Summary: Polydimethylsiloxane with trimethylammonium end groups and polydimethylsiloxane with diethylmethylammonium groups in the main chain was prepared by two routes. A novel carbonate coupler – (2‐oxo‐1,3‐dioxolan‐4‐yl) methyl phenyl carbonate – and the amine compounds α,ω‐(3‐aminopropyl) polydimethylsiloxane, 3‐(dimethylamino)‐1‐propylamine, and bis(2‐amino ethyl)amine served as the starting materials. The polymers obtained are hydrophobic and contain ammonium groups suitable for interaction with negatively charged surfaces. Thus these materials can be used for special surface modifications. Thin films were prepared by spin‐coating. Their morphology and properties were determined by means of optical microscopy, SFM, and contact angle measurements. The particle size distribution in aqueous solution of the vesicles formed was determined by means of a laser scattering technique; the particle sizes determined correspond to those obtained by optical microscopy. Finally, the antibacterial effects of these polymers with hydrophobic and cationic groups were tested.α,ω‐Diammonium octadimethylsiloxane molecule (6), an SFM phase image for a spin‐coated film of 6 on a silicon wafer, and a scheme of the way the molecules stack on the surface.magnified imageα,ω‐Diammonium octadimethylsiloxane molecule (6), an SFM phase image for a spin‐coated film of 6 on a silicon wafer, and a scheme of the way the molecules stack on the surface.
Cover: Due to thermodynamical reasons, ethylene carbonate (EC) and 1,2-propylene carbonate (PC) are monomers which cannot be homopolymerized to polycarbonates with uniform microstructure. However, copolymerization of EC and PC with tetramethylene urea (TeU) leads to polyurethanes with randomly distributed TeU-EC/TeU-PC units. It was found that the reactivity of PC is significantly lower than that of EC. The properties of the polyurethanes are determined by the ratio of EC to PC which was deduced from 1 H NMR analysis. This isocyanate-free route to polyurethanes is of ecological importance.
Summary: Tetramethylene urea (TeU, 1) is successfully copolymerized with 1,2‐propylene carbonate (PC, 2) leading to a polyurethane ($\overline M _{\rm n}$ = 12 200; $\overline M _{\rm w}$ 18 400; $\overline M _{\rm w} /\overline M _{\rm n}$ = 1.50) with a Tm of 145.7 °C and a Tg of 53.7 °C. Mechanistic studies with a blocked isocyanate model compound revealed that, at no stage of the reaction is the TeU ring opened to form an isocyanate. Hence, a well‐underlined mechanism for the copolymerization is proposed. Furthermore, TeU is successfully copolymerized with mixtures of PC and ethylene carbonate (EC, 3). From NMR spectroscopic data of the polyurethanes obtained, it is concluded that PC is less reactive than EC. However, it is possible to increase the PC content in poly(TeU‐EC‐stat‐TeU‐PC) by increasing the PC/EC ratio in the feed. 13C NMR spectroscopy reveals that a random copolymer is obtained. This conclusion is supported by differential scanning calorimetry (DSC) data, which show a continuous decrease in Tm with increasing PC content.Tm was found to decrease with increasing PC content.imageTm was found to decrease with increasing PC content.
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