Synthesis of Stimuli-Responsive Star-Like Copolymer H20-PNIPAm-r-PEGMA via the ATRP Copolymerization Technique and its Micellization in Aqueous Solution

A series of novel star-like copolymers H20-poly(N-isopropylacrylamide)-random-poly(poly(ethylene glycol) methyl ether methacrylate) (H20-PNIPAm-r-PEGMA), which could respond to both temperature and ionic strength stimuli in aqueous solution were synthesized by atom transfer radical polymerization. Stimuli-response of these copolymers in aqueous solution was characterized by dynamic laser scattering (DLS), 1H-NMR and turbidity. In aqueous solution, these star-like copolymers exhibited response to temperature and ionic strength with tunable low-critical solution temperature (LCST) from 32 to 100°C. The LCST values of copolymers increased with increasing PEGMA contents, while decreased with increasing ionic strength. An interesting phenomenon, which should be a unique character of star-like copolymer, was observed by the turbidity test of copolymer 1160. The addition of sodium chloride and increase of concentration can let copolymer 1160 behave normally, which was further confirmed by atomic force microscopy and DLS. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

[1]  Yi Yan Yang,et al.  Preparation and characterization of fast response macroporous poly(N-isopropylacrylamide) hydrogels , 2001 .

[2]  J. Fréchet,et al.  Dendrimers and Other Dendritic Polymers: Frechet/Dendrimers , 2001 .

[3]  Chi Wu,et al.  Study of the Core-Shell Nanoparticle Formed through the ``Coil-to-Globule'' Transition of Poly(N-isopropylacrylamide) Grafted with Poly(ethylene oxide) , 1997 .

[4]  Allan S Hoffman,et al.  Poly(N-isopropylacrylamide-co-propylacrylic acid) copolymers that respond sharply to temperature and pH. , 2006, Biomacromolecules.

[5]  Paschalis Alexandridis,et al.  Differential scanning calorimetry investigation of the effect of salts on aqueous solution properties of an amphiphilic block copolymer (poloxamer) , 1997 .

[6]  J. Zou,et al.  Synthesis and thermally responsive characteristics of dendritic poly(ether-amide) grafting with PNIPAAm and PEG , 2007 .

[7]  Jan Feijen,et al.  Thermosensitive Micelle-Forming Block Copolymers of Poly(ethylene glycol) and Poly(N-isopropylacrylamide) , 1997 .

[8]  Jan Feijen,et al.  Effect of comonomer hydrophilicity and ionization on the lower critical solution temperature of N-isopropylacrylamide copolymers , 1993 .

[9]  J. Baker,et al.  Regulation of in vitro gene expression using antisense oligonucleotides or antisense expression plasmids transfected using starburst PAMAM dendrimers. , 1996, Nucleic acids research.

[10]  Franz Hofmeister,et al.  Zur Lehre von der Wirkung der Salze , 1891, Archiv für experimentelle Pathologie und Pharmakologie.

[11]  E. Rizzardo,et al.  Molecular weight characterization of poly(N-isopropylacrylamide) prepared by living free-radical polymerization , 2000 .

[12]  K. Wynne,et al.  Co-Polyoxetanes with Alkylammonium and Fluorous or PEG-Like Side Chains : Soft Blocks for Surface Modifying Polyurethanes , 2007 .

[13]  Ashutosh Chilkoti,et al.  Control of protein–ligand recognition using a stimuli-responsive polymer , 1995, Nature.

[14]  Satoshi Koizumi,et al.  Thermosensitive Diblock Copolymer of Poly(N-isopropylacrylamide) and Poly(ethylene glycol) in Water: Polymer Preparation and Solution Behavior , 2005 .

[15]  R. Crooks,et al.  Homogeneous Hydrogenation Catalysis with Monodisperse, Dendrimer-Encapsulated Pd and Pt Nanoparticles. , 1999, Angewandte Chemie.

[16]  B. Chowdhry,et al.  Effect of Sodium Chloride upon Micellization and Phase Separation Transitions in Aqueous Solutions of Triblock Copolymers: A High-Sensitivity Differential Scanning Calorimetry Study , 1998 .

[17]  J. Zou,et al.  Encapsulation and controlled release of a hydrophobic drug using a novel nanoparticle-forming hyperbranched polyester. , 2005, Macromolecular bioscience.

[18]  D. M. Grove,et al.  Homogeneous catalysts based on silane dendrimers functionalized with arylnickel(II) complexes , 1994, Nature.

[19]  Hongwei Chen,et al.  Folding and Unfolding of Individual PNIPAM-g-PEO Copolymer Chains in Dilute Aqueous Solutions , 2005 .

[20]  Y. Osada,et al.  A polymer gel with electrically driven motility , 1992, Nature.

[21]  Raoul Kopelman,et al.  Dendrimers as Controlled Artificial Energy Antennae , 1997 .

[22]  Toyoichi Tanaka,et al.  Volume phase transition in a nonionic gel , 1984 .

[23]  Guy Van Assche,et al.  Influence of Macromolecular Architecture on the Thermal Response Rate of Amphiphilic Copolymers, Based on Poly(N-isopropylacrylamide) and Poly(oxyethylene), in Water , 2007 .

[24]  L. Dong,et al.  Thermally reversible hydrogels: III. Immobilization of enzymes for feedback reaction control , 1986 .

[25]  Jingjing Yan,et al.  Association and Aggregation Behavior of Poly(ethylene oxide)-b-Poly (N-isopropylacrylamide) in Aqueous Solution , 2008 .

[26]  Yingli An,et al.  Synthesis and micellization of thermo- and pH-responsive block copolymer of poly(N-isopropylacrylamide)-block-poly(4-vinylpyridine) , 2007 .

[27]  Takashi Miyata,et al.  A reversibly antigen-responsive hydrogel , 1999, Nature.

[28]  C. van Nostrum,et al.  The effect of the processing and formulation parameters on the size of nanoparticles based on block copolymers of poly(ethylene glycol) and poly(N-isopropylacrylamide) with and without hydrolytically sensitive groups. , 2004, Biomaterials.

[29]  J. Fréchet,et al.  Stimuli-responsive supramolecular assemblies of linear-dendritic copolymers. , 2004, Journal of the American Chemical Society.

[30]  K. Kono,et al.  Design of biocompatible dendrimers with environment sensitivity , 2003 .

[31]  Wei Zhang,et al.  Synthesis and self-assembly behaviors of three-armed amphiphilic block copolymers via RAFT polymerization , 2008 .