bo Mattiasson,et al.  Photosensitive copolymer of N-isopropylacrylamide and methacryloyl derivative of spyrobenzopyran , 2002 .

[18]  L. Billon,et al.  Hydrophobically associating polyacrylamides and their partially hydrolyzed derivatives prepared by post-modification. 1. Synthesis and characterization , 2002 .

[19]  A. Knoll,et al.  Large Scale Domain Alignment of a Block Copolymer from Solution Using Electric Fields , 2002 .

[20]  K. Sugiyama,et al.  Preparation and application of chiral recognizable thermosensitive polymers and hydrogels consisting of N-methacryloyl-s-phenylalanine methyl ester , 2001 .

[21]  A. Bobrovsky,et al.  Photosensitive cholesteric polymers with azobenzene-containing chiral groups and mixtures of cholesteric copolymer with chiral-photochromic dopants , 2001 .

[22]  K. Horie,et al.  Deuterium Isotope Effect on the Phase Separation of Zipper‐Type Hydrogen‐Bonding Inter‐Polymer Complexes in Solution , 2001 .

[23]  Minghong G. Wu,et al.  Preparation of interpenetrating polymer networks by two times grafting of monomers onto preirradiated polypropylene film , 2000 .

[24]  B. Vincent,et al.  A comparison of the swelling behaviour of copolymer and interpenetrating network microgel particles , 2000 .

[25]  T. Okano,et al.  Thermosensitive Phase-Separation Behavior of Poly(acrylic acid)-graft-poly(N,N-dimethylacrylamide) Aqueous Solution , 2000 .

[26]  G. Pereira,et al.  Diblock Copolymer Melts in Electric Fields: The Transition from Parallel to Perpendicular Alignment Using a Capacitor Analogy , 1999 .

[27]  Fang Zeng,et al.  Inverse Molecular Weight Dependence of Cloud Points for Aqueous Poly(N-isopropylacrylamide) Solutions , 1999 .

[28]  N. Ogata,et al.  Phase-transition changes of poly(N-(S-sec-butylacrylamide-co-N-isopropylacrylamide) in response to amino acids and its chiral recognition , 1998 .

[29]  Chi Wu,et al.  Globule-to-Coil Transition of a Single Homopolymer Chain in Solution , 1998 .

[30]  H. G. Schild.  Poly(N-isopropylacrylamide): experiment, theory and application , 1992 .

[31]  T. Okano,et al.  Drug Release OFF Behavior and Deswelling Kinetics of Thermo-Responsive IPNs Composed of Poly(acrylamide-co-butyl methacrylate) and Poly(acrylic acid) , 1991 .

[32]  K. Kubota,et al.  Phase transition of aqueous solutions of poly(N-isopropylacrylamide) and poly(N-isopropylmethacrylamide) , 1989 .