Reversible addition–fragmentation chain transfer (RAFT) was applied to the copolymerization of styrene and maleic anhydride. The product had a low polydispersity and a predetermined molar mass. Novel, well‐defined polyolefin‐based block copolymers were prepared with a macromolecular RAFT agent prepared from a commercially available polyolefin (Kraton L‐1203). The second block consisted of either polystyrene or poly(styrene‐co‐maleic anhydride). Furthermore, the colored, labile dithioester moiety in the product of the RAFT polymerizations could be removed from the polymer chain by UV irradiation. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3596–3603, 2000

Pulsed laser-induced polymerization (PLP) in combination with analysis of formed polymer by size exclusion chromatography (SEC) has been successfully applied in determining propagation rate coefficient, k p, of acrylic and methacrylic acid in organic solvents and water. For methacrylic acid solution polymerization in methanol and in dimethyl sulfoxide (DMSO), minor but not negligible variations of k p with solvent have been observed. In contrast, k p values for polymerizations in water are significantly influenced by the solvent and furthermore by monomer concentration. The k p values obtained from polymerization experiments in water are significantly larger than the corresponding values obtained in methanol or DMSO. Weighted nonlinear least-squares fitting (NLLS) has been applied to calculate frequency factors, A, and activation energies, E a, from the temperature dependence of k p for methacrylic acid in methanol, DMSO, and water in order to underline the reliability of the data. For acrylic acid it turns out that optimized experimental conditions have to be chosen in order to determine reliable k p values at ambient temperature. Laser pulse repetition rates of at least 90 Hz are necessary to ensure that “termination by the laser pulse” is the main chain stopping event. Smaller values of the laser pulse repetition rate will not yield reliable k p data. Furthermore, evidence of at least one first overtone inflection point at L 2 ≈ 2L 1 is not only recommended, it is necessary to ensure a reliable measure of k p. This is the most important consistency criterion showing that experimental conditions are suitable.

Silica‐coated vesicles have been produced by the deposition of silica onto unilamellar vesicles from aqueous solution for the first time. The quaternary ammonium surface of the surfactant vesicles is receptive to silica and facilitates deposition of up to 5–10 nm of it. The “petrified” vesicles are stable to dehydration and can be visualized by conventional TEM (see Figure) without additional staining agents.

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