• Katashima, Takuya
• Sakai, Takamasa
• Law, Simon Sau Yin
• Terada, Kayo
• Masunaga, Hiroyasu
• Tsuchiya, Kousuke
• Tsuji, Yui
• Numata, Keiji

Abstract

<jats:title>Abstract</jats:title><jats:p>Covalently cross-linked rubber materials are widely used in elastic applications due to their excellent mechanical properties. However, the irreversibility of covalent cross-linking suffers from poor material recyclability. As a degradable polypeptide-based cross-linker for polybutadiene, poly(<jats:sc>l</jats:sc>-cysteine) (polyCys) was synthesized via papain-catalyzed chemoenzymatic polymerization. The resulting polyCys had intact thiol groups that cross-linked polybutadiene via the thiol-ene reaction. The cross-linking reaction of polybutadiene was performed in the presence of polyCys and a radical initiator and resulted in insoluble polybutadiene gel formation. Based on Raman spectroscopy analysis, the cross-linking reaction was confirmed by the consumption of thiol groups of polyCys. From the dynamic viscoelastic analyses of the cross-linked polybutadienes, the viscoelasticity drastically changed from that of raw polybutadiene, with the disappearance of the slow relaxation mode at low frequencies. The complete network formation was confirmed by <jats:italic>E</jats:italic>′ and <jats:italic>E</jats:italic>′′ showing the power law over the whole frequency range, as determined by the time-course experiments of the dynamic viscoelastic properties. The cross-linked polybutadiene was degradable by acid hydrolysis, resulting in the regeneration of soluble polybutadiene. Polypeptide cross-linked polybutadiene materials are promising candidates for the application of polybutadiene-based rubber materials with the requirements of both material integrity and reusability.</jats:p>

Topics

• experiment
• viscoelasticity
• Raman spectroscopy
• rubber