Polymer Chemistry Blog

The preparation of functional α,ω-dienes via thiol-Michael chemistry including synthesis, oxidative protection, acyclic diene metathesis (ADMET) polymerization and radical thiol–ene modification has been reported by van Hensbergen et al.

The synthesis of the novel α,ω-diene 2-(undec-10-en-1-yl)tridec-12-en-1-yl acrylate is described. Thiol-Michael coupling of this substrate followed by chemoselective oxidation of the thioether moiety with triazotriphosphorine tetrachloride (TAPC) furnished a suite of functional and symmetrical ADMET-active monomers in a quick and convenient manner. Polymerization of these adducts with Grubbs 1^st generation catalyst (RuCl₂(PCy₃)₂CHPh) was demonstrated to high conversion, and quantitative radical initiated thiol–ene modification of the backbone CC bonds was performed to impart additional functionality to each ADMET polymer. These reactions highlight the compatibility of thiol-based click chemistries for the preparation and post-modification of functional ADMET materials.

Remzi Becer is a web-writer and advisory board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information.

The synthesis and characterization of conducting polymers containing polypeptide and ferrocene side chains as ethanol biosensors has been reported by Yagci and Toppare et al.

This paper describes a novel approach for the fabrication of a biosensor from a conducting polymer bearing polypeptide segments and ferrocene moieties. The approach involves the electrochemical copolymerization of the electroactive polypeptide macromonomer and independently prepared ferrocene imidazole derivative of dithiophene, on the electrode surface. The polypeptide macromonomer was synthesized by the simultaneous formation of N-carboxyanhydride (NCA) and ring opening polymerization of N-Boc-L-lysine (α-amino acid of the corresponding NCA) using an amino functional bis-EDOT derivative (BEDOA-6) as an initiator. Alcohol oxidase was then covalently immobilized onto the copolymer coated electrode using glutaraldehyde as the crosslinking agent. The intermediates and final conducting copolymer before and after enzyme immobilization were fully characterized by FT-IR, ¹H-NMR, GPC, cyclic voltammetry, SEM and EIS analyses. The newly designed biosensor which combined the advantages of each component was tested as an ethanol sensing system offering fast response time (9 s), wide linear range (0.17 mM and 4.25 mM) and low detection limit (0.28 mM) with a high sensitivity (12.52 μA mM⁻¹ cm⁻²). Kinetic parameters K^app_M and I_max were 2.67 mM and 2.98 μA, respectively. The capability of the biosensor in determining ethanol content in alcoholic beverages was also demonstrated.

The synthesis of supramolecular polymers using supramonomers have been reported by Zhang et al.

The paper of the week describes a new method of fabricating supramolecular polymers through supramolecular polymerization of supramonomers. To mix building blocks of Phe-Gly-Gly linked with an azobenzene group and cucurbit[8]uril (CB[8]) in a molar ratio of 2:1 in aqueous solutions, supramonomers were obtained by host–guest interaction between tripeptide and CB[8]. Then supramolecular polymers were formed spontaneously by mixing the supramonomers with bis-β-cyclodextrins in a molar ratio of 1:1 in an aqueous solution through noncovalent host–guest complexation of the azobenzene group and β-cyclodextrin. Considering that various noncovalent interactions can be used to drive the formation of supramonomers and the supramolecular polymerization of the supramonomers, this study can enrich the methodology of fabricating supramolecular polymers.

Supramolecular polymerization of supramonomers: a way for fabricating supramolecular polymers by Qiao Song, Fei Li, Xinxin Tan, Liulin Yang, Zhiqiang Wang and Xi Zhang Polym. Chem. 2014, 5, 5895-5899.

Remzi Becer is a web-writer and advisory board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information!

The synthesis of highly hemo- and cytocompatible zwitterionic 2-oxazoline-based poly(sulfobetaine)s and poly(carboxybetaine)s, which demonstrate beneficial anticoagulant activity, has been reported by Schubert et al.

The polymers were obtained by thiol–ene photoaddition of a tertiary amine-containing thiol onto an alkene-containing precursor copoly(2-oxazoline), followed by betainization with 1,3-propansultone and β-propiolactone. The polymers and their intermediates were characterized by means of 1H NMR spectroscopy and size exclusion chromatography. The influence of the zwitterionic polymers on the aggregation and hemolysis of erythrocytes, the whole blood viscosity, the platelet and complement activation as well as the blood coagulation has been studied in detail. In addition, the cytotoxicity of the materials has been evaluated.

It was found that the zwitterionic POx show no negative interactions with blood. Moreover, anticoagulant activity via the intrinsic and/or the common coagulation pathway was observed. The high hemocompatibility and the low cytotoxicity as well as the beneficial anticoagulant activity of the presented zwitterionic poly(2-oxazoline)s demonstrate their potential for the use in biomedical applications.

Zwitterionic poly(2-oxazoline)s as promising candidates for blood contacting applications by Lutz Tauhardt, David Pretzel, Kristian Kempe, Michael Gottschaldt, Dirk Pohlers and  Ulrich S. Schubert Polym. Chem. 2014, 5, 5751-5764.

Remzi Becer is a web-writer and advisory board member for Polymer Chemistry. He is currently a Senior Lecturer in Materials Science and the director of the Polymer Science and Nanotechnology masters programme at Queen Mary, University of London. Visit www.becergroup.com for more information!

Exploiting the coumarin dimerization mechanism upon UV irradiation at 365 nm, Foster and co-workers developed mechanically adaptive nanocomposites in which light can be used to change the materials properties. CNCs derived from tunicates were functionalized with 7-coumaryl-(6-isocyanatohexyl) carbamate to afford coumarin-derivatized CNCs (Cou-CNCs). Light-responsive nanocomposites were prepared by reinforcing a rubbery ethylene oxide–epichlorohydrin copolymer (EO–EPI) matrix with Cou-CNCs. The as-prepared nanocomposites show a significantly increased tensile storage modulus (E′) in comparison to the neat EO–EPI. The optically induced reaction between Cou-CNCs also reduced the swelling of the EO–EPI/Cou-CNC nanocomposites upon exposure to water as well as the extent of water-induced softening.

Photoswitchable nanocomposites made from coumarin-functionalized cellulose nanocrystals by Mahesh V. Biyani, Christoph Weder and E. Johan Foster Polym. Chem. 2014, 5, 5501-5508.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.

In this work, Ling, Hogen-Esch and co-workers reported a styrene-type macromonomer containing polyfluorene pendent group (PFS), which allowed the convenient synthesis of well-defined copolymers of PFS with t-butyl acrylate by both RAFT and ATRP polymerization methods. After hydrolysis, the amphiphilic copolymers self-assembled into photoluminescent nanoparticles in aqueous solution. When doped with selected dyes, the nanoparticles emitted light with tunable colors as well as white via Förster energy transfer from the excited pendent polyfluorene groups.

White light emission of multi-chromophore photoluminescent nanoparticles using polyacrylate scaffold copolymers with pendent polyfluorene groups by Chao Deng, Peng Jiang, Xiaobin Shen, Jun Ling and Thieo E. Hogen-Esch, Polym. Chem. 2014, 5, 5109-5115.

Julien Nicolas is a web-writer and advisory board member for Polymer Chemistry. He currently works at Univ. Paris-Sud (FR) as a CNRS researcher.