Following Sharpless' visionary characterization of several idealized reactions as click reactions, the materials science and synthetic chemistry communities have pursued numerous routes toward the identification and implementation of these click reactions. Herein, we review the radical-mediated thiol-ene reaction as one such click reaction. This reaction has all the desirable features of a click reaction, being highly efficient, simple to execute with no side products and proceeding rapidly to high yield. Further, the thiol-ene reaction is most frequently photoinitiated, particularly for photopolymerizations resulting in highly uniform polymer networks, promoting unique capabilities related to spatial and temporal control of the click reaction. The reaction mechanism and its implementation in various synthetic methodologies, biofunctionalization, surface and polymer modification, and polymerization are all reviewed.

Thiol–Ene Click Chemistry

This paper provides a third update to the review of reversible deactivation radical polymerization (RDRP) achieved with thiocarbonylthio compounds (ZC(=S)SR) by a mechanism of reversible addition-fragmentation chain transfer (RAFT) that was published in June 2005 (Aust. J. Chem. 2005, 58, 379). The first update was published in November 2006 (Aust. J. Chem. 2006, 59, 669) and the second in December 2009 (Aust. J. Chem. 2009, 62, 1402). This review cites over 700 publications that appeared during the period mid 2009 to early 2012 covering various aspects of RAFT polymerization which include reagent synthesis and properties, kinetics and mechanism of polymerization, novel polymer syntheses, and a diverse range of applications. This period has witnessed further significant developments, particularly in the areas of novel RAFT agents, techniques for end-group transformation, the production of micro/nanoparticles and modified surfaces, and biopolymer conjugates both for therapeutic and diagnostic applications.

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Living Radical Polymerization by the RAFT Process - A Second Update

Thiol-ene “click” reactions and recent applications in polymer and materials synthesis

Radical addition-fragmentation chemistry in polymer synthesis

This review concerns the applications of some polysaccharides in the domain of biomaterials and bioactive polymers. Natural polysaccharides from different sources have been studied for a long time, and their main properties are summarized in this paper; some of their derivatives obtained by chemical modification are also described. The main polysaccharides currently used in the biomedical and pharmaceutical domains are chitin and its derivative chitosan, hyaluronan and alginates. Alginates are well known for their property of forming a physical gel in the presence of divalent counterions (Ca, Ba, Sr) whereas carrageenans form a thermoreversible gel; these seaweed polysaccharides are mainly used to encapsulate different materials (cells, bacteria, fungi). Other promising systems are the electrostatic complexes formed when an anionic polysaccharide is mixed with a cationic polysaccharide (e.g. alginate/chitosan or hyaluronan/chitosan). An important development of the applications of polysaccharides can be predicted for the next few years in relation to their intrinsic properties such as biocompatibility and biodegradability in the human body for some of them; they are also renewable and have interesting physical properties (film-forming, gelling and thickening properties). In addition, they are easily processed in different forms such as beads, films, capsules and fibres. Copyright © 2007 Society of Chemical Industry

Main properties and current applications of some polysaccharides as biomaterials

Department of Chemistry and Faculty of Pharmacy,UniVersity of Montreal, CP6128 Succursale Centre Ville,Montreal, QC, Canada H3C 3J7, and Department ofPolymer Chemistry, Graduate School of Engineering, KyotoUniVersity, Katsura, Kyoto 615-8510, JapanReceiVed June 19, 2007ReVised Manuscript ReceiVed August 15, 2007The thermosensitivity of aqueous polymer solutions is thedriving force at work in various soft “intelligent” devices usedin biotechnology and nanotechnology.

