Cationic ring-opening polymerization of natural thioctic acid to chemically recyclable and self-healable poly(thioctic acid) supramolecular material

Poly(disulfide) with dynamically reversible disulfide bonds in backbone is a kind of sustainable polymer materials. Poly(thioctic acid) (PTA) synthesized via ring-opening polymerization (ROP) of natural thioctic acid (TA) is one of typical poly(disulfide)s with self-healing and adhesion properties due to abundant carboxyls in side chains. However, the quantificational ROP of TA has not been achieved based on the methods reported so far. The synthesis of PTA with targetable molecular weight by the cationic ROP (CROP) of TA was reported here. The molecular weight of PTA can be conveniently designed by the molar ratio of TA monomer to trifluoromethanesulfonic acid (TfOH) initiator, and the properties of PTA can be regulated in this way. Moreover, the CROP of TA allows open-air conditions without inert protection. The closed-loop recycling of PTA can be achieved in the action of base and acid with high TA monomer recovery ratio up to 86.0% and 89.0%, respectively. PTA could be completely self-healing at 25°C or 80°C within 6 min after cutting on its surface. Our results demonstrate the possibility of applying this convenient CROP strategy for the synthesis of PTA with targetable molecular weights, controllable properties and application prospect.