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.

/pdf/living-radical-polymerization-by-the-raft-process-a-second-3rre2ur7xt.pdf

Living Radical Polymerization by the RAFT Process - A Second Update

Dingcai Wu,*,† Fei Xu,† Bin Sun,† Ruowen Fu,† Hongkun He,‡ and Krzysztof Matyjaszewski*,‡ †Materials Science Institute, Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275, People's Republic of China ‡Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, United States

Design and Preparation of Porous Polymers

Interest in thermoresponsive polymers has steadily grown over many decades, and a great deal of work has been dedicated to developing temperature sensitive macromolecules that can be crafted into new smart materials. However, the overwhelming majority of previously reported temperature-responsive polymers are based on poly(N-isopropylacrylamide) (PNIPAM), despite the fact that a wide range of other thermoresponsive polymers have demonstrated similar promise for the preparation of adaptive materials. Herein, we aim to highlight recent results that involve thermoresponsive systems that have not yet been as fully considered. Many of these (co)polymers represent clear opportunities for advancements in emerging biomedical and materials fields due to their increased biocompatibility and tuneable response. By highlighting recent examples of newly developed thermoresponsive polymer systems, we hope to promote the development of new generations of smart materials.

New directions in thermoresponsive polymers.

A living radical polymerization (LRP) is a free radical polymerization that aims at displaying living character, (i.e., does not terminate or transfer and is able to continue polymerization once the initial feed is exhausted by addition of more monomer). However, termination reactions are inherent to a radical process, and modern LRP techniques seek to minimize such reactions, therefore providing control over the molecular weight and the molecular weight distribution of a polymeric material. In addition, the better LRP techniques incorporate many of the desirable features of traditional free radical polymerization, such as compatibility with a wide range of monomers, tolerance of many functionalities, and facile reaction conditions. The control of molecular weight and molecular weight distribution has enabled access to complex architectures and site specific functionality that were previously impossible to achieve via traditional free radical polymerizations. These LRPs are classified in three different subgroups: (1) stable free-radical polymerization such as nitroxide mediated polymerization (NMP),1,2 (2) degenerative transfer polymerization, such as iodine transfer polymerization (ITP and RITP),3,4 single electron transfer-degenerative transfer living radical polymerization(SET-DTLRP),5,6reversibleaddition-fragmentation chain transfer (RAFT),7,8 and macromolecular design via the interchange of xanthates (MADIX)9,10 polymerization, and (3) metal mediated catalyzed polymerization, such as atom transfer radical polymerization (ATRP),11-14 single electron transfer-living radical polymerization (SET-LRP),15 and organotellurium mediated living radical polymrization16-19 Among the existing LRP techniques, RAFT and MADIX are probably the most versatile processes, as they are tolerant * E-mail: T.P.D., T.Davis@UNSW.edu.au; S.P., S.Perrier@ chem.usyd.edu.au. † Centre for Advanced Macromolecular Design (CAMD), School of Chemical Sciences & Engineering, UNSW. ‡ Centre for Advanced Macromolecular Design (CAMD), School of Biotechnology & Biomolecular Sciences, UNSW. § The University of Sydney. Chem. Rev. 2009, 109, 5402–5436 5402

Bioapplications of RAFT polymerization.

https://www.pcr.ugent.be/Publications/artikelsPCR/Progress%20in%20polymer%20science/TalhaGokmen2011.pdf

Porous Polymer Particles - A Comprehensive Guide to Synthesis, Characterization, Functionalization and Applications

In recent years enzymes have found widespread use in areas as diverse as chemical synthesis, decontamination of waste streams, and biosensors. For ease of application and for stabilization purposes, enzymes are often immobilized on solid supports. These supports can include inorganic substrates such as silicon or glass, as well as organic materials such as polymers or hydrogels. In current industrial processes, enzymes are often simply adsorbed onto the material. Although this is a cost-effective method for supporting enzymes, these biocatalytic materials often suffer from decreased activity after prolonged usage because of the leakage of adsorbed enzymes during catalysis and recycling. Furthermore, since there is a lack of control over the enzyme positioning, only a fraction of the enzyme is in contact with the environment and therefore used effectively. In more sophisticated applications, such as sensors and analytical devices, covalent immobilization is achieved using carefully designed anchors and surface modification. These multistep procedures lead to welldefined systems, but costs are raised considerably and these methods are difficult to extend to large-scale applications. In this article we describe a simple and effective strategy for immobilizing enzymes covalently onto a solid porous support, and ascertain that a large fraction of the enzyme is available for catalysis. To achieve this, a support with a high surface to volume ratio is employed, namely a polymerized high internal phase emulsion (polyHIPE). N-Hydroxysuccinimide esters are introduced into this highly porous monolithic support for covalent coupling with the lysine residues present in proteins. When the activity of the well-known lipase Candida antarctica Lipase B (CAL-B) immobilized on polyHIPE was compared with the commercially available standard, Novozyme 435, a remarkable increase in both activity and stability was observed. PolyHIPEs are highly porous polymers obtained by polymerizing the continuous phase of a HIPE. The emulsion must have a droplet volume fraction of at least 0.74, and can exceed 0.99. The stability of this emulsion is mainly dependent on the nature of the surfactant, which should be soluble only in the continuous phase. PolyHIPEs have a well-defined open cellular morphology, with interconnecting holes (windows) between voids resulting from the continuous phase shrinkage during polymerization (see Fig. 1). Their unique morphology differentiates them from other porous polymers (e.g. gasblown foams), and yields excellent flow-through properties. Since the development of polyHIPEs in the 1980s, numerous applications have been developed, such as solid-phase peptide synthesis supports, catalyst supports, superabsorbents, ion-exchange resins, monolithic supports for cells, and membrane filters. However, the use of polyHIPEs as covalently immobilized enzyme supports for biocatalysis has not yet been reported. C O M M U N IC A TI O N S

Covalent enzyme immobilization onto photopolymerized highly porous monoliths

Elastin-based side-chain polymers (EBPs) were prepared by the polymerization of a methacrylate derivative of the pentapeptide valine−proline−glycine−valine−glycine (VPGVG) using reversible addition−fragmentation chain transfer (RAFT) polymerization. The polymerizations proceeded in a controlled manner, yielding polymers with a narrow molecular weight distribution (polydispersity indices 1.03−1.23) and molecular weights in good agreement with those predicted from the initial monomer:initiator ratio for the conversion obtained. The dithioester end groups of the resulting polymers were removed by reaction with azo initiator-derived radicals. The lower critical solution temperature (LCST) behavior of the series of EBPs so obtained was investigated in solutions of varying pH (1.5−5.1) and polymer concentration (0.11−0.97 mg/mL) and for polymers of different degrees of polymerization (29−88 repeating units). These EBPs behaved similarly to linear polypeptides, known as elastin-like peptides (ELPs); the transiti...

Alex Duréault

Papers

Covalent enzyme immobilization onto photopolymerized highly porous monoliths

Elastin-Based Side-Chain Polymers: Improved Synthesis via RAFT and Stimulus Responsive Behavior

Smart assembly of hybrid biolpolymers: a new enzyme immobilization tecnique