Grafting Functional Groups onto Biodegradable Thermoplastic Polyesters

A general awareness of the environmental impacts of plastics has caused behavioral changes in the public sector. This in turn has led to research related to biodegradable or sustainable alternatives to petrochemical plastics. Biodegradable polymers have been around for years (e.g. poly(e-caprolactone) (PCL), poly(butylene succinate) (PBS) and poly(lactic acid) (PLA)). However, these have recently become an affordable alternative. PLA and poly(butylene adipate-co-terephthalate) (PBAT) are two polyesters that have gained significant research interest as biodegradable alternatives, especially for the preparation of natural or biobased polymer blends. Nonetheless, the lack of miscibility in some polymer blends limits their usefulness unless a compatibilizing agent is used. A very common strategy is to graft a functional monomer into the polymer backbone, of which maleic anhydride (MA) is the most common, but not the only one. This chapter explores the use of grafting functional groups onto polyesters in light of the well-established field of free radical grafting of polyolefins to achieve materials that are effective at compatibilizing biodegradable or compostable blends.