Hydrolysis properties of polyglycolide fiber mats mixed with a hyperbranched polymer as a degradation promoter

In response to the problem of microplastics, polyesters are attracting great attention due to their degradability in underwater environments. We recently demonstrated that the hydrolysis of linear polyglycolide (PGA) in a fiber state strongly depends on segmental dynamics in aqueous phases. This finding implies that the degradation of PGA can be controlled by tuning the segmental dynamics in water. Our choice of fiber geometry was based on its relatively large surface area-to-volume ratio. Herein, we examined the effects of the addition of a hyperbranched polymer (HBP) with a polyester skeleton and with many terminal hydroxy groups on the degradability characteristics of fiber mats. Dynamic mechanical analysis revealed that HBP acted as a plasticizer, especially in underwater environments. The weight loss of the PGA fiber mats was accelerated with increasing HBP content. In addition, structural analyses confirmed that crystal degradation had occurred and that hydrolysis-cleaved chains had crystallized. Considering that the structural changes in the PGA crystals depended on the feed amount of HBP, we claimed that HBP promoted PGA degradation in both the amorphous and crystalline phases. We believe that our simple strategy for accelerating the degradation of polyesters can provide suggestions for solving issues with microplastics. The effects of the addition of a hyperbranched polymer (HBP) on the degradability characteristics of linear polyglycolide (PGA) fiber mats. It was revealed that HBP acted as a plasticizer, especially in underwater environments. The weight loss of the PGA fiber mats was accelerated with increasing HBP content. Considering that the structural changes in the PGA crystals depended on the feed amount of HBP, it was claimed that HBP promoted PGA degradation in both the amorphous and crystalline phases.