Photoactive Polyoxometalate/DASA Covalent Hybrids for Photopolymerization in the Visible Range

International audienc

Light and Hydrogels: A New Generation of Antimicrobial Materials

Nosocomial diseases are becoming a scourge in hospitals worldwide, and new multidrug-resistant microorganisms are appearing at the forefront, significantly increasing the number of deaths. Innovative solutions must emerge to prevent the imminent health crisis risk, and antibacterial hydrogels are one of them. In addition to this, for the past ten years, photochemistry has become an appealing green process attracting continuous attention from scientists in the scope of sustainable development, as it exhibits many advantages over other methods used in polymer chemistry. Therefore, the combination of antimicrobial hydrogels and light has become a matter of course to design innovative antimicrobial materials. In the present review, we focus on the use of photochemistry to highlight two categories of hydrogels: (a) antibacterial hydrogels synthesized via a free-radical photochemical crosslinking process and (b) chemical hydrogels with light-triggered antibacterial properties. Numerous examples of these new types of hydrogels are described, and some notions of photochemistry are introduced

Light and Hydrogels: A New Generation of Antimicrobial Materials

Nosocomial diseases are becoming a scourge in hospitals worldwide, and new multidrug-resistant microorganisms are appearing at the forefront, significantly increasing the number of deaths. Innovative solutions must emerge to prevent the imminent health crisis risk, and antibacterial hydrogels are one of them. In addition to this, for the past ten years, photochemistry has become an appealing green process attracting continuous attention from scientists in the scope of sustainable development, as it exhibits many advantages over other methods used in polymer chemistry. Therefore, the combination of antimicrobial hydrogels and light has become a matter of course to design innovative antimicrobial materials. In the present review, we focus on the use of photochemistry to highlight two categories of hydrogels: (a) antibacterial hydrogels synthesized via a free-radical photochemical crosslinking process and (b) chemical hydrogels with light-triggered antibacterial properties. Numerous examples of these new types of hydrogels are described, and some notions of photochemistry are introduced

Matériaux sol-gel hybrides photopolymères synthétisés par voie radicalaire ou cationique (élaboration, mécanisme et applications)

L'étude concerne l'élaboration de matériaux hybrides par le procédé sol-gel et la photopolymérisation à partir de d'alcoxysilanes ayant une fonction polymérisable. Leur mise en oeuvre a consisté dans une première étape à former un réseau silicate à travers le procédé sol-gel puis à élaborer un réseau organique sous irradiation UV. Dans une première partie, nous avons démontré l'effet des alcoxydes de zirconium sur l'évolution du réseau inorganique et sur la photopolymérisation du 3-méthacryloxypropyltrimethoxysilane. Pour la première fois, il a été mis en évidence un mécanisme impliquant l'oxygène de l'air et les alcoxydes de zirconium, responsables de changements de propriétés de surface des films irradiés. Des expériences ont ensuite été investies dans l'étude de la photopolymérisation cationique de deux dérivés époxytrialcoxysilanes. A travers une méthodologie de synthèse en deux étapes, l'influence du réseau inorganique sur les photopolymérisations est dévoilée, mettant en avant le rôle néfaste de la densification du réseau inorganique sur les vitesses de polymérisation. Une analyse du matériau final en RMN du silicium et du carbone en phase solide a permis de souligner la capacité des acides de Bronsted, obtenus in situ à partir de la photolyse du photoamorceur, à promouvoir simultanément la polymérisation organique et inorganique du matériau. Dans le cadre d'une collaboration avec le National Center for Sensor Research à Dublin, nous avons finalement étudié la stabilité, en milieu sol-gel, de certains photoamorceurs radicalaires de type phosphine oxyde en présence d'alcoxydes de zirconium et optimiser les formulations impliquées dans la fabrication de guides d'onde.The synthesis of Hybrid Materials was investigated by both the sol-gel process and the photopolymerization of organosilanes containing a polymerizable group. Silicate and organic networks were builded up with the sol-gel process and through UV irradiation respectively. In a first part, the effect of zirconium alkoxides on the evolution of the inorganic network and the photopolymerization of 3-methacryloxypropyltrimethoxysilane was studied. For the first time, the unexpected rote of oxygen and zirconium alkoxides on the surface modification properties of the irradiated films has been demonstrated. A second study investigated the cationic photopolymerization of two epoxy-trimethoxysilanes resins synthesized through a preliminary sol-gel process. Following a traditional 2-step synthesis, the influence of the silicate network on photopolymerization kinetics was proved and the polymerization kinetics' slowdown within the silicate densification was demonstrated. A detailed analysis of the final material by 29Si and 13C solid state NMR spectroscopy underlined the capability of the Bronsted acids generated through photolytic degradation of the photoinitiator to simultaneously catalyze both epoxy ring-opening polymerization and alkoxysilane sol-gel polycondensation reactions. Finally, in a collaboration with the National Center for Sensor Research at Dublin, we studied the stability of phosphine oxide derived free-radical photoinitiators in sol-gel conditions with zirconium alkoxides and optimized the formulations involved in the waveguides fabrication.MULHOUSE-SCD Sciences (682242102) / SudocSudocFranceF

