TOUGHENING OF BIODEGRADABLE POLYMERS BY ENTROPIC MIXING: TOWARDS SUSTAINABLE PLASTICS

Abstract

This thesis proposes a principle for toughening of polymers through simple physical blending via favorable entropy effects. Following two simple criteria, we could rationally screen entropy-driven polymer pairs based on their interaction parameter χ and interaction strength k. In binary polymer blends, entropic driving forces leads to high miscibility, optimized interpenetrating network morphology. In ternary blends, entropic entanglements with a mutually miscible component enhances interfacial adhesion between immiscible polymers. For semicrystalline blends with moderate crystallinity (< 50 %), entropy has marked effects on crystal size and deformation modes, leading to mechanically robust bioplastics. This discovery shed new lights on the design of sustainable plastics for future sustainable electronics, agriculture and biomedicine. The proposed strategy is not limited to the studied blends but also proves applicable to other polymer systems.