From Thioether to Sulfone: Transforming Polyester Properties for Enhanced Degradation

Abstract

The escalating issue of plastic pollution, primarily due to plastic waste mismanagement and microplastic leakage, highlights the need for biodegradable polymers. However, the slow degradation rates of these materials in the environment necessitate innovative solutions for accelerating their breakdown. In this study, poly­(benzenedimethylene succinate)-co-poly­(benzenedimethylene thioglycolate) (PBDMS-co-PBDMTG) polyesters were synthesized with varying amounts of sulfur in a low oxidation state (thioether form), at molar ratios of PBDMS-co-PBDMTG: 76:24, 56:44, and 25:75, as confirmed by nuclear magnetic resonance spectroscopy (NMR). The thioethers were converted into hydrophilic poly­(sulfone-esters) (with the contact angle reducing from 80° for poly­(thioether-ester) to 43° for poly­(sulfone-ester)). This transformation, coupled with a decrease in crystallinity and the introduction of electron-withdrawing sulfone groups, led to ultrafast degradation kinetics both under basic conditions and in compost. The degradation rates were significantly different; poly­(thioether-esters) showed a mass loss of 9–19 mg/day, while poly­(sulfone-esters) exhibited a dramatic increase in mass loss, ranging from 2318 to 430 mg/day, depending on the sulfur content. This study demonstrates the potential for the use of poly­(sulfone-esters) as fast-degrading polymers for different applications.