Influence of Glass Transition Temperature on Mechanical and Self-Healing Behavior of Polymers Bearing Hindered Urea Bonds

摘要

Considerable interest has been placed on polymers which can intrinsically self-heal. Numerous studies have shown that polymer networks bearing dynamic covalent bonds exhibit the ability to self-repair. The focus of this paper is to describe the synthesis and characterization of polymer networks of varying rigidity bearing hindered urea bonds (HUB) based on 1-(tert-butyl)-1-ethylurea (TBEU). Results indicate that the partial substitution of Hexamethylene Diisocyanate (HMDI) with an aromatic diisocyanate (m-Xylylene Diisocyanate, XDI) results in a predictable increase in Tg and a corresponding increase in both modulus and tensile strength at break. Furthermore, polymers containing up to 50mol% XDI were shown to self-heal, though the efficacy decreases with increasing XDI content at constant healing conditions (60°C/12 hours).