Selectively Controlled Ring-Opening Copolymerization to Chemically Recyclable Thermoplastic Elastomers

Abstract

The development of closed-loop recyclable thermoplastic elastomers (TPEs) represents a promising solution to address the serious plastic pollution. However, the traditional synthetic and chemical recycling pathways of triblock TPEs still face significant challenge due to their intrinsic complex multicomponent. Herein, we create a one-pot sequence-controlled copolymerization platform towards chemically recyclable TPEs. The distinct polymerization reactivity of aliphatic caprolactone-based monomer MTO and the benzo-fused or naphthalene-fused caprolactone-based monomer DHB or DHN allowed us to construct ABA triblock TPE products where the low-Tg PMTO segment served as the soft midblock and the high-Tm P(DHB) block or high-Tg P(DHN) block as the hard end segments. Remarkably, these resulting TPE products showcased tunable material properties by altering their compositions. TPE4 with FDHN = 0.21 demonstrated outstanding tensile strength, ductility, impressive toughness (UT = 133 ± 14 MJ/m 3 ), and high elastic recovery (>90%). More importantly, these synthesized TPE materials were able to depolymerize back to their monomers in presence of Sn(Oct)2 at 160-200 °C, establishing an efficient closed-loop recycling.