A Closed-Loop Recyclable Low-Density Polyethylene.

Low-density polyethylene (LDPE) is one of the most important plastics, which is produced unfortunately under extreme conditions. In addition, it consists of robust aliphatic C─C bonds which are challenging to cleave for plastic recycling. A low-pressure and -temperature (p = 2 bara, T = 70 °C) macromonomer-based synthesis of long chain branched polyethylene is reported. The introduction of recycle points permits the polymerization (grafting to) of the macromonomers to form the long chain branched polyethylene and its depolymerization (branch cleavage). Coordinative chain transfer polymerization employing ethylene and co-monomers is used for the synthesis of the macromonomers, permitting a high flexibility of their precise structure and efficient synthesis. The long chain branched polyethylene material matches key properties of low-density polyethylene.