Combining novel polyether-based ionomers and polyethylene glycol as effective toughening agents for polylactide

Abstract

Eco-friendly polylactide (PLA)-based materials with excellent toughness and transparency have wide application prospects in high value-added areas. However, toughening brittle PLA without losing its attractive transparency remains a great challenge for PLA-based blends because of the indispensable phase-separated structure. Herein, we synthesized a series of imidazolium-functionalized polyether-based ionomers by facile quaternization reaction from renewable epichlorohydrin elastomer and various comprehensive imidazoles. Combining these ionomers and polyethylene glycol (PEG) as toughening agents for PLA, we successfully achieved supertough, highly transparent and sustainable blends owing to a refractive index (RI) matching mechanism. The influence of the chemical structure of the ionomers, PEG molecular weight (Mw), and blending composition on the phase structure, mechanical performance, and transparency of the blends was systematically investigated. All the ternary blends exhibit remarkably high transparency (≥80%) and strain-to-failure (≥230%) owing to the similar RIs of each component and good compatibilization. Notably, the PLA/ECO-PF6/PEG20000 blend with 20 wt % PEG exhibits the highest strain at break (~400%) and impact strength of 82.2 kJ/m2. Pervasive matrix shear yielding induced by the internal and interfacial cavitation of the ionomer effectively dissipates the break energy because of the improved interfacial adhesion and plasticization of PEG20000. Combining RI matching and noncovalent bond interactions with a facile multicomponent compounding strategy provides us with an extremely cost-effective way to develop high-performance PLA-based materials for high value-added applications.