Vinyl ethers and epoxides photoinduced copolymerization with perfluoropolyalkylether monomers

New perfluoropolyalkylether (PFPAE) monomers, chain extended with different alkyl groups and functionalized with vinyl ether or epoxide end-groups, were employed, together with trimethylolpropane trivinyl ether or trimethylolpropane triglycidyl ether, to produce fluorinated copolymers. The photoinduced cationic polymerization was investigated, and the PFPAE-based copolymer properties were thoroughly characterized. Interesting surface properties and two different values of refractive index were observed: thus, these fluorinated copolymers can be suitable materials for the manufacture of self-cleaning coatings and optical waveguides

Fracture of a biopolymer gel as a viscoplastic disentanglement process

We present an extensive experimental study of mode-I, steady, slow crack dynamics in gelatin gels. Taking advantage of the sensitivity of the elastic stiffness to gel composition and history we confirm and extend the model for fracture of physical hydrogels which we proposed in a previous paper (Nature Materials, doi:10.1038/nmat1666 (2006)), which attributes decohesion to the viscoplastic pull-out of the network-constituting chains. So, we propose that, in contrast with chemically cross-linked ones, reversible gels fracture without chain scission

Novel green route towards polyesters-based resin by photopolymerization of star polymers

International audienceBio-based star-shaped poly(ε-caprolactone)s (S-PCL) derived from sugar-based D-sorbitol as an initiator were obtained via solvent-free enzymatic ring-opening polymerization (eROP). The star S-PCL were converted into UV-curable maleates by employing maleic anhydride for subsequent crosslinking with tri(ethylene glycol) divinyl ether (DVE-3) in the presence of Darocur 1173 as a radical photoinitiator. The kinetics of the UV-induced radical copolymerization was monitored by real-time Fourier-Transform InfraRed (FTIR) spectroscopy, which revealed that the star S-PCL maleate/divinyl ether system was not scavenged by molecular oxygen (donor/acceptor polymerization). The UV-crosslinking reaction was fast (~10 s) to reach near quantitative conversions. The S-PCL maleate / divinyl ether liquid formulation cast on glass substrates successfully gave films upon UV-crosslinking. The thermal properties of the polymer films and their precursor polymers were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Finally, the crosslinked polymer film demonstrated promising adhesive properties on steel, aluminum and glass substrates

Use of Fluorinated Maleimide and Telechelic Bismaleimide for Original Hydrophobic and Oleophobic Polymerized Networks

International audienceThe syntheses of original fluorinated maleimide and telechelic bismaleimide bearing C6F13 and C6F12 groups, respectively, and their use as reactive additives in photopolymerizable formulations of telechelic poly(propylene glycol) bismaleimide (PPGBMI) are presented. That fluorinated maleimide was synthesized in five steps in 63% overall yield from C6F13C2H4I precursor whereas the fluorinated bismaleimide was prepared in six steps in 14% overall yield from IC6F12I. These latter led to fluorinated azido and diazido intermediates, which were reduced, into the fluorinated amine and diamine in two steps. The condensation of amine and diamine onto maleic anhydride offered an amic acid and a diamic acid, which were subsequently cyclized into fluorinated maleimide and bismaleimide. Formulations of telechelic poly(propylene glycol) bismaleimide containing a few amount of these fluorinated maleimide and bismaleimide were UV cured and the surface properties of the resulting films were investigated. A deep modification of the surface properties was noted. In all the cases, a selective enrichment of the fluorinated monomer at the film surface was observed

Integration of gastronomy and physics for innovation

<p>Abstract</p> <p>Integration of physics with gastronomy can yield innovations in an efficient manner. An important element of this integration is the structure of food. The creation of food recipes often deals with designing new structures and a clear understanding of how food structure influences food properties is necessary. The physics that is required for this understanding can be demonstrated by considering the case of gelatin. A Master of Science (MSc) specialization is described, which addresses the integration of physics with gastronomy in an educational setting at Wageningen University, The Netherlands.</p

Gorenflot, R. (1994). Biologie végétale. Plantes supérieures. 1. Appareil végétatif.

The synthesis of poly(vinylidene fluoride)-graft-oligomeric hexafluoropropylene oxide graft copolymers [poly[VDF-g-oligo(HFPO)-PIPE] is presented, where VDF, HFPO, and PIPE stand for vinylidene fluoride (CH2vCF2), hexafluoropropylene oxide (CF3CFCF2O) and, perfluoroisopropenylether (–OC(CF3)vCF2), respectively. First, an 82% isolated yield of oligo(HFPO)-PIPE macromonomer was achieved by using oligo(HFPO) primary iodide as the starting reagent. Then, the radical copolymerization of VDF with the PIPE comonomer, initiated by perfluoro-3-ethyl-2,4-dimethyl-3-pentyl persistent radical (PPFR), was studied under various conditions. The PPFR initiator, stable at room temperature, was able to release a •CF3 radical starting from 80 °C. The resulting poly[VDF-g-oligo(HFPO)-PIPE] graft copolymers were produced in good isolated yields (76 to 97%). The molar percentages and molar masses of such graft copolymers were assessed by 19F-NMR spectroscopy using the CF3– end-group label. The molar percentages of VDF and oligo(HFPO)-PIPE comonomers reached up to 99% and 20%, respectively, while the molar masses ranged between 7500 and 42 600 g mol−1. Their thermal properties showed: (i) fair to satisfactory thermostability (T5%d ) showing up to 271 °C under nitrogen, (ii) glass transition (Tg) ranged from −81 to −82 °C while (iii) their melting temperature (Tm) ranged between 150 and 163 °C. Moreover, the synthesized copolymers were demonstrated to be highly omniphobic (i.e., simultaneously hydrophobic and oleophobic), showing a water contact angle of ca. 133°, a hexadecane contact angle ca. 70°, and a surface energy as low as 12 mN m−1