Well-defined pH-responsive glycopolypeptides were prepared by polymer-analogous aqueous amide coupling of d-glucosamine to poly(α,l-glutamic acid) (PGA) using the coupling agent 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM) without any organic solvents, additives, or buffers. Degrees of substitution (DS) up to 80% can be achieved, and the DS is adjustable by the molar ratio of DMT-MM to PGA repeating units. Successful glycosylation of both low MW and high MW PGA was confirmed by ¹H NMR and FTIR spectroscopy as well as by an enhanced solubility at low pH. CD spectroscopy revealed that glycosylated PGAs with a DS up to 0.63 are able to undergo a pH-responsive and reversible helix-coil transition. However, for polymers with higher DS no transition occurs. A comparison with PGAs functionalized with monoethanolamine showed that the low helicity at high DS is not a steric effect due to the bulky sugar moieties, but a solvation effect. Preliminary turbidimetric tests with the lectin Concanavalin A indicate a biological activity of these glycosylated polypeptides. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3925–3931

This study presents the synthesis of a crosslinkable dextran as starting material for the development of new hydrogels as drug delivery system in dental applications. 2-Hydroxyethyl methacrylate (HEMA) was coupled to dextran after activation with carbonyldiimidazole as monitored by FTIR and ¹H-NMR spectroscopy. The Dex-HEMA was crosslinked by visible light in the presence of camphorquinone (CQ) as photoinitiator and a coinitiator in a proper solvent. Aliphatic or aromatic amines were used as coinitiators and the content of the coinitiator was varied from 0.25 to 3.0 mol %. Diphenyliodonium chloride was added as a third component to the above photoinitiation system. It was observed that, the degree of swelling decreased upon an increase of Dex-HEMA concentration and the water content in the solvent system due to formation of more crosslinking points, that is, increasing crosslink density (P_x). The type of coinitiator shows a prominent impact on the swelling behavior and crosslinking efficiency of hydrogels. Special cryofixation and cryofracture techniques were used to investigate the surface and interior of swollen Dex-HEMA hydrogel samples by SEM. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Well defined azobenzene containing (co)polymers have been synthesized by atom transfer radical polymerization and subsequent polymeranalogeous reaction for introduction of the chromophores. Four different series were prepared varying only one of the following material parameters at a time, while keeping the others constant. Varied were the molecular weight, the azobenzene content, the glass transition temperature and the molecular architecture of the copolymers. With these four series of (co)polymers the influence of the molecular parameters on the photoinduced formation of surface relief gratings was investigated.

The synthesis of well-defined polypeptide-polyvinyl rod coil block copolymers via the combination of Nickel-mediated ring opening polymerization and atom transfer radical polymerization (ATRP) is described. The strategy for the synthesis is based on a bifunctional initiator. In the first step the poly-benzyl-L-glutamate (PBLG) block is prepared which is subsequently used as a macroinitiator for the ATRP of methyl methacrylate (MMA). These two reaction steps are performed either consecutively by isolation of the PBLG-macroinitiator or in a one-pot procedure without isolation of the PBLG-macroinitiator. By the one-pot approach the tedious isolation and purification of the macroinitiator is avoided. Reasonable PMMA-block lengths and low polydispersities indicate a successful synthesis of PBLG-PMMA block copolymers also via the one-pot procedure.

A bifunctional initiator was synthesized having two functional groups for the initiation of the nickel mediated ring-opening polymerization of γ-benzyl-l-glutamate-N-carboxyanhydride and for the controlled radical polymerization of styrene via NMP. Molecular weights and molecular weight distributions of the polypeptides and block copolymers (PBLG-b-PS) were measured by SEC/MALLS. The controlled character of the NMP of styrene was examined by investigation of monomer consumption by gas chromatography.