Semi‐Crystalline Poly(thioether) Prepared by Visible‐Light‐Induced Organocatalyzed Thiol‐ene Polymerization in Emulsion. Issue 5 (23rd December 2021)

• Record Type: Journal Article
• Authors: Le, Cuong Minh Quoc; Schrodj, Gautier; Ndao, Ibrahima; Bessif, Brahim; Heck, Barbara; Pfohl, Thomas; Reiter, Günter; Elgoyhen, Justine; Tomovska, Radmila; Chemtob, Abraham
• Is Part Of: Macromolecular rapid communications. Volume 43:Issue 5(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-12-23
• Subjects: emulsion polymerization -- photocatalysis -- semicrystalline polymers -- visible‐light; Macromolecules -- Periodicals; Polymers -- Periodicals; Chemistry -- Periodicals; 547.705
• DOI: 10.1002/marc.202100740
• Languages: English
• ISSNs: 1022-1336

Abstract

Abstract: A photocatalytic thiol‐ene aqueous emulsion polymerization under visible‐light is described to prepare linear semicrystalline latexes using 2, 2'‐dimercaptodiethyl sulfide as dithiol and various dienes. The procedure involves low irradiance (3 mW cm −2 ), LED irradiation source, eosin‐Y disodium as organocatalyst, low catalyst loading (<0.05% mol), and short reaction time scales (<1 h). The resulting latexes have molecular weights of about 10 kg mol −1, average diameters of 100 nm, and a linear structure consisting only of thioether repeating units. Electron‐transfer reaction from a thiol to the triplet excited state of the photocatalyst is suggested as the primary step of the mechanism (type I), whereas oxidation by singlet oxygen generated by energy transfer has a negligible effect (type II). Only polymers prepared with aliphatic dienes such as diallyl adipate or di(ethylene glycol) divinyl ether exhibit a high crystallization tendency as revealed by differential scanning calorimetry, polarized optical microscopy, and X‐ray diffraction. Ordering and crystallization are driven by molecular packing of poly(thioether) chains combining structural regularity, compactness, and flexibility. Abstract : By leveraging advances in photoredox catalysis, an industrially relevant photocatalyzed thiol‐ene polymerization in emulsion is designed. High monomer conversions are achieved at low catalyst loading and low irradiance. Highly crystalline poly(thioether)s are obtained by careful selection of monomers favouring chain linearity and compactness. Crystallinity is a very unusual property for a polymer prepared in water.