Inspired by the lotus leaf, scientists have developed many superhydrophobic surfaces, some of which show remarkable switching between hydrophobic and hydrophilic state under external stimuli. However, the switch usually relies on the change of chemical properties rather than on the modification of the topographic structure of the surface. In this paper, the roughness‐change‐related switchable wetting properties of microstructured responsive surfaces made of nematic liquid crystalline elastomers (LCEs) is reported. First, various carbonate LC monomers and side‐on LCEs are synthesized with low nematic‐to‐isotropic transition temperature, TNI. Then, LCEs prepared from 3″‐vinylcarbonyloxypropyl 2,5‐di(4′‐octyloxybenzoyloxy)benzoate monomer, with TNI of 76 °C and contraction of 34% are used to construct a surface covered with micropillar arrays by using a replica molding technique. The contraction of the micropillars induces a reversible roughness change of the microstructured surface. Water contact angle of this microstructured surface changed with temperature, indicating a successful approach at building a surface with switchable wetting properties.

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Abstract. Four wood pulps and a microcrystalline cellulose were dissolved in a NaOH 8% -water solution. Insoluble fractions and clear solution fractions were isolated by centrifugation and were observed by optical microscopy and transmission electron microscopy. Molecular weight distribution, carbohydrate composition and cellulose II content were measured. The dissolution of wood cellulose fibres in NaOH 8% -water solutions occurs by successive dismantlement and fragmentation steps governed by the swelling and the shearing of the original structure. The cellulose from insoluble and clear solution fractions is in both case converted in cellulose II and the insoluble fractions contain embedded mannans. Besides, the molecular weight distributions of cellulose from insoluble and clear solution fractions reveal the existence of heterogeneities in dissolution capacity of the cellulose chains, independent to the degree of polymerization, which are related to the chemical environment of the chains in the fibre structure.

Microalgae were considered in this work as a new resource for developing starch-based bioplastics. Ten green microalgae strains were screened at lab-scale for their ability to produce starch. A long run (800 h) two-stage accumulation strategy was designed with successive cultivation in sulfur-replete, then sulfur-depleted medium in autotrophic conditions. Starch content was assessed on cell lysate by enzymatic digestion of extracted starch into glucose. Chlamydomonas reinhardtii 11-32A strain was selected as it displayed a maximum starch-to-biomass ratio of 49%w/w, 460 h after being switched to a sulfur-deprived medium. Small-scale pilot production (30 L tubular photobioreactor) with C. reinhardtii 11-32A yielded sufficient biomass quantity to investigate its direct plasticization with glycerol in a twin-screw extruder. Microstructural characterization confirmed the ability for starch-enriched microalgae to be homogeneously plasticized, and hence the possibility to use microalgae as a new platform for the development of bioplastics.

This study investigates the effect of optimized organosilane treatments on the surface properties of flax fibres and the resulting mechanical properties and interface modifications in flax fibres reinforced poly(lactic acid) (PLA) biocomposites. Optimizing the treatment conditions increases the hydrophobicity of the fibres, and improves significantly the mechanical properties of the biocomposites, while reducing largely the scattering. The origins of the reinforcement at the fibre/matrix interface are investigated at the macromolecular and the microstructural levels by physico-chemical and mechanical cross-analyses. It is shown that it results from both modified chemical coupling and mechanical interlocking at the fibre/matrix interface. Dynamic mechanical thermal analysis reveals a decrease in damping for treated biocomposites because of the formation of a layer of immobilized macromolecular chains resulting from strong interactions at the interface. In situ observations of crack propagation by scanning elec-tron microscopy illustrate clearly that the treated biocomposites show a cohesive interfacial failure at much higher loads, highlighting the enhanced load transfer from the PLA to the flax fibres.

Industrial peptide synthesis is generally carried out in batches and suffers both from the production of tremendous amounts of toxic waste and the difficulty to handle solids. In this study, peptide couplings were performed at the multigram scale by using reactive extrusion in a CMRfree (CMR = Carcinogenic, Mutagenic or Reprotoxic), solidtolerant, fast, efficient and epimerization-free manner, opening the way for intensified and continuous industrial production of peptides.

International audienceAn extended dynamic and capillary rheological study of molten flax and sisal polypropylene (PP) composites was performed. Fiber concentration varied from 20 to 50 wt% and shear rate from 0.1 rad s-1 to 10,000 sŽ-1. Maleic anhydride-grafted-PP was used as compatibilizer; it strongly reduces PP and composite viscosity. Composites are yield-stress shear-thinning fluids with solid-like behavior being more pronounced at high fiber content. Composites do not obey Cox-Merz rule, which was explained by different macrostructures of the molten composites in parallel plates and capillary die geometries: random fiber orientation versus strong alignment in the flow direction, respectively. Theories describing the viscosity of suspensions of solid particles were applied to the composites studied and rheological parameters and maximal packing fiber volume fraction were calculated

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