Highly Selective, Catalyst-Free, and Low Temperature Depolymerizable Styrene Copolymer With Incorporated α-Methylstyrene Structural Units

A simple strategy is proposed to offer styrene (St) copolymer with intrinsic and catalyst-free upcycling capability by incorporating alpha-methylstyrene (AMS) units into the copolymer poly(AMS-co-St) (PAS). Compared to polystyrene (PS), the PAS is more susceptible to depolymerizing into St and AMS monomers with higher yields at relatively lower temperature. The yield of liquid chemicals of PAS-4 (26.1 mol% AMS) is up to 93 wt% at 380 degrees C, whereas that PS as control is 78 wt%. The reclaimed liquid chemicals of PAS-4 contain 58.4 wt% St and 37.7 wt% AMS, while the chemicals of PS contain 81.8 wt% St and 4.1 wt% AMS. The introduction of AMS units in PAS leads to a reduction in the liquid chemicals other than St and AMS monomers. The blends of PS and PAMS do not demonstrate the synergistic effect regarding facilitating the PS depolymerization. In addition, the properties of the new PASs prepared with the reclaimed monomers are comparable with those of the virgin PASs. This work proves the concept that recycling efficiency could be boosted by incorporating liable structural units into the copolymer chains and demonstrates a closed-loop of PS up-cycling.