Temperature-Induced Phase Transition of Well-Defined Cyclic Poly(N-isopropylacrylamide)s in Aqueous Solution

Summary: The trithiocarbonate end groups of polymers prepared by RAFT polymerization are converted into colorless and stable thioethers in a one-pot process that combines aminolysis of the trithiocarbonate functions and Michael addition of the resulting thiols to α, β-unsaturated carbonyl derivatives. This post polymerization procedure, which is carried out under mild conditions to near quantitative conversion, is described in the case of a telechelic poly(N-isopropylacrylamide) sample bearing isobutylsulfanylthiocarbonylsulfanyl end groups. The chemical composition, purity, and molar masses of the modified polymers are assessed by GPC, 1H NMR spectroscopy and UV-vis spectroscopy, which together demonstrate the efficiency of the method and confirm that the molecular weight and polydispersity of the precursor RAFT polymer are not affected by the treatment.

The facile, one pot synthesis combines the reactions of trithiocarbonate aminolysis and Michael addition of a thiol to an α, β-unsaturated ester to transform the labile, colored thiocarbonylthio moiety into a stable, colorless thioether.

Facile and Efficient One-Pot Transformation of RAFT Polymer End Groups via a Mild Aminolysis/Michael Addition Sequence

Aqueous solutions of amphiphilic polymers often undergo a heat-induced phase separation, which is known as the lower critical solution temperature (LCST) phase transition. In the case of aqueous poly(2-isopropyl-2-oxazoline) (PIPOZ) solutions, the phase separation is followed, upon prolonged heat treatment, by an irreversible crystallization of the polymer. Optical microscopy observation of a PIPOZ solution (60 g L–1) in water revealed that liquid–liquid phase separation of the aqueous PIPOZ solution occurs at the cloud point (Tc) and that PIPOZ crystallizes in the polymer-rich liquid phase upon prolonged heating of the mixture at a temperature T > Tc. Vibrational spectroscopy combined with molecular orbital (MO) calculations and spectral measurements with model compounds were employed to monitor water/polymer interactions and changes in polymer conformation during the LCST-type phase separation. The thermally induced spectral variations suggest that the dehydration of the PIPOZ amide functions occurs gra...

Dissecting the Mechanism of the Heat-Induced Phase Separation and Crystallization of Poly(2-isopropyl-2-oxazoline) in Water through Vibrational Spectroscopy and Molecular Orbital Calculations

Poly(N-isopropylacrylamide)s (PNIPAMs) with cholesteryl or pyrenyl moieties at each chain end (CH-PNIPAMs or Py-PNIPAMs) were prepared via end-group modification of α,ω-dimercapto poly(N-isopropylacrylamides), ranging in molecular weight from ∼ 7000 to 45,000 g mol−1 with a polydispersity index of 1.10 or lower. The telechelic thiol functionalized PNIPAMs were obtained by aminolysis of α,ω-di(isobutylthiocarbonylthio)-poly(N-isopropylacrylamide)s (iBu-PNIPAMs) obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide in the presence of the difunctional chain transfer agent, diethylene glycol di(2-(1-isobutyl)sulfanylthiocarbonylsulfanyl-2-methyl propionate) (DEGDIM). The self-assembly of the polymers in water was assessed by fluorescence spectroscopy, using the intrinsic emission of Py-PNIPAM or the emission of pyrene added as a probe in aqueous solutions of CH-PNIPAM. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 314–326, 2008

An efficient synthesis of telechelic poly (N‐isopropylacrylamides) and its application to the preparation of α,ω‐dicholesteryl and α,ω‐dipyrenyl polymers

Xing-Ping Qiu

Papers

Temperature-Induced Phase Transition of Well-Defined Cyclic Poly(N-isopropylacrylamide)s in Aqueous Solution

Facile and Efficient One-Pot Transformation of RAFT Polymer End Groups via a Mild Aminolysis/Michael Addition Sequence

Dissecting the Mechanism of the Heat-Induced Phase Separation and Crystallization of Poly(2-isopropyl-2-oxazoline) in Water through Vibrational Spectroscopy and Molecular Orbital Calculations

An efficient synthesis of telechelic poly (N‐isopropylacrylamides) and its application to the preparation of α,ω‐dicholesteryl and α,ω‐dipyrenyl polymers

Hydration and Dynamic Behavior of a Cyclic Poly(N-isopropylacrylamide) in Aqueous Solution: Effects of the Polymer Chain Topology