The Synthesis of Self-healable Elastomers with Heterocyclic Isosorbide Oligomers for the Enhanced Mechanical Properties

Abstract

A new heterocyclic elastomer based on isosorbide oligomer (HEIO) is synthesized and its self-healing and mechanical properties are characterized in this study. First, an isosorbide oligomer (ISBO) with hydroxyl groups at the ends is synthesized by reacting isosorbide (ISB) and isophorone diisocyanate (IPDI). To synthesize HEIO, the blend of polyol and ISBO is reacted with crosslinker containing multiple isocyanate groups (Xlinker). To compare the self-healing and mechanical properties, polyol is reacted with Xlinker to prepare conventional elastomer (CE) and the blend of polyol and ISB is reacted with the blend of Xlinker and IPDI to prepare heterocyclic elastomer with randomly distributed isosorbide moieties (HEI). Interestingly, HEIO exhibits outstanding self-healing efficiency (95%) compared to CE (7%) and HEI (30%). HEIO has high transmittance (91%), low haze (0.23) and yellow index (1.61), which proves that it suitable for coating applications. As a result of mechanical bulk and surface properties, HEIO shows enhanced tensile strength (31.9 MPa), young’s modulus (800.5 MPa), and surface hardness (100.85 MPa). The result is due to the strong hydrogen bonding interaction between urethane and ISBO, and we analyze this result through modeling system of FT-IR spectroscopy. In addition, to evaluate whether the elastomer of this study is suitable as a flexible display material, the film was repeatedly rolled and folded. As a result, the HEIO filme was not broken and the optical properties of HEIO were maintained. Therefore, HEIO can be widely applied in fiexible display industries and various coating industries. As a result, the problem caused by external stimuli (pressing, tearing) of the display material was overcome by introducing a self-healable elastomer. The trade-off effect was overcome by introducing a new oligomer synthesis method based on isosorbide to the conventional elastomer. In addition, since HEIO withstands repetitive physical deformation without external damage, the possibility of application as a flexible display material was also derived.