Molecular dynamics interpretation of hydrogen bonds for colorless, water-resistant, tough, and self-healable elastomers

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2023-10, Vol.11 (42), p.22737-22748
• Main Authors: Kim, Seon-Mi, Lee, Minkyung, Park, Sanggil, Park, Seul-A, Jeon, Hyeonyeol, Koo, Jun Mo, Park, Sung Bae, Kim, Hyo Jeong, Eom, Youngho, Lee, Eun Seong, Kim, Hyungjun, Oh, Dongyeop X, Park, Jeyoung
• Format: Article
• Language: English
• Subjects: Ambient temperature; Chromophores; Commercialization; Covalent bonds; Crosslinking; Elastomers; Hydrogen bonding; Hydrogen bonds; Molecular dynamics; Protective coatings; Substrates; System effectiveness; Tensile strength; Urethane thermoplastic elastomers; Water resistance
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d3ta03811d

Transparent, self-healing elastomers play a vital role as protective coatings, particularly in display applications. However, mechanical toughness and efficient self-restoration are often mutually exclusive. A performance equilibrium can be achieved through the molecular design of reversible bonds. However, aromatic disulfide-based dynamic covalent bonds produce an unattractive coloration owing to electron chromophores. In addition, H-bond moieties induce unintended adhesion to the substrates and are limited by hydration-induced weakening. In this study, the molecular design of aliphatic disulfides is presented for colorless, non-tacky, and water-resistant elastomers that rapidly self-heal at ambient temperatures. By employing molecular dynamics simulations, we demonstrate that an excess of H-bond acceptors promotes shorter bond exchange durations while maintaining a higher quantity of cohesive H-bonds, surpassing the performance of equivalent donor/acceptor systems at identical donor concentrations. In addition, dynamic H-bond exchange enables effective healing, whereas the increased H-bond cross-linking density ensures both waterproofness and an impressive tensile strength of 45 MPa. Furthermore, the absence of aromatic groups grants the elastomers a remarkable transmittance of 99%. The optimized properties achieved in this study using the proposed strategic molecular designs will further the commercialization of self-healing thermoplastic polyurethanes as intelligent protective coatings. A new molecular dynamics for transparent and self-healing elastomers are developed that uses aliphatic disulfide and H-bond acceptors to produce colorless and waterproof coatings, particularly in display applications.