We report about modification of poly(N-vinylpyrrolidone) (PVP) with monofunctional β-cyclodextrin (βCD) via click-chemistry. The modification was carried out by copper(I)-catalyzed microwave-assisted Huisgen-type cycloaddition of 3-propargyl-N-vinylpyrrolidone (2a) and mono(6-azido-6-deoxy)-β-cyclodextrin (3). We synthesized a copolymer (5) carrying CD moieties which has the same composition as the applied molar ratio of monomers. Complexation experiments of the obtained polymer (5) with phenolphthalein (PP) showed a lower binding constant compared to βCD caused by sterical effects of the polymer coil.

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PurposeTo investigate the antibacterial effect and the effect on the material properties of a novel delivery system with Irgasan as active agent and methacrylated polymerizable Irgasan when added to experimental dental resin composites.Materials and MethodsA delivery system based on novel polymeric hollow beads, loaded with Irgasan and methacrylated polymerizable Irgasan as active agents were used to manufacture three commonly formulated experimental resin composites. The non-modified resin was used as standard (ST). Material A contained the delivery system providing 4 % (m/m) Irgasan, material B contained 4 % (m/m) methacrylated Irgasan and material C 8 % (m/m) methacrylated Irgasan. Flexural strength (FS), flexural modulus (FM), water sorption (WS), solubility (SL), surface roughness Ra, polymerization shrinkage, contact angle Θ, total surface free energy γS and its apolar γS LW, polar γS AB, Lewis acid γS +and base γS - term as well as bacterial viability were determined. Significance was p < 0.05.ResultsThe materials A to C were not unacceptably influenced by the modifications and achieved the minimum values for FS, WS and SL as requested by EN ISO 4049 and did not differ from ST what was also found for Ra. Only A had lower FM than ST. Θ of A and C was higher and γS AB of A and B was lower than of ST. Materials A to C had higher γS + than ST. The antibacterial effect of materials A to C was significantly increased when compared with ST meaning that significantly less vital cells were found.ConclusionDental resin composites with small quantities of a novel antibacterially doped delivery system or with an antibacterial monomer provided acceptable physical properties and good antibacterial effectiveness. The sorption material being part of the delivery system can be used as a vehicle for any other active agent.

The monomer 3-ethyl-1-vinyl-2-pyrrolidone (3) and the homopolymer poly(3-ethyl-1-vinyl-2-pyrrolidone) (5) have been synthesized. Polymer 5 is soluble in water and shows a critical temperature (T(c) ) of 27 °C. The presence of cyclodextrin causes a slight shift of the T(c) . The lower critical solution temperature (LCST) could be varied between 27 and 40 °C by copolymerization with N-vinyl-2-pyrrolidone. A linear correlation between the T(c) and the copolymer composition is observed.

Using isocyanate-functionalized Kraft lignin as a reactive macromonomer for the preparation of polyurethane foams by a prepolymer technique is a well-known strategy to incorporate the biomacromolecule into a higher value polymer material. However, as of today the mechanical properties of the resulting materials are still insufficient for a number of possible applications. One reason for this limitation is that the reaction pathway and the morphological arrangement of such foams is of uttermost complexity and depends on a large number of influencing material-intrinsic factors. One important parameter is the reactivity of the functionalized lignin, which has a great impact on the interphase reaction kinetics and thus, on the geometry and mechanical properties of the resulting polyurethane foams. The reactivity is implied, amongst others, by the electron affinity of the isocyanate moiety. Herein, we investigate the reactivity of Kraft lignin modified with different commercially used isocyanates in the reaction with conventional polyols. Therefore, differently reactive prepolymers were synthesized, characterized and polyurethane foams were prepared thereof by using these compounds and the foam formation kinetics, morphological as well as mechanical properties were investigated. Finally, the results were supported by quantum mechanical calculations of the electron affinities of representative model compounds for the lignin-based prepolymers. This work gives rise to a better understanding of the effect of the reactivity and isocyanate structure linked to Kraft lignin on the polyurethane formation and enables rational choice of the isocyanate for pre-functionalization of lignin to prepare materials with better mechanical performance.