Synthesis and depolymerization loop of ester-linked chemically recyclable polypropylene | Poster Board #M38

One of the most produced polymer materials, and the majority (~65%) of the thermoplastic polymer materials in use are polyolefins (POs). Based on 2012, only 16.2% of POs are recycled. To this end, we have developed a methodological loop to synthesize and depolymerize polypropylene-based ester-linked POs. As a starting unit, we used commercially available maleic anhydride-modified low molecular weight (Mn~3,900 g/mol) isotactic polypropylene. The first-generation ester-linked PO containing covalent adaptable networks was synthesized via an epoxy ring opening reaction using 1,4-Butanediol diglycidyl ether as a chain cross-linker and ZnCl₂ as a Lewis catalyst. We obtained the PO material having flexural modulus and stress at 5% strain values between LDPE and HDPE (490MPa and 16MPa, respectively). Next, a transesterification reaction was conducted to depolymerize ester-linked POs using monofunctional alcohol − 1-pentanol. Finally, we synthesized a second-generation recycled PO with flexural modulus and stress at 5% strain of 390MPa and 13MPa, respectively.