Radical-disulfide exchange in thiol–ene–disulfidation polymerizations

Abstract

The influence of radical-disulfide exchange on the polymerization and relaxation dynamics of thiol–ene–disulfide networks is investigated.

Thiol–Ene Networks with Tunable Dynamicity for Covalent Adaptation

“…To ensure our cured materials are exclusively thiol–ene polymers, we use stoichiometric mixtures of our thiol and allyl components and thus avoid any subsequent disulfide-ene reaction, which would change the network structure drastically . The materials are simply coded as DAG x , where x denotes the weight percent of the disulfide-containing DAG monomer, so that the weight percent of the disulfide-free allyl monomer TATATO is (100 – x ).…”

Adaptable Networks with Semiorthogonal Two-Stage Polymerizations Enabled by Sequential Photoinitiated Thiol–Ene and Disulfide–Ene Reactions

“…During the second-stage disulfide–ene reaction, every disulfide moiety reacts with a double bond to form two additional thioether cross-links. Meanwhile, the cleavage of disulfide bonds accompanying the disulfide–ene addition relieves the deformation stress . As such, the thiol–ene disulfidation system described herein is a perfect match for these requirements.…”

“…Meanwhile, the cleavage of disulfide bonds accompanying the disulfide−ene addition relieves the deformation stress. 27 As such, the thiol−ene disulfidation system described herein is a perfect match for these requirements. As with the photolithography experiments, the first-stage thiol−ene photopolymerization of DSDVE and PETMP generated a transparent elastomeric film (Figure 2d).…”

“…Furthermore, two-stage materials containing disulfides in the backbone of their initial network are able to relax stress to some degree during the second-stage polymerization. 27,28 The stress relaxation during the second stage is beneficial for more efficient second-stage hologram formation and more homogeneous final networks when compared to typical two-stage systems without such dynamic properties. 29,30 In this work, dynamic two-stage photopolymer systems are demonstrated utilizing monomers compatible with both thiol− ene and disulfide−ene chemistries (Scheme 1c) to enable applications in reshapable materials, lithography, and holography.…”

Optimization and Testing of Hybrid 3D Printing Vitrimer Resins

“…The use of vitrimers in the realm of 3D-printing is somewhat new. Intended mostly for sterolithographic applications, such as digital light processing (DLP) printing, photosensitive resins are formulated from vitrimeric monomers that feature the aforementioned dynamic bonds based on chemistries such as disulfides [ 16 , 17 ] or esters [ 18 , 19 ] that can undergo bond exchange reactions when heated. These exchange reactions enable the repair and reprocessing of printed parts, using simple welding or hot pressing procedures.…”