Polymer Chemistry Blog

Yang et al. have developed a one pot approach to prepare polymer-carbon nanotube conjugates.

A hexa-component system has been successfully developed for simple polymer conjugation on carbon nanotubes. The well-known Ugi reaction has been recognized as a multicomponent click (MCC) reaction to efficiently collaborate with π–π stacking and RAFT polymerization to construct this delicate one-pot system. The CNT–(co)polymer composites inherit the properties of the conjugated polymers and can be well dispersed in both organic and aqueous solvents. As a simple and efficient method, this one-pot system might have the potential to become a general approach to prepare carbon-based composites.

Koda et al have developed amphiphilic/fluorous random copolymers bearing poly(ethylene glycol) (PEG) chains and perfluorinated alkane pendants as novel non-cytotoxic polymers for protein conjugation.

Three kinds of random copolymers with different initiating terminals (carboxylic acid, pyridyl disulfide, and N-hydroxysuccinimide ester) were prepared by reversible addition–fragmentation chain transfer (RAFT) copolymerization of a PEG methyl ether methacrylate and a perfluorinated alkane methacrylate with the corresponding functional chain transfer agents. All of the polymers were soluble in water to form nanostructures with perfluorinated compartments via fluorous interaction: large aggregates from the intermolecular multi-chain association and compact unimer micelles from the intramolecular single-chain folding. Such a PEGylated and perfluorinated random copolymer was non-cytotoxic to NIH 3T3 mouse embryonic fibroblast cells and human umbilical vein endothelial cells (HUVECs). Additionally, a random copolymer with a pyridyl disulfide terminal was also successfully conjugated with a thiolated lysozyme.

Quek et al present the synthesis and effect of end-groups on aqueous inverse temperature solubility of these polymers

A series of five novel R-group di-functional phenyl dithiobenzoates have been prepared and utilized in the controlled reversible addition–fragmentation chain transfer (RAFT) radical polymerization of 2-vinyl-4,4-dimethylazlactone (VDMA), yielding a series of homopolymers of similar average degrees of polymerization but variable α-end group functionality. Each of the reactive polyVDMA homopolymers was reacted with four different small molecule amines: dimethylamine, diethylamine, N,N-diethylethylenediamine and tetrahydrofurfurylamine yielding a series of novel end-functional materials. The effect of the end-groups on the inverse temperature dependent aqueous solubility of the formally hydrophilic homopolymers was then measured and compared to similar materials prepared with benzylpropyltrithiocarbonate as the RAFT agent. In virtually all instances, the introduction of the twin α-end-groups resulted in overall more hydrophobic species that exhibited cloud points spanning the range 25.1–42.7 °C. Importantly, there was a strong influence on the nature of the end groups and the associated solubility characteristics with, in some cases, cloud point behaviour only being observed in polymers with twin end groups while those derived from benzylpropyltrithiocarbonate were fully soluble.

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.

Ma et al present the pristine and thermally rearranged gas separation membranes.

A novel o-hydroxyl-functionalized spirobifluorene-based diamine monomer, 2,2′-dihydroxyl-9,9′-spirobifluorene-3,3′-diamine (HSBF), was successfully prepared by a universal synthetic method. Two o-hydroxyl-containing polyimides, denoted as 6FDA-HSBF and SPDA-HSBF, were synthesized and characterized. The BET surface areas of 6FDA-HSBF and SPDA-HSBF are 70 and 464 m² g⁻¹, respectively. To date, SPDA-HSBF exhibits the highest CO₂ permeability (568 Barrer) among all hydroxyl-containing polyimides. The HSBF-based polyimides exhibited higher CO₂/CH₄ selectivity than their spirobifluorene (SBF) analogues (42 for 6FDA-HSBF vs. 27 for 6FDA-SBF) due to an increase in their diffusivity selectivity. Polybenzoxazole (PBO) membranes obtained from HSBF-based polyimide precursors by thermal rearrangement showed enhanced permeability but at the cost of significantly decreased selectivity.

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!