Entropy-Driven Ultratough Blends from Brittle Polymers

Polymer blends with synergetic performance play an integral part in modern society. The discovery of compatible polymer systems often relies on strong chemical interactions. By contrast, the role of entropy in polymers is often neglected. In this work, we show that entropy effect could control the phase structure and mechanical behaviors of polymer blends. For weakly interacting polymer pairs, the seemingly small mixing entropy favors the formation of nanoscale cocontinuous structures. The abundant nanointerfaces could initiate large plastic deformations by crazing or shear, thus, transforming brittle polymers (elongation < 9%) into superductile materials (elongation similar to 146%). The resultant polymer blends display high transparency, strength (similar to 70 MPa), and toughness (similar to 60 MJ/m(3)) beyond most engineering plastics. The principle of entropy-driven blends may also be applied in other polymer systems, offering a strategy to develop mechanically robust bulk polymeric materials for emerging applications such as biomedicine and electronics.

Automated summary

This study demonstrates that the entropy effect can control the phase structure and mechanical behaviors of polymer blends. For weakly interacting polymer pairs, the mixing entropy favors the formation of nanoscale cocontinuous structures, leading to superductile materials.