Molecular Design of Polymeric Compatibilizers for Improved Mechanical Recycling

Managing end-of-life plastics is a challenging problem for a variety of reasons, including the complexity of recycling mixed waste streams. Most polymer pairs don’t mix, and any product made from such a mixture will exhibit poor properties. These polymer mixtures can be enhanced by their compatibilization with proper polymeric interfacial modifiers. Our group has developed a fundamental understanding of polymeric compatibilizers for amorphous polymer blends. However, most polymers that end up in the waste stream are crystalline. In crystalline polymers, the compatibilizer may co-crystallize with either homopolymer providing a crucial mechanism to strengthen the biphasic interface. However, the importance of this mechanism, and understanding the compatibilizer molecular characteristics required to improve blend properties via co-crystallization, is poorly understood.  This presentation will provide the current state of our understanding of the role of co-crystallization in the compatibilization of crystalline polymer blends, and provide insight into the molecular characteristics of effective copolymeric compatibilizers for phase separated crystalline polymer blends, including those that are most relevant for mixed waste streams in polymer recycling.