Preparation of Degradable Polymers Containing Tunable Ratios of Dithioacetals and Disulfides via Mixed Mode Polymerization

Degradable polymers hold promise for their recyclability and their potential to facilitate the transition toward a circular economy of plastics. As such, a consecutive di-SN2 reaction between dithiols and polyhalogenated compounds was used to produce degradable polymers with tunable amounts of redox-enabled dithioacetal and disulfide linkages. The reaction employed bases of varying strengths and different thiol types, allowing for control over molecular weights ranging from <1 kDa to 16 kDa, with tunable degrees of polymerization ranging from 3 to over 75. The ratio of dithioacetals to disulfides was adjusted by manipulating the concentration of the methylene source, enabling the formation of polymers with up to 100% disulfide linkages or up to 93% dithioacetal linkages. This tunability resulted in polymers with multiple redox degradation pathways, capable of being degraded by either reduction or oxidation. Vinyl ether functionalized, telechelic oligomers were used as crosslinkers in network formation, yielding materials with multiple degradation pathways. This di-SN2 approach provides a promising and straightforward method for creating materials with tailored degradation characteristics.