Polyester transesterification through reactive blending and its applications: a comprehensive review

Transesterification through reactive blending provides a simple, solventless, and versatile reaction for creating copolymers between polyesters and polycarbonate blends adaptable to diverse applications. However, controlling transesterification to tailor properties has proven challenging due to the complex interconnected parameters influencing the process. This review provides a comprehensive analysis, covering topics from reaction mechanisms to applications, to reveal critical parameters in governing transesterification and establishing a framework for controlling transesterification to suit commercial needs. Our analysis has found that catalyst-related parameters such as composition, loading and solubility emerge as the most critical factors in controlling the transesterification rate. Blend compositions also play an important role, which can independently influence both transesterification efficiency and materials properties through its impact on morphology, necessitating a combination of quantitative techniques to assess the effectiveness of transesterification. These complexities are further exacerbated by the unique dynamics of pairing polymers with drastically different viscosities and residual additives, which causes inconsistent outcomes and contradictory findings in the literature. While blending compatibilization through transesterification, particularly PC-aromatic polyester blends, has been extensively studied, other impactful applications, such as synthesising high-performance ionomers or biodegradable copolymers, are largely underexplored. In addition, a significant research gap remains in exploring diverse polymer systems for innovating new materials and upscaling transesterification through advanced processing techniques such as reactive extrusion for practical relevance. Addressing these areas can fully utilise transesterification's versatility, especially in upcycling polyester waste into novel copolymer materials with tailored functionalities, fostering a circular economy. Such advancement in this field can progress new material development and offer a simple and cost-effective approach to bridging the gap between scientific innovation and industrial applications.