Synthesis and healing properties of poly(arylether sulfone)–poly(alkylthioether) multiblock copolymers containing disulfide bonds

Abstract

Thermoplastic elastomers composed of soft and hard segments are important elastic and processable synthetic polymers. The microphase-separated soft domains show low glass transition temperature and possess sufficient chain mobility at room temperature. In this study, we report the synthesis and healing properties of multiblock copolymers containing disulfide bonds as dynamic covalent bonds. The multiblock copolymers composed of poly(arylether sulfone) and poly(alkylthioether) segments were synthesized by oxidative coupling polymerization of the corresponding thiol-terminated oligomers. Atomic force microscopy phase images, differential scanning calorimetry, and dynamic mechanical analysis curves indicated the microphaseseparated morphology of the multiblock copolymer. Self-healing properties of the polymer were evaluated by changes in the elongation at break of the cut/adhered samples. The elongation recovery increased with UV irradiation time, and the multiblock copolymer showed a 93% recovery after UV irradiation for 5 h. The healing efficiency induced by UV irradiation, determined by subtracting the recovery without UV irradiation, was calculated to be 51%. According to the UV spectra and solubility changes after UV irradiation, the main healing factor in this study was the crosslinking reactions caused by thiyl radicals generated from UV irradiation instead of disulfide exchange reactions.

Synthesis and healing properties of poly(arylene ether sulfone)‐poly(alkyl disulfide) multiblock copolymers

“…Photo‐induced self‐healing polymers containing disulfide bonds were also reported in literatures . We recently reported self‐healable multiblock copolymers containing disulfide bonds . Since soft domains consist of flexible segments with low glass transition temperatures, they have moderate to high mobility at room temperature.…”

“…Triethylamine, potassium carbonate, cyclohexane, 5‐bromo‐1‐pentene, hydrazine monohydrate, and hydrogen peroxide (30% in water) were also purchased from Kanto Chemical Co., Inc. (Tokyo, Japan) and used without further purification. PES‐SH was synthesized from bis(4‐fluorophenyl) sulfone and 2,2’‐bis(4‐hydroxyphenyl)hexafluoropropane according to a previously described procedure . Chloroform (Shin‐Etsu Chemical, Tokyo, Japan), methanol (Daishin Chemical, Tokyo, Japan), and dichloromethane (AGC Ceramics Chemicals Company, Tokyo, Japan) were used without further purification.…”

“…Disulfide bonds are well‐known dynamic covalent bonds, and self‐healing materials containing these are described in the literature . Yoon et al reported autonomous self‐healing disulfide‐crosslinked star polymer gels .…”

“…18,19 Disulfide bonds are well-known dynamic covalent bonds, and self-healing materials containing these are described in the literature. [20][21][22][23][24][25][26][27][28][29][30][31] Yoon et al reported autonomous self-healing disulfide-crosslinked star polymer gels. 20 Lei et al reported autonomously self-healable cross-linked polysulfides in the presence of tri-n-butylphosphine as a catalyst.…”

“…29,30 We recently reported self-healable multiblock copolymers containing disulfide bonds. 31 Since soft domains consist of flexible segments with low glass transition temperatures, they have moderate to high mobility at room temperature. UV irradiation resulted in 93% recovery of the elongation at break of a cut sample.…”