It is discovered that the memory‐type behaviors of novel carbohydrate‐block‐polyisoprene (MH‐b‐PI) block copolymers‐based devices, including write‐once‐read‐many‐times, Flash, and dynamic‐random‐access‐memory, can be easily controlled by the self‐assembly nanostructures (vertical cylinder, horizontal cylinder, and order‐packed sphere), in which the MH and PI blocks, respectively, provide the charge‐trapping and stretchable function. With increasing the flexible PI block length, the stretchability of the designed copolymers can be significantly improved up to 100% without forming cracks. Thus, intrinsically stretchable resistive memory devices (polydimethylsiloxane(PDMS)/carbon nanotubes(CNTs)/MH‐b‐PI thin film/Al) using the MH‐b‐PI thin film as an active layer is successfully fabricated and that using the MH‐b‐PI12.6k under 100% strain exhibits an excellent ON/OFF current ratio of over 106 (reading at −1 V) with stable V set around −2 V. Furthermore, the endurance characteristics can be maintained over 500 cycles upon 40% strain. This work establishes and represents a novel avenue for the design of green carbohydrate‐derived and stretchable memory materials.

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International audiencePhotosensitive amphiphilic linear polyoxazolines (CoumC 11-POx n) bearing alkyl chain decorated by a UV-active coumarin end group have been synthesized by cationic ring-opening polymerization (CROP). Using DLS and DOSY NMR experiments, their self-assemblies in water were compared with those of homologous photo-unreactiveamphiphilic polyoxazolines (C m-POx n). In both cases, spherical nanoparticles with D H-values around 10 nm were observed. The CoumC 11-POx n nanoparticles were illuminated upon 300 nm inducing the photo-dimerization of the coumarin units located in theinnercompartment of the nanoparticles. Finally, the pros and the cons of the photo-dimerization of linear copolymersrelated to the photo-crosslinking of graft copolymerswere discussed

Summary: Star‐like polystyrenes composed of a microgel core with arms functionalized with a few hydroxy‐ or methoxy‐ended ethylene oxide units were used as organic supports for a tridentate bis(imino)pyridinyliron catalyst towards ethylene polymerization. When used as supports of 2,6‐bis[1‐2,6(diisopropylphenyl)imino]ethylpyridynyl iron dichloride in the presence of various alkylaluminium compounds, the supported catalysts enabled the production, with a high catalytic activity, of polyethylene beads of a spherical morphology and high bulk density. A good control of the polyethylene molar mass distribution could also be achieved, which was explained by a lowering of the transfer reaction to the aluminium derivative, as compared to homogeneous conditions.SEM image of PE particles prepared in the presence of trimethylaluminium supported on a PS microgel with an iron catalyst (TMA/Fe = 800).imageSEM image of PE particles prepared in the presence of trimethylaluminium supported on a PS microgel with an iron catalyst (TMA/Fe = 800).

The synthesis and the solution-state self-assembly of the "hybrid" diblock copolymers, maltoheptaose-block-poly(methyl methacrylate) (MH-b-PMMA), into large compound micelles (LCMs) and reverve micelle-type nanoparticles, are reported in this paper. The copolymers were self-assembled in water and acetone by direct dissolution method, and the morphologies of the nanoparticles were investigated by dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), atomic force microscopy (AFM), proton nuclear magnetic resonance ((1)H NMR), and fluorescence spectroscopy as a function of the volume fraction of the copolymer hydrophobic block, copolymer concentration, stirring speed, and solvent polarity. The DLS measurements and TEM images showed that the hydrodynamic radius (Rh) of the LCMs obtained in water increases with the copolymer concentration. Apart from that, increasing the stirring speed leads to polydispersed aggregations of the LCMs. On the other hand, in acetone, the copolymers self-assembled into reverse micelle-type nanoparticles having Rh values of about 6 nm and micellar aggregates, as revealed the results obtained from DLS, AFM, and (1)H NMR analyses. The variation in micellar structure, that is, conformational inversion from LCMs to reverse micelle-type structures in response to polarity of the solvent, was investigated by apparent water contact angle (WCA) and (1)H NMR analyses. This conformational inversion of the nanoparticles was further confirmed by encapsulation and release of hydrophobic guest molecule, Nile red, characterized by fluorescence spectroscopy.

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Starlike polystyrenes composed of a microgel core and arms terminated with benzophenone groups were used as organic supports for a tridentate bis(imino)pyridinyliron catalyst for ethylene polymerization in the presence of trimethylaluminum as a cocatalyst. The microgels were synthesized by the atom transfer radical polymerization of styrene initiated by 4‐(1‐bromoethyl)‐benzophenone, with divinylbenzene as the crosslinker. The bromine polystyrene chain ends prevented the ethylene polymerization reaction and had to be removed. This was readily achieved with Cu0 together with dodecanethiol as a transfer agent. When used as supports in the presence of trimethylaluminum and 2,6‐bis[1‐2,6(diisopropylphenyl)imino]ethylpyridynyl iron, these bromine‐free, functionalized polystyrene stars enabled the production of polyethylene beads of a spherical morphology and high bulk density with a catalytic activity similar to that under homogeneous reaction conditions. Moreover, the molar mass distribution of the polyethylene was narrow, suggesting limited transfer to trimethylaluminum. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6997–7007, 2006

International audienceNew micelle-like organic supports for single site catalysts based on the self-assembly of polystyrene-b-poly(4-vinylbenzoic acid) block copolymers have been designed. These block copolymers were synthesized by sequential atom transfer radical polymerization (ATRP) of styrene and methyl 4-vinylbenzoate, followed by hydrolysis. As evidenced by dynamic light scattering, self-assembly in toluene that is a selective solvent of polystyrene, induced the formation of micelle-like nanoparticles composed of a poly(4-vinylbenzoic acid) core and a polystyrene corona. Further addition of trimethylaluminium (TMA) afforded in situ MAO-like species by diffusion of TMA into the core of the micelles and its subsequent reaction with the benzoic acid groups. Such reactive micelles then served as nanoreactors, MAO-like species being efficient activators of 2,6-bis[1-{(2,6-diisopropylphenyl)imino}ethyl]pyridinyl iron toward ethylene polymerization. These new micelle-like organic supports enabled the production of polyethylene beads with a spherical morphology and a high bulk density through homogeneous-like catalysis