Thermoreversibly crosslinked poly(ε-caprolactone) as recyclable shape-memory polymer network

摘要

A new concept to build shape memory polymers (SMP) combining outstanding fixity and recovery ratios (both above 99% after only one training cycle) typical of chemically crosslinked SMPs with reprocessability restricted to physically crosslinked SMPs is demonstrated by covalently bonding, through thermoreversible Diels-Alder (DA) adducts, star-shaped poly(ε- caprolactones) (PCL) end-functionalized by furan and maleimide moieties. A PCL network is easily prepared by melt-blending complementary end-functional star polymers in retro DA regime, then by curing at lower temperature to favour the DA cycloaddition. Such covalent network can be reprocessed when heated again at the retro DA temperature. The resulting SMP shows still excellent shape memory properties attesting for its good recyclability. Covalently crosslinked still recyclable shape memory polymers (SMP) are prepared using thermoreversible Diels-Alder adducts. Excellent fixity and recovery ratios, obtained after only one training cycle, are measured both for the initial and the recycled SMPs.