Propagation and chain‐length averaged termination rate coefficients, kp and <kt>, for radical polymerizations of methacrylates carrying poly(ethylene glycol) (PEG) units are reported. kp derived from pulsed laser initiated polymerizations in bulk, in organic solvents, and in ionic liquids follows the methacrylate‐type family behavior. Contrary, diffusion controlled kt values obtained from chemically initiated polymerizations with in‐line FT‐NIR monitoring of monomer conversion are strongly affected by the PEG units in the ester group. Compared to alkyl methacrylates <kt> is unexpectedly high. Moreover, <kt> of poly(ethylene glycol) ethyl ether methacrylate shows a significant reduction in kt already at 15% conversion, whereas dodecyl methacrylate <kt> is constant up to at least 70% conversion.magnified image

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For the first time individual propagation rate coefficients, k p, for the homopolymerization of vinylidene fluoride (VDF) have been determined in homogeneous phase reactions with supercritical carbon dioxide. Experiments combining pulsed laser initiation and polymer analysis by size-exclusion chromatography were carried out for temperatures up to 90 °C and pressures up to 1100 bar. Absolute polymer molar masses required for the determination of k p were calculated on the basis of experimentally derived Mark–Houwink constants. A general equation k p(VDF) = f(p,T) was derived by applying multiple regression analysis of k p data. All data may be expressed by ln[k p/(L·mol–1·s–1)] = 19.96 – 3633 K/T + 0.27 p/bar × T –1/K–1. Due to the fluorine atoms in the monomer the kinetic data is significantly different from the nonfluorinated structural analogue ethene. For example, at 60 °C and 1000 bar VDF k p is 19400 L·mol–1·s–1, while k p for ethene is by a factor of 200 lower.

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The propagation kinetics and copolymerization behavior of the biorenewable monomer γ-methyl-α-methylene-γ-butyrolactone (MeMBL) are studied using the pulsed laser polymerization (PLP)/size exclusion chromatography (SEC) technique. The propagation rate coefficient for MeMBL is 15% higher than that of its structural analogue, methyl methacrylate (MMA), with a similar activation energy of 21.8 kJ·mol(-1). When compared to MMA, MeMBL is preferentially incorporated into copolymers when reacted with styrene (ST), MMA, and n-butyl acrylate (BA); the monomer reactivity ratios fit from bulk MeMBL/ST, MeMBL/MMA, and MeMBL/BA copolymerizations are r(MeMBL) = 0.80 ± 0.04 and r(ST) = 0.34 ± 0.04, r(MeMBL) = 3.0 ± 0.3 and r(MMA) = 0.33 ± 0.01, and r(MeMBL) = 7.0 ± 2.0 and r(BA) = 0.16 ± 0.03, respectively. In all cases, no significant variation with temperature was found between 50 and 90 °C. The implicit penultimate unit effect (IPUE) model was found to adequately fit the composition-averaged copolymerization propagation rate coefficient, k(p,cop), for the three systems.