Chemical recycling of polymers back to monomer is one of the most attractive methods to retain value in polymer materials during the recycling process. Polymers with low to moderate ceiling temperatures (T<sub>c</sub>) are often employed in applications where recycling by depolymerization is desired. Polyacetals are a promising class of chemically recyclable polymers that exhibit a wide range of ceiling temperatures depending upon monomer structure. However, current catalyst systems for polyacetal synthesis are uncontrolled and produce polymers with low molecular weights and high dispersities, reducing the mechanical integrity of these materials and limiting their practical use. To access well-defined high molecular weight polyacetals, we have developed a highly selective catalyst system that facilitates the controlled polymerization of acetal-containing monomers. High molecular weight polyacetals of varying ceiling temperatures were synthesized that are thermally stable well above the polymer T<sub>c</sub> in the absence of catalyst. The influence of monomer structure on polyacetal mechanical properties, thermal stability, and polymerization thermodynamics were studied. We demonstrate that polyacetals with high thermal stability can be selectively depolymerized back to monomer at moderate temperatures using a separate depolymerization catalyst. The use of distinct polymerization and depolymerization catalysts allows for both synthesis and depolymerization of polyacetals under mild conditions, affording a practical method towards the catalytic conversion of polyacetals back to value-retained monomers.

Highly selective catalysts for the controlled synthesis and chemical recycling of polyacetals

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.