Superstrong and Ultratough Hydroxyethyl Cellulose-Based Structural Materials Enabled by the Synergy of Microphase and Orientation.

Petroleum-based structural plastics are indispensable in industry and daily life but are environmentally problematic. Cellulose is an ideal ecofriendly polymer with abundant availability, renewability, and biodegradability, but it fails to serve as structural plastics due to the lack of combined high strength, toughness, and heat resistance. Herein, we report superstrong, ultratough, and heat-resistant cellulosic plastics through integrating abundant microphases (100-300 nm) and molecular orientation into cellulosic plastics, with the design principle that orientation can enhance the tensile strength and heat resistance based on the enhanced restriction on chain-segment motion while numerous small-sized microphases (100-300 nm) can force the motion of extensive oriented rigid chain-segments via serving as stress concentrators. The unique mechanism, integrating restricted chain-segment motion and forced chain-segment motion, is unprecedented, and enables the high strength (204.1 ± 10.8 MPa), high toughness (27.1 ± 1.6 MJ/m3) and high heat resistance (good shape retention after heating at 180 °C for 10 min) of cellulosic materials. Additionally, the resulting materials also possess good transparency and effective UV shielding. This work provides a new perspective for regulating chain-segment mobility and offers a promising pathway for developing sustainable alternatives to petroleum-based structural plastics.