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Silicone coatings with enhanced antifouling behavior towards bacteria, diatoms, and a diatom dominated slime were prepared by incorporating PEO-silane amphiphiles with varied siloxane tether lengths (a-c): α-(EtO)3Si(CH2)2-oligodimethylsiloxanen-block-poly(ethylene oxide)8-OCH3 [n = 0 (a), 4 (b), and 13 (c)]. Three modified silicone coatings (A-C) were prepared by the acid-catalyzed sol-gel cross-linking of a-c, respectively, each with a stoichiometric 2:3 M ratio of α, ω-bis(Si-OH)polydimethylsiloxane (Mn = 3,000 g mol(-1)). The coatings were exposed to the marine bacterium Bacillus sp.416 and the diatom (microalga) Cylindrotheca closterium, as well as a mixed community of Bacillus sp. and C. closterium. In addition, in situ microfouling was assessed by maintaining the coatings in the Atlantic Ocean. Under all test conditions, biofouling was reduced to the highest extent on coating C which was prepared with the PEO-silane amphiphile having the longest siloxane tether length (c).

International audienc

One of the most promising alternatives to toxic heavy metal-based paints is offered by the development of antifouling coatings in which the active ingredients are compounds naturally occurring in marine organisms and operating as natural antisettlement agents. Sessile marine macroalgae are remarkably free from settlement by fouling organisms. They produce a wide variety of chemically active metabolites in their surroundings, potentially as an aid to protect themselves against other settling organisms. In this study, a dichloromethane extract from the brown seaweed Sargassum muticum was tested in situ and, after 2 months of immersion, showed less fouling organisms on paints in which the extract was included, compared to paints containing only copper after 2 months of immersion. No barnacles or mussels have been observed on the test rack. Identification by NMR and GC/MS of the effective compound revealed the abundance of palmitic acid, a commonly found fatty acid. Pure palmitic acid showed antibacterial activity at 44 µg mL −1, and also inhibited the growth of the diatom Cylindrotheca closterium at low concentration (EC 50 =45.5 µg mL −1 ), and the germination of Ulva lactuca spores at 3 µg mL −1 . No cytotoxicity was highlighted, which is promising in the aim of the development of an environmentally friendly antifouling paint.

Summary: Novel polyester and copolyesters have been prepared by anionic ring‐opening polymerization of racemic 4‐alkyloxycarbonyl‐3,3‐dimethyl‐2‐oxetanones that had been synthesized in five steps from diethyl oxalpropionate used as chemical precursor. The anionic polymerizations, realized in bulk or in solution with tetraethylammonium benzoate as initiator, led to a homopolymer and copolymers with high molecular weights and polydispersity indices close to unity. These features can be explained by the presence of two methyl groups on the same carbon atom in the lactone, preventing transfer reactions to the monomer. Preparation of seeds and re‐initiation by addition of fresh monomer confirmed a living process. The hydrolysis of poly[(R,S)‐3,3‐dimethylmalic acid] under physiological conditions yielded (R,S)‐3,3‐dimethylmalic acid. A terpolymer was also prepared for biological studies related to its use as biodegradable materials for tissue regeneration.Structure of poly[(R,S)‐3,3‐dimethylmalic acid].imageStructure of poly[(R,S)‐3,3‐dimethylmalic acid].

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International audienceThe objectives of this study are to observe the effects of the introduction of polydimethylsiloxane (PDMS) on the hydration and degradation of aliphatic polyesters in water, such as poly(ε-caprolactone) (PCL). The mechanism of PCL degradation in water is well known, and PDMS is a nonbiodegradable and hydrophobic polymer. The ligation of these two polymers should allow the synthesis of new polymers with hybrid properties in terms of degradation and surface energy. The deterioration in water should be controlled by the ratio of each polymer. The triblock copolymers were synthesized through ring opening polymerization with stannous octanoate as the catalyst. A film of each copolymer was prepared and immersed in distilled water to study their aging. Kinetic results of hydration and degradation show that the addition of PDMS on PCL does not change the profiles of hydration and degradation. But the variation of the structure of the triblock (molecular weight or ratio of each block) allows to increase or decrease the rate of hydration, so as to control its degradation

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