Polymers containing β-thioether ester moieties in the backbone are important biodegradable materials that have been found applications in bio-related fields. This kind of polymer exhibits unique property change (increased hydrophilicity and degradation) upon oxidation of the β-thioether groups. Though several methods have been developed to synthesize such polymers, the control over the molecular weight, distribution, as well as end groups could not be achieved, which greatly limited the preparation of well-defined block copolymers and the structure-property relationship studies. We developed a simple approach to synthesize a β-thioether containing lactone monomer, 1,5-oxathian-2-one (OTO). The process is a one-pot two step procedure, Michael addition reaction between 2-thioethanol and p-nitrophenyl acrylate followed by intramolecular cyclization. The ring-opening polymerization (ROP) of OTO catalyzed by an organocatalyst DPP was investigated, and the results confirmed that living polymerization could be achieved under optimized conditions. Moreover, block copolymers of POTO and PEG or PCL were prepared in a controlled way. The amphiphilic block copolymer PEG-<i>b</i>-POTO could self-assemble into micellar like assemblies in water. We systematically studied the oxidation of the molecular assemblies with hydrogen peroxide. Based on the results of the oxidation of model small molecules, we proposed the pathway of the oxidation of POTO: the thioether groups were first oxidized into sulfoxides; before the sulfoxides were further oxidized into sulfones, the ester linkages began to break, causing the detachment of the PEG chains from the assembly surfaces. Finally, with more thioether groups have been oxidized and more ester groups have been broken, the assemblies began to change its morphology and disassembled into small molecules. This work clearly revealed that the oxidation of thioether group can increase the degradation of POTO in the interface of the micellar assemblies, thereby providing a guideline for using oxidation-responsive polyesters in drug delivery application.<br/>

Synthesis and oxidation-promoted degradation of β-thioether containing polyester

256th National Meeting (2018)

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