Photodisulfidation of alkenes with linear disulfides: Reaction scope and kinetics

Kamps, Joshua T.; Soars, Shafer M.; Bongiardina, Nichloas J.; Fairbanks, Benjamin D.; Bowman, Christopher N.

doi:10.1016/j.tet.2022.132683

Cited by 6 publications

(15 citation statements)

References 20 publications

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Section: Resultsmentioning

confidence: 99%

“…This outcome differs from the small molecule studies performed by Kamps et al , where the mercaptopropionate disulfide reacted approximately 10 times slower than the thioglycolate disulfide. 14 Nevertheless, the fact that the disulfide–ene rate with DMP is comparable to DTG indicates that the scope of linear disulfides that can be effectively copolymerized with thiols is not limited by their reaction rates in model reactions. In addition, the relative rate of thiol–ene polymerization for each thiol monomer aligns with the relative rates observed in the control thiol–ene reactions at the same 1 : 2 ratio of thiol to alkene as found in Table 2: PETTG was the fastest, then PETMP, then SiTSH.…”

Section: Resultsmentioning

confidence: 99%

“…As expected, reacting the excess thiols with BVE resulted in slower stress relaxation compared to when free thiols were present for both thiol monomers, but this effect was more pronounced for PETTG than PETMP. This result is not surprising because kinetic analysis indicates that little productive bond exchange occurs between mercaptopropionate radicals and thioglycolate disulfides, 14 meaning excess thiols should impact relaxation more for PETTG than PETMP. Interestingly, the PETMP networks relaxed stress far more rapidly than PETTG both with and without BVE though they only differ in their molecular weight between crosslinks.…”

Section: Impact Of Structure and Functional Groups On Stress Relaxationmentioning

confidence: 98%

“…The disulfide monomer, DTG, was chosen because of the relatively high reaction rates of its disulfide with vinyl ethers. 14 In addition, DTG can be effectively copolymerized with PETMP, which is a widely used and commercially available multifunctional thiol. Polymerization proceeds, beginning with a monomer resin mixture to form a primarily thiol-ene stage 1 network made up of thioether bonds, then through the disulfide-ene reaction to form the thioacetal bonds in the stage 2 network.…”

Section: Radical-mediated Stress Relaxationmentioning

confidence: 99%

“…aromatic disulfide-containing polyurethane networks, 8,11 photoadaptable hydrogels, 10 and epoxy resins. 12 Recently, however, a variety of disulfides have been investigated for their participation in disulfide-ene reactions in which the disulfide reacts with norbornenes 13 or vinyl ethers 14 via a step growth mechanism analogous to the thiol-ene reaction. Disulfide-ene reactions with cyclic, 15,16 and certain linear disulfides, 14,17 are efficient crosslinking chemistries that generate thioacetal linkages rather than the thioethers associated with thiol-ene, doubling the number of bonds formed per alkene.…”

Section: Introductionmentioning

confidence: 99%

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Radical-disulfide exchange in thiol–ene–disulfidation polymerizations

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Impact Of Structure and Functional Groups On Stress Relaxationmentioning

confidence: 98%

Section: Radical-mediated Stress Relaxationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Radical-disulfide exchange in thiol–ene–disulfidation polymerizations

et al. 2022

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Photoinduced Dithiolane Crosslinking for Multiresponsive Dynamic Hydrogels

et al. 2023

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While many hydrogels are elastic networks crosslinked by covalent bonds, viscoelastic hydrogels with adaptable crosslinks are increasingly being developed to better recapitulate time and position‐dependent processes found in many tissues. In this work, 1,2‐dithiolanes are presented as dynamic covalent photocrosslinkers of hydrogels, resulting in disulfide bonds throughout the hydrogel that respond to multiple stimuli. Using lipoic acid as a model dithiolane, disulfide crosslinks are formed under physiological conditions, enabling cell encapsulation via an initiator‐free light‐induced dithiolane ring‐opening photopolymerization. The resulting hydrogels allow for multiple photoinduced dynamic responses including stress relaxation, stiffening, softening, and network functionalization using a single chemistry, which can be supplemented by permanent reaction with alkenes to further control network properties and connectivity using irreversible thioether crosslinks. Moreover, complementary photochemical approaches are used to achieve rapid and complete sample degradation via radical scission and post‐gelation network stiffening when irradiated in the presence of reactive gel precursor. The results herein demonstrate the versatility of this material chemistry to study and direct 2D and 3D cell‐material interactions. This work highlights dithiolane‐based hydrogel photocrosslinking as a robust method for generating adaptable hydrogels with a range of biologically relevant mechanical and chemical properties that are varied on demand.

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Exploring the effect of dynamic bond placement in liquid crystal elastomers

Lindberg,

Ghimire,

Chen

et al. 2023

Journal of Polymer Science

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Dynamic liquid crystal elastomers (LCEs) are a class of polymer networks characterized by the inclusion of both liquid crystalline monomers and dynamic covalent bonds. The unique properties realized through the combination of these moieties has produced a plethora of stimuli‐responsive materials to address a range of emerging technologies. While previous works have studied the incorporation of different dynamic bonds in LCEs, few (if any) have studied the effect of the specific placement of the dynamic bonds within an LCE network. A series of dynamic LCE networks were synthesized using a generalizable approach that employs a tandem thiol‐ene/yne chemistry which allows the location of the dynamic disulfide bond to be varied while maintaining similar network characteristics. When probing these systems in the LC regime, the thermomechanical properties were found to be largely similar. It is not until elevated temperatures (160–180 °C) that differences in the relaxation activation energies of these systems begin to materialize based solely on differences in placement of the dynamic bond throughout the network. This work demonstrates that through intentional dynamic bond placement, stress relaxation times can be tuned without affecting the LCE character. This insight can help optimize future dynamic LCE designs and achieve shorter processing times.

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Photodisulfidation of alkenes with linear disulfides: Reaction scope and kinetics

Cited by 6 publications

References 20 publications

Radical-disulfide exchange in thiol–ene–disulfidation polymerizations

Radical-disulfide exchange in thiol–ene–disulfidation polymerizations

Photoinduced Dithiolane Crosslinking for Multiresponsive Dynamic Hydrogels

Exploring the effect of dynamic bond placement in liquid crystal elastomers

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