In nitroxide-mediated polymerization, NMP, the role of the initiation and therefore the role of the initiating dissociation rate constant k d1 on the control and livingness of a styrene and n-butyl acrylate polymerization was investigated. Different polymerizations were carried out, initiated with two different alkoxyamines based on the same nitroxide (1 • or SG1). Kinetic modeling studies using the PREDICI software are used to explain these results. The use of a new tertiary SG1-based alkoxyamine 1a instead of the secondary SG1-based alkoxyamine 1b improved the control of the polymerization of both styrene and n-butyl acrylate. In particular, the polymerization of n-butyl acrylate can be carried out without adding any extra initial amount of nitroxide and the controlled polymerization of styrene at 90 °C is now possible. The complete kinetic analysis showed that the main role of the alkoxyamine with a high dissociation rate constant is to produce quickly in situ an extra amount of free nitroxide, which is necessary to obtain a good control of a polymerization. Moreover, we linked theoretically the threshold k d1 value necessary to have a good controlled and living polymerization in a true monocomponent system with the value of the propagation rate constant k p. This new statement (k p/k d1 ≤ 6.0 × 105 L·mol-1) has to be added to Fischer's equations to determine the optimum experimental conditions to obtain a successful polymerization. Furthermore, the results showed clearly the importance of the experimental procedure (heating with a ramp of temperature or not, purity of the monomers and the vessels) to obtain a successful living/controlled polymerization.

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Use of LAPONITE® clay platelets as Pickering stabilizers of vinylidene chloride-based latexes.

The incorporation of heteroatoms into the backbone of commodity polymers prepared by radical polymerization is an elegant way to confer (bio)degradability to such materials. This could be achieved via the radical ring-opening polymerization of cyclic monomers. Thionolactones were recently identified as promising comonomers for rROP but only reacting with activated monomers such as acrylate and acrylamide derivatives. Herein, we describe two thionolactone monomers, oxepane-2-thione i.e. εthiono-caprolactone (thCL) and 7-butyloxepane-2-thione, i.e ε-thiono-decalactone (thDL) capable of performing radical ringopening polymerization with less activated monomers such as vinyl acetate (VAc) to produce readily degradable copolymers via the insertion of thioester containing repeating units. A thorough mechanistic investigation was performed to understand the reactivity of the two cyclic monomers. We identified the initiation as the main parameter to perform the polymerization of such thionolactone monomers. In a specific case the poly(ε-thCL) homopolymer was successfully obtained. Concerning the copolymerization with vinyl acetate, a variety of polymerizations with differing feed ratios were performed, and the degradability of the copolymers via aminolysis examined by SEC. To demonstrate the usefulness of thionolactones a variety of block copolymers containing thioester linkages involving N,N-dimethylacrylamide and VAc were also prepared and degraded.

The effect of the penultimate unit on the CON bond homolysis rate constant kd was studied for model alkoxyamines. It was shown that the kd for fragments containing penultimate and antepenultimate units were nicely predicted by the tri‐parametric relationship developed in Macromolecules 2005, 38, 2638 and Eur. J. Org. Chem. 2006, 7, 1755 (log kd = −14.33 + 15.06 × σRS + 20.00 × σI + 6.96 × υ). A striking effect was observed only for a tert‐butyl‐like group as the penultimate unit.

Thermolysis of alpha-alkoxyamino propionanilides produces indolinones, whereas thermal reaction of N-allylaniline derivatives with various Tordo-type alkoxyamines results in formation of indolines in the radical regime. [reaction: see text]

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International audienceThis review described the potential of the intermolecular radical 1,2-addition from the commercially available BlocBuilder MA alkoxyamine onto activated olefins to synthesize either new functionalized alkoxyamines or various macromolecular architectures. Following this approach, diblock, triblock copolymers, star polymers and hybrid materials are then easily prepared. The various applications of such architectures will be briefly reviewed. Interestingly this new synthetic tool widely expands the range of complex macromolecular architectures which could be obtained by the nitroxide-mediated polymerization (NMP) process