Recyclable and Robust Polyesters and Stereocomplexes

Based on Ring-Fused γ-Butyrolactones

Plastics which can be chemically recycled completely and infinitely

Background

Petroleum-derived plastics are major pollutants and diminish our natural resources, while biomass-derived, industrially-compostable plastics are unable to be effectively recycled. Typical recycling involves the melting of a plastic and re-purposing it to become a lower value product (downcycling), or mixed with a substantial amount of virgin material to maintain performance and processability. Researchers at Colorado State University have developed a new type of polymers that not only exhibit robust physical and mechanical properties to be practically useful but can also be completely recycled back to their building block monomers by thermolysis (heat) or chemolysis (catalyst), ready to be repolymerized and recycled repeatedly. Products made from recycled material then have equal integrity to those made from fresh raw materials.

Technology Overview

The invention consists of a new class of completely and chemically recyclable polyesters with practical, useful properties. Previously, polymers that can be selectively depolymerized back to monomers require low-temperature polymerization methods and also lack physical properties and mechanical strengths required of practical uses. Researchers at Colorado State University invented a polymer system based on a trans-ring-fused lactone monomer that can be readily polymerized under room-temperature and solvent-free conditions to ultra-high molecular weight linear polymers. The polymer has high thermostability and can be repeatedly and quantitatively recycled back to its monomer by thermolysis (by heat) or chemolysis (by catalyst). Physical blending of the two enantiomers of the polymer generates a highly crystalline stereocomplexed material with enhanced mechanical strength and high melting temperature. This new generation of chemically recyclable polymers offers a solution to the end-of-use issue of plastics and provides a closed-loop approach towards a circular materials economy.

Benefits

• Robust thermal stability
• Mechanical stregth
• Convenient Production
• Quantitative recyclability

Publication

Zhu, Jian-Bo, et al. “A Synthetic Polymer System with Repeatable Chemical Recyclability.” Science, American Association for the Advancement of Science, 27 Apr. 2018, science.sciencemag.org/content/360/6387/398.

Last updated: November 2019