Laccase from Trametes versicolor is a multi-copper-containing oxidoreductase which was found to catalyze the polymerization of N-vinylimidazole under conditions of atom transfer radical polymerization (ATRP) in aqueous solution (pH 4, 100 mM acetate buffer) at ambient temperature by using sodium ascorbate as a reducing agent. The reaction followed first order kinetics and resulted in polymers with controlled number-average molecular weights (between 1660 and 9970 g mol⁻¹) and relatively narrow, monomodal molecular weight distributions (Đ between 1.27 and 1.56) according to gel permeation chromatography. Purified polymers were also analyzed by mass spectrometry which revealed a Đ of 1.07. The enzyme could be separated quantitatively from the polymer, lowering the metal content of the purified polymers below the detection limit of ICP-OES of 9 ppb. The enzyme retained its polymerization activity for more than eight hours, but formed electrostatic complexes with the polymer and underwent conformational changes at the beginning of the reaction. Biocatalytic controlled radical polymerization allows the synthesis of poly(N-vinylimidazole) with a well-defined molecular weight. Such polymers will be useful building blocks in many applications, such as drug- and gene-delivery, fuel cell membranes and polyionic liquids.

Unexpected correlations have been found between structural parameters and glass transition temperatures (T_g) of poly(N-vinylimidazole) (PVIm) and crystallinity of poly(tetrahydrofuran) (PTHF) in a series of novel, unique PVIm-l-PTHF amphiphilic conetworks synthesized in broad composition ranges via free radical copolymerisation of VIm and semicrystalline, methacrylate-telechelic PTHF macromolecular cross-linkers with varying M_n from 2170 to 10 000 g mol⁻¹. Differential scanning calorimetry (DSC) investigations revealed microphase separation between the covalently bonded PVIm and PTHF components, that is two distinct T_gs corresponding to the respective polymers (PVIm and PTHF) were obtained in these optically clear, transparent materials. Complete microphase separation, i.e. absence of mixed phases, was also confirmed by solid state NMR measurements. The T_g of the PVIm phase significantly decreases with increasing PTHF content, and Fox–Flory type correlation was surprisingly found between the T_g of PVIm and its M_c (average molecular weight between cross-links). This striking finding indicates a unique, unpredicted scissor effect of the macromolecular PTHF cross-linker in these materials, i.e. with respect to glass transition, PVIm behaves as individual chains between cross-links. The molecular mobility in the PVIm chain segments obtained by solid state NMR investigations shows a similar trend as a function of M_c. In the DSC thermograms, the semicrystalline PTHF has a sharp endothermic melting peak (T_m) indicating partial crystallisation of this polymer. It was found that the T_m and the crystalline fraction (X_c) of the PTHF phase are suppressed by even a minimal content of PVIm phase in the conetworks. Even complete diminishing of X_c occurs in conetworks with lower than 40 wt% PTHF of the lowest M_n (2170 g mol⁻¹). Unexpectedly, T_m linearly decreases with M_c in conetworks with constant M_n of PTHF. These data indicate that the decrease of both T_m and X_c of PTHF is not only composition dependent, but the MW of the macromolecular PTHF cross-linker and the M_c of the PVIm component also have effects on these parameters. These results also indicate that chemical bonding of polymer chains in conetworks yields novel materials with unprecedented property variation. This provides unique opportunities for fine tuning of the investigated fundamental material properties, i.e. T_g, T_m and X_c, within certain ranges in the novel PVIm-l-PTHF amphiphilic conetworks by selecting the proper synthesis parameters, that is, composition and MW of the telechelic PTHF macromonomer cross-linker.

Macroscopically homogeneous poly(N-vinylimidazole)-linked by-poly(tetrahydrofuran) (PVIm-l-PTHF) amphiphilic conetworks (APCNs) were investigated to reveal the effect of conetwork composition in a broad composition range between 25–91 wt% PTHF content and the molecular weight of the components on phase separation and the formation of different morphological features. No macroscopic phase separation was found in these conetworks with semicrystalline PTHF phase, but the segregation of the various covalently connected phases occurs in the nanoscale. The nanophase separated APCNs possess compositionally asymmetric morphology with spherical and elongated domains together with a bicontinuous (cocontinuous) domain structure having ∼7–19 nm average domain sizes. The molecular weight of the PTHFDMA cross-linker, varying between 2170 and 10 030 g mol⁻¹, also influences the size and distance between the phases. Moreover, morphology dependent interactions with polar and non-polar solvents, as well as amphiphilic swelling behavior were found. These nanostructured materials, due to their unique nanophasic morphology and swelling properties possess significant importance and have numerous potential applications in various fields from medicine to material science and engineering.