Electron Paramagnetic Resonance Spin Trapping (EPR–ST) Technique in Photopolymerization Processes

International audienceTo face economic issues of the last ten years, free-radical photopolymerization (FRP) has known an impressive enlightenment. Multiple performing photoinitiating systems have been designed to perform photopolymerizations in the visible or near infrared (NIR) range. To fully understand the photochemical mechanisms involved upon light activation and characterize the nature of radicals implied in FRP, electron paramagnetic resonance coupled to the spin trapping (EPR–ST) method represents one of the most valuable techniques. In this context, the principle of EPR–ST and its uses in free-radical photopolymerization are entirely described

Contributions of photochemistry to bio-based antibacterial polymer materials

International audienceSurgical site infections constitute a major health concern that may be addressed by conferring antibacterial properties to surgical tools and medical devices via functional coatings. Bio-sourced polymers are particularly well-suited to prepare such coatings as they are usually safe and can exhibit intrinsic antibacterial properties or serve as hosts for bactericidal agents. The goal of this Review is to highlight the unique contribution of photochemistry as a green and mild methodology for the development of such bio-based antibacterial materials. Photo-generation and photo-activation of bactericidal materials are illustrated. Recent efforts and current challenges to optimize the sustainability of the process, improve the safety of the materials and extend these strategies to 3D biomaterials are also emphasized

Enhancement of Biological Properties of Photoinduced Biobased Networks by Post-Functionalization with Antibacterial Molecule

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Antibacterial and antioxidant photoinitiated epoxy co-networks of resorcinol and eugenol derivatives

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An Efficient Thiol-Ene Chemistry for the Preparation of Amphiphilic PHA-Based Graft Copolymers

International audienceWe present a straightforward method to prepare amphiphilic graft copolymers consisting of hydrophobic poly(3-hydroxyalkanoates) (PHAs) backbone and hydrophilic a-amino-?-methoxy poly(oxyethylene-co-oxypropylene) (Jeffamine (R)) units. Poly(3-hydroxyoctanoate)-co-(3-hydroxyundecenoate) (PHOU) was first methanolyzed to obtain the desired molar mass. The amino end groups of Jeffamine were converted into thiol by a reaction with N-acetylhomocysteine thiolactone and subsequently photografted. This one-pot functionalization prevents from arduous and time-consuming functionalization of the hydrophilic precursor or tedious modifications of PHAs, thus simplifying the process. The amphiphilic nature of modified PHAs leads to water-soluble copolymers exhibiting thermoresponsive behavior

Co-Networks Poly(hydroxyalkanoates)-Terpenes to Enhance Antibacterial Properties

Biocompatible and biodegradable bacterial polyesters, poly(hydroxyalkanoates) (PHAs), were combined with linalool, a well-known monoterpene, extracted from spice plants to design novel antibacterial materials. Their chemical association by a photo-induced thiol-ene reaction provided materials having both high mechanical resistance and flexibility. The influence of the nature of the crosslinking agent and the weight ratio of linalool on the thermo-mechanical performances were carefully evaluated. The elongation at break increases from 7% for the native PHA to 40% for PHA–linalool co-networks using a tetrafunctional cross-linking agent. The materials highlighted tremendous anti-adherence properties against Escherichia coli and Staphylococcus aureus by increasing linalool ratios. A significant decrease in antibacterial adhesion of 63% and 82% was observed for E. coli and S. aureus, respectively