Recyclable and Robust Polyesters and Stereocomplexes Based on Ring-Fused γ-Butyrolactones

Plastics which can be chemically recycled completely and infinitely

At a Glance

  • The invention comprises completely recyclable biopolymers with linear and cyclic topologies via ring-opening polymerization of gamma-butyrolactone
  • Advantages include robust thermal stability and mechanical strength, quantitative recyclability, and convenient production method
  • Potential commercial applications include the packaging, microelectronics and biomedical fields


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.


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.


  • Robust thermal stability
  • Mechanical stregth
  • Convenient Production
  • Quantitative recyclability
Last Updated: October 2022

Collaborative or Funding Interest Welcome

IP Status

US Utility Patent Pending
PCT Patent Pending


Eugene Y Chen
Jian-Bo Zhu

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