Visible‐Light Emulsion Photopolymerization of Styrene

Abstract

The photopolymerization of styrene in emulsion is achieved in ac onventional double-wall reactor equipped with aL ED ribbon coiled around the external glass wall. Styrene mixed to acridine orange is added to the water phase containing sodium dodecyl sulfate,awater-soluble N-heterocyclic carbene-borane and disulfide,a nd irradiated. Highly stable latexes are obtained, with particles up to ad iameter of 300 nm. The ability to reach such large particle sizes via ap hotochemical process in ad ispersed medium is due to the use of visible light:t he photons in the visible range are less scattered by larger objects and thus penetrate and initiate better the polymerizations.T hey are also greener and cheaper to produce via LEDs,a nd muchs afer than UVs.T he method presented does not require any specific glassware;i tw orks at lower temperature and delivers larger particles compared to thermal processes at similar solids contents and surfactant concentrations.

Visible-Light Emulsion Photopolymerization of Acrylates and Methacrylates: Mechanistic Insights and Introduction of a Simplified Sulfur-Based Photoinitiating System

“…As a follow-up to our previous work on visible light styrene emulsion photopolymerization, 18 we used our three-component system to investigate the MMA homo-photopolymerization in emulsion. The PIS (also referred as "full system") is a three-component system that includes acridine orange (AO) as sacrificial photo-single electron transfer reagent, the water-soluble triazolylidene-borane 1, 23 and aryl disulfide 2 (Figure 1).…”

“…This allowed us to produce polymer particles 4 with maximum diameter of 300 nm. 18 We now report the extension of our process to methyl methacrylate (MMA) and other (meth)acrylic monomer compositions. We show that (meth)acrylates are compatible with a simplified Sulfur-based PIS.…”

New horizons for carbon dots: quantum nano-photoinitiating catalysts for cationic photopolymerization and three-dimensional (3D) printing under visible light

“…67,68 In addition, this type of polymerization is highly tolerant to the presence of water in the system, which makes the radical photopolymerization reaction widely applicable on an industrial scale, not only using the classic method of polymerization, but also using the emulsification or suspension technique. [69][70][71] The use of various types of carbon dots for free-radical photopolymerization was first described by Jiang and others, 47 and they used carbon dots as photosensitizers in the RAFT (Reversible Addition-Fragmentation Chain Transfer) polymerization process. Later, Kutahya and others used carbon dots as a "green photocatalyst" in the radical polymerization process, using them in a photocatalytic system based on iodonium or sulphonium salt as a coinitator and carbon dots as a photosensitizer.…”

Photopolymerization in dispersed systems

“…The authors interpreted this result with photoinitiator end chain fragments (phenacyl groups) incorporated into the polymer backbone (as already mentioned above) generating upon electronic excitation new initiating radicals by hydrogen abstraction and called it a "snowballing radical generation" effect. Very recently, Lacôte and coworkers described the first use of visible light in emulsion photopolymerization using styrene as monomer and a photoinitiating system based on three different water-soluble compounds [120]. Although not studied, the mechanistic details may involve a first step of electron-transfer upon electronic excitation of a dye (acridine orange), leading to the photoreduction of a disulfide compound, further decomposed into thiyl radicals.…”