Tunable Surfaces and Films from Thioester Containing Microparticles

Abstract

Reported here, thioester containing microparticles were designed with 40% excess thiol to enable thiol–thioester exchange to facilitate the formation of cohesive films from the particles. A thiol-Michael dispersion polymerization was used to generate thioester containing microparticles with a diameter of 4.0 ± 0.4 μm. The particles were then swollen with a base at varying concentrations to activate the thiol–thioester exchange and subsequently compressed between two glass slides. Resultant films were characterized over time with profilometry and atomic force microscopy (AFM) to infer particle coalescence at different catalyst loadings and times. Tensile tests were performed confirming the structural integrity of the particle-based films. Furthermore, microparticles were welded to a nondynamic network demonstrating feasibility in potential applications to generate materials containing differing mechanical properties. Being able to control the functionality of particles, and thus mechanical properties of the resultant films, is also important for applications in coatings, adhesives, and 3D printing where spatial patterning or selective material property control is needed.

On the Welding of Vitrimers: Chemistry, Mechanics and Applications

“…[ 109 ] Mimicking the transesterification (Table 1A), thiol‐thiolester exchange (Table 2F) can be catalyzed by a triethylamine base, which was used to fabricate vitrimer films via the thiol solvent aided welding of thioester‐featured vitrimer particles. [ 110 ] Inspired by the dynamic exchange of thiol‐Michael adducts (Table 1K), a derivative of the thiol‐Michael reaction (Table 2G) was developed to fabricate silicone vitrimers, [ 111 ] which can be repeatedly welded up to 10 cycles without significant loss of their mechanical properties. Surprisingly, these two thiol‐Michael reactions (Table 1K and Table 2G) will not being dissociated at elevated temperature, which inevitably occurs for those conventional thiol‐Michael reactions leading to the abrupt dissolution of crosslinked polymers and losing the vitrimer properties.…”

Stress‐Induced Shape‐Shifting Materials Possessing Autonomous Self‐Healing and Scratch‐Resistant Ability

“…Typically the thio‐ene systems are light responsive and the resulting CANs exhibit stress relaxation ability in presence of light as stimuli [64] . In case of thia Michael adducts, the equilibrium with acrylate accepters is tilted towards the forward direction and typically favours the adducts [65,66] . Interestingly, the Michael acceptors may be activated to induce swift reversibility to the addition reaction.…”

“…[64] In case of thia Michael adducts, the equilibrium with acrylate accepters is tilted towards the forward direction and typically favours the adducts. [65,66] Interestingly, the Michael acceptors may be activated to induce swift reversibility to the addition reaction. For example, thia Michael addition of 1,1-bis-electron withdrawal group (EWG) substituted double bonds with thiol displayed swift reversibility and the equilibrium was strongly dependent on the concentration of the reacting species.…”