Novel Thermally-Reversible Epoxy-Urethane Networks

Abstract

Thermally-reversible epoxy-urethane networks are prepared by the reaction of diamines and diepoxy monomers containing two Diels–Alder adducts. The diepoxy compounds are formed via a Diels–Alder reaction between two epoxy-containing furans and bismaleimides having urethane moieties. The urethanebismaleimides were obtained by the reaction of 4-maleimidophenylisocyanate with poly(tetrahydrofuran) diols with M n = 650, 1000 and 1450. The epoxy-urethane networks display two glass transition temperatures in the range of –70 and –50°C for the soft segment and 81–84°C for the hard segment. At temperatures exceeding 116°C the retro Diels–Alder reaction occurs, which leads to a significant loss in modulus.