Exploring the Application of Sustainable Poly(propylene carbonate) Copolymer in Toughening Epoxy Thermosets

Abstract

Herein, poly­(propylene carbonate) (PPC) was used as initiator for ε-caprolactone polymerization to produce the poly­(ε-caprolactone)-<i>block</i>-poly­(propylene carbonate)-<i>block</i>-poly­(ε-caprolactone) (PCL-PPC-PCL) triblock copolymer, enabling innovative application of PPC as a toughening agent of epoxy thermosets. The interfacial interaction between PPC modifiers and epoxy was enhanced significantly because PCL blocks were miscible with epoxy matrix. The size of separated PPC modifiers decreased dramatically as the amphiphilic block copolymer formed nanophases in epoxy host. Consequently, with the incorporation of 30 wt % PCL-PPC-PCL modifier into the thermoset, the tensile elongation and the area under the stress–strain curves increased by more than 320% and 180%, respectively, compared with neat epoxy, indicating that an excellent toughening effect was achieved using this strategy. Considering that PPC possessed an ocean of attractive properties but suffered from its low glass transition temperature in implementation as mass products, this work may open up opportunities to extend the applications of PPC