Micropatterned microplastic generation via degradation of polymeric films with micropatterned structures

Water-insoluble micropatterned films were prepared from poly(vinyl alcohol) (PVA) (or ethylene-vinyl alcohol copolymer (EVOH)) and poly(methacrylic acid) (poly(MAAc)). The carboxy groups in poly(MAAc) underwent dehydration reactions with the hydroxy groups in the vinyl alcohol units during heating at 135 °C, which resulted in crosslinking with ester bonds and formation of a polymeric network in the micropatterned films. The surface structures of the micropatterned films and the shapes of the peeled microplastics in the supernatant were measured after decomposition in an oxidizing environment, after ultrasonic irradiation, and with both. The results revealed that the micropatterns could be peeled off from the films after they were subjected to appropriate decomposition conditions and maintained their patterned shapes.