Ultra-strong, ultra-tough, and transparent polymer composite with excellent dynamic and biodegradable properties enabled by bicontinuous structure

Developing plastics that can integrate mechanical (strength and toughness) and dynamic properties (recyclability, repairability, and biodegradability) is commonly challenging. In this work, inspired by the reinforced concrete structure, an ultra-strong and ultra-tough sustainable polymer composite was constructed through uniformly dispersing cellulose nanofiber in a poly(vinyl alcohol) matrix to form a bicontinuous interwoven network structure based on strong yet dynamic hydrogen bonding crosslink sites. The obtained composite showed an ultra-high toughness, a high tensile fracture strength, good Young's modulus and transparency, as well as excellent dynamic properties including good healing ability, recyclability, and biodegradability. Besides, with excellent gas barrier ability and good water vapor permeability, the composite showed great promise to replace traditional polymers for food packaging and preservation. At last, the mechanism behind the good performances is expected to inspire the design of other healable and green polymers in the future.