Nanoconfinement in miniemulsion increases reaction rates of thiol–ene photopolymerization and yields high molecular weight polymers

Teixeira, Lorena Infante; Landfester, Katharina; Thérien-Aubin, Héloı̈se

doi:10.1039/d2py00350c

Cited by 6 publications

(4 citation statements)

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“…In chain polymerization, it is generally accepted that the MW of chain polymers is an order of magnitude greater than that in a similar homogeneous free‐radical polymerization due to segregation of propagating chains in small particles 1 . Our assumption is that similar compartmentalization effect may also take place in a radical step thiol‐ene polymerization as evidenced in a recent study carried out in miniemulsion polymerization 29 . Another interesting observation is the gradual broadening of the MW distribution in the course of the reaction.…”

Section: Resultsmentioning

confidence: 61%

Thiol‐ene emulsion step polymerization in a photochemical stirred tank reactor: Molecular weight, cyclization, and fragmentation

Chemtob

2022

Journal of Polymer Science

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Unlike many step polymerizations, the polymerization of bifunctional thiol and alkene monomers can be carried in emulsion to prepare a range of sulfur‐containing polymer particles differing markedly from conventional emulsion chain polymers. This study examines how the change of polymerization mechanism affects polymer molecular weight, structure and composition. A 2,2′‐dimercaptodiethyl sulfide/diallyl phthalate emulsion is photopolymerized in a photochemical stirred‐tank reactor equipped with Light‐emitting diodes (LEDs) to yield a 30% solids content latex with a high weight‐average molecular weight (100 kDa) and a broad molecular weight distribution (Đ = 8.5). Intramolecular cyclization occurs during polymerization by the addition of a thiyl radical to the unsaturated end group of the same molecule. Irreversible ring‐closure takes place to produce “dead” cyclic oligomers in the early stage of the reaction, whereas chain‐growth continues at high conversion. Consequently, the particles are composed of high molecular weight linear chains and a fraction of stable oligomer cycles, showing a broad and bimodal molecular weight distribution. The linear poly(thioether) chains include occasionally disulfide units due to thiyl radical recombination. The reversibility of disulfide bonds causes a decrease of molecular weight during storage. The addition of radical inhibitor to the latex stops fragmentation of SS bonds.

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Section: Resultsmentioning

confidence: 61%

Thiol‐ene emulsion step polymerization in a photochemical stirred tank reactor: Molecular weight, cyclization, and fragmentation

Chemtob

2022

Journal of Polymer Science

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“…These results indicate that after sonopolymerization, the prepolymers based on the EDDT–DATP pair are still bifunctional. In the literature, the number-average molecular weight ( M n ) reported for poly(thioethers) containing EDDT monomers synthesized in miniemulsion are in a range of 20 and 55 kDa with the DAA 9 or DAP 8 dienes. Hence, the combination of sonopolymerization and photopolymerization turns out to be an efficient tool for producing particularly high molar mass step growth polymers.…”

Section: Resultsmentioning

confidence: 99%

“…The feasibility of thiol–ene photopolymerization in aqueous dispersed media is well documented in the literature and has been performed in emulsion, , miniemulsion, − and suspension, giving rise to linear or cross-linked poly(thioether) dispersions in water, also called latexes. Among these processes, thiol–ene polymerization in miniemulsion is a privileged means to obtain high sulfur-content products with controlled colloidal properties and architecture.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Crystallization of Waterborne Thiol–ene Polymers: Toward Innovative Oxygen Barrier Coatings

Elgoyhen,

Pirela,

Müller

et al. 2023

ACS Appl. Polym. Mater.

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The synthesis of waterborne thiol–ene polymer dispersions is challenging due to the high reactivity of thiol monomers and the premature thiol–ene polymerization that leads to high irreproducibility. By turning this challenge into an advantage, a synthesis approach of high solid content film-forming waterborne poly(thioether) prepolymers is reported based on initiator-free step growth sonopolymerization. Copolymerization of bifunctional thiol and ene monomers diallyl terephthalate, glycol dimercaptoacetate, glycol dimercaptopropionate, and 2,2-(ethylenedioxy)diethanethiol gave rise to linear poly(thioether) functional chains with molar mass ranging between 7 and 23 kDa when synthesized at 30% solid content and between 1 and 9 kDa at increased solid content of 50%. To further increase the polymers’ molar mass, an additional photopolymerization step was performed in the presence of a water-soluble photoinitiator, i.e., lithium phenyl-2,4,6-trimethylbenzoylphosphinate, leading to high molar mass chains of up to 200 kDa, the highest reported so far for step grown poly(thioethers). The polymer dispersions presented good film-forming ability at room temperature, yielding semicrystalline films with a high potential for barrier coating applications. Nevertheless, affected by the polymer chemical repeating structure, which includes an aromatic ring, these thiol–ene chains can only crystallize very slowly from the molten state. Herein, for the first time, we present the successful implementation of a self-nucleation (SN) procedure for these types of poly(thioethers), which effectively accelerates their crystallization kinetics.

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“…The effect of the nanoconfinement on molecular mass of polymers prepared in miniemulsion has been well documented for other types of polymerization such as radical polymerization, 32 or thiol-ene addition. 33 The results suggest that the compartmentalization of the reaction also affects the inverse-vulcanization. Similar M n were obtained when varying the monomer feed composition from a S 8 content of 33 to 87 mol% (50 to 94 wt%) (Fig.…”

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confidence: 95%

Sulfur-rich polymer nanoparticles prepared by miniemulsion polymerization

et al. 2022

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Nanoconfinement in miniemulsion increases reaction rates of thiol–ene photopolymerization and yields high molecular weight polymers

Abstract: Thiol-ene polymerization is a powerful synthetic platform for the preparation of a variety of polymer materials but is often plagued by the formation of low molecular weight polymers. This is...

Cited by 6 publications

References 58 publications

Thiol‐ene emulsion step polymerization in a photochemical stirred tank reactor: Molecular weight, cyclization, and fragmentation

Thiol‐ene emulsion step polymerization in a photochemical stirred tank reactor: Molecular weight, cyclization, and fragmentation

Synthesis and Crystallization of Waterborne Thiol–ene Polymers: Toward Innovative Oxygen Barrier Coatings

Sulfur-rich polymer nanoparticles prepared by miniemulsion polymerization

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