Description:
A new polymerization method that produces polyesters from bioderivable starting materials. The polyesters are unsaturated and may easily be further functionalized post-polymerization through cross-linking or other reactions with the unreacted vinyl group. Possible applications in biomedical, biodegradable polyesters, and thermally recyclable plastics industries.
At a Glance
- Catalytic ring-opening polymerization produces thermally recyclable polyester.
- Leaves the vinyl group on starting material untouched – available for further post-functionalization and/or cross-linking.
- Product is derived from biorenewable tulipalin A, is biocompatible and biodegradable.
- Polymer may be recycled via thermal treatment back to starting material in virtually 100% yield.
Detailed Description
Aliphatic polyesters, a class of biopolymers conveniently prepared by ring-opening polymerization (ROP) of certain cyclic esters or lactones, have received ever-growing interest for use in a wide range of applications, due to their biodegradability and biocompatibility. Alpha-methylene-gamma-butyrolactone (“MBL”, aka tulipalin A) is an attractive starting material for the synthesis of the corresponding biopolymer because it is biorenewable. However, in sharp contrast to other lactones, MBL and other gamma-butyrolactone based compounds are commonly regarded as "non-polymerizable" via ROP, meaning they cannot be used to produce polyesters.
This invention provides for the polymerization of MBL in a reaction that proceeds selectively via ROP to yield a polyester, incredibly leaving the highly reactive vinyl group of the starting material untouched and available for further functionalization, such as by heat or UV induced cross-linking or by further chemical reaction.
The invention has so far been demonstrated with an earth-abundant lanthanum complex but is part of a class of reactions developed recently by the inventors that have also been successful using so-called organic superbases (i.e., no metals). It is expected that the organic superbases will also catalyze this reaction with MBL, which would open the way for medical applications where polymers must be without trace levels of metals, such as biomedical applications.
Remarkably, the polyester product materials can be readily recycled back to the monomer in nearly 100% yield by simply heating the bulk materials at ~100 °C for 1 h in solution in the presence of a suitable catalyst, therefore demonstrating complete recyclability of the polymer. (The success of the thermal depolymerization with any post-functionalized variants will depend on the nature of the post-functionalization reaction.)
The products of this invention are expected to have potential commercial applications in the biomaterials, biomedical, biodegradable polyester, and thermally recyclable plastics industries.
