Waterborne polysulfide dispersions for coatings application.

309 p.Novel synthesis approach of high solids content film forming waterborne poly(thioethers), based on initiator-free step-growth sonopolymerization combined with photopolymerization in aqueous dispersed media is reported. With this process, ultra-high molar mass chains up to 200 kDa, the highest reported so far for step grown poly(thioethers) The crystallization of as-synthesized poly(thioethers) was studied by implementing a self-nucleation (SN) procedure in this polymer type, which take the advantage of the presence of a previous crystalline state memory that persists the melting process to boosts the re-crystallization kinetics. Crystallization studies were also implemented in poly(thioethers) with various chemical structures. Finally, we report the synthesis of film forming poly(thioethers) containing newly synthesized biobased monomers

Unraveling the complex polymorphic crystallization behavior of the alternating copolymer DMDS-alt-DVE

[Abstract]: A complex crystallization behavior was observe the alternating copolymer DMDS-alt-step-growth polymerization. Understanding the underlying complex crystallization processes of such innovative polythioethers is critical for their application, for example, in polymer coating technologies. These alternating copolymers have polymorphic traits, resulting in different phases that may display distinct crystalline structures. The copolymer DMDS-alt-DVE was studied in an earlier work, where only two crystalline phases were reported: a low melting, L − Tm, and high melting, H − Tm phase. Remarkably, the H − Tm form was only achieved by the previous formation and melting of the L − Tm form. We applied calorimetric techniques encompassing seven orders of magnitude in scanning rates to further explore this complex polymorphic behavior. Most importantly, by rapidly quenching the sample to temperatures well below room temperature, we detected an additional polymorphic form (characterized by a very low melting phase, denoted VL − Tm). Moreover, through tailored thermal protocols, we successfully produced samples containing only one, two, or all three polymorphs, providing insights into their interrelationships. Understanding polymorphism, crystallization, and esulting morphological differences can have significant implications and potential impact on mechanical resistance and barrier roperties.Gobierno Vasco; IT1503-22Gobierno Vasco; IT-1525-22Ministerio de Ciencia e Innovación; PGC2018-094620-A-I00Xunta de Galicia; ED431F 2021/00

Semi‐Crystalline Poly(thioether) Prepared by Visible‐Light‐Induced Organocatalyzed Thiol‐ene Polymerization in Emulsion

International audienceA 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