Adrien Criqui

Continuous-flow synthesis of polymer nanoparticles in a microreactor via miniemulsion photopolymerization

An efficient continuous synthesis of nanolatex was achieved in water using a single-lane photochemical microreactor combined with an energy-saving and safe UV fluorescent lamp. Acrylate and thiol-ene miniemulsions were polymerized in high yields at low irradiance (3 mW cm−2) upon controlling droplet size, temperature and residence time.

Versatility of Pyrylium Salt/Vinyl Ether Initiating System for Epoxide Dual-Cure Polymerization: Kick-Starting Effect of the Coinitiator

Pyrylium salts combined with vinyl ethers are shown to act as new versatile dual-cure initiating systems for both photochemical and thermal initiation of oxirane monomers. The combination of both possibilities allows the curing of thick samples through photoinduced frontal polymerization. On the basis of quantum calculations and photochemical experiments, some clues are given about the reaction mechanisms involved. Interestingly, a sequential kick-starting effect is observed in the presence of vinyl ether enabling the curing of oxetane monomers. Thereby, this communication presents a short overview of potential of pyrylium salts in cationic polymerization of oxiranes.

Synthesis of acrylic latex via microflow miniemulsion photopolymerization using fluorescent and LED UV lamps

Abstract We show the potential of miniemulsion photopolymerization for the continuous production of aqueous poly(acrylate) dispersions in a microreactor at room temperature. While the starting acrylate nanoemulsions are amenable to limit scattering, their polymerization within a microreactor provides additionally small microchannels and short diffusion path enabling an efficient mixing in order to alleviate the constraints associated with non-uniform through-cure in turbid medium. Two key features prove that this process design is highly eco-efficient: i) two types of energy-saving and compact UV sources (fluorescent or light-emitting diode) were employed; ii) high conversions were achieved using the fluorescent lamp with short residence times (10 min), low irradiance (3 mW cm-2) and without the need of solvent. The present study describes briefly the influence of various parameters – flow rate, photo-initiator type/concentration, droplet size, solid content, UV source – on the photopolymerization course (kinetics) and the properties of the nanolatex obtained (particle size and molecular weight).

Stripping the latex: the challenge of miniemulsion polymerization without initiator, costabilizer and surfactant

When finally processed to provide the function for which the latex was selected―binding, protecting, finishing―components such as surfactant, costabilizer or initiator become generally useless, not to say detrimental. In this study, we show that miniemulsion photopolymerization provides a suitable method to create latex without the apparent addition of these three compounds. Indeed, UV-driven monomer self-initiation can create initiating radicals without the aid of initiator, the fast in situ photogenerated polymer can hinder Ostwald ripening with the assistance of external costabilizer, and finally, UV-transparent clay can replace conventional surfactant to ensure colloidal stabilization. Each strategy has been developed individually before being combined together to end up with a unique miniemulsion procedure free of initiator, costabilizer and surfactant. Such approach paves the way to a simplified and environmentally improved pathway towards aqueous polymer dispersions.