Branched Polytetrahydrofuran and Poly(tetrahydrofuran-co-ε-caprolactone) Synthesized by Janus Polymerization: A Novel Self-Healing Material

The Janus polymerization combines cationic and anionic polymerizations into growing chains with two different chain ends. This provides a novel pathway to produce topologically interesting polymers. Here this polymerization is applied to allow the synthesis of branched polytetrahydrofuran (bPTHF) and poly(tetrahydrofuran-co-epsilon-caprolactone) (bPTC). Rare earth triflates [RE(OTf)(3)] (RE = Lu, Sc, and Y) are used as catalyst, and small amounts (0.10-0.15 mol%) of ethylene glycol diglycidyl ether act as both initiator and comonomer due to the different reactivities of the two epoxide groups. The poly(epsilon-caprolactone) block in bPTC provides crystalline domains and potential degradation under acidic conditions. The products of bPTHF show unusual tensile properties with a high strain at break of 1070% differing greatly from linear PTHF. Due to the large number of terminal hydroxyl groups and their strong hydrogen bonding, bPTHF has self-healing properties with potentially promising applications.