Chemo-enzymatic preparation of copolymeric polythioesters containing branched-chain thioether groups

Area of Science:

• Polymer Chemistry
• Biocatalysis
• Organic Synthesis

Background:

• Polythioesters (PTE) are a class of polymers with diverse applications.
• Developing efficient and controlled synthesis methods for branched-chain PTE is of significant interest.
• Chemoenzymatic approaches offer environmentally friendly and selective routes for polymer formation.

Purpose of the Study:

• To synthesize branched-chain copolymeric polythioesters (PTE) via chemoenzymatic reactions.
• To characterize the structure and molecular properties of the synthesized PTE.
• To elucidate the formation pathways and identify low-molecular-weight byproducts.

Main Methods:

• Thiyl radical-induced addition of 1,6-hexanedithiol to dimethyl 1,18-octadec-9-enedioate.
• Enzymatic transthioesterification catalyzed by immobilized lipase from Rhizomucor miehei.
• Characterization using Gel Permeation Chromatography/Size Exclusion Chromatography (GPC/SEC) and Gas Chromatography-Mass Spectrometry (GC-MS).

Main Results:

• Branched-chain PTE were formed in approximately 87% yield.
• GPC/SEC analysis revealed an average molecular mass (Mw) of 1,857 Da, with a molecular weight range up to 24,000 Da.
• Chemical derivatization confirmed the formation of up to 58 mol% branched-chain thio(S)ether and identified various low-molecular-weight products.

Conclusions:

• Chemoenzymatic reactions provide an effective route for synthesizing branched-chain copolymeric polythioesters.
• The synthesized PTE possess controlled molecular weights and unique branched structures.
• Detailed structural elucidation of polymers and byproducts was achieved, offering insights into reaction mechanisms.