Tough and strong soy protein film by integrating CNFs and MXene with photothermal conversion and UV-blocking performance

It is of great practical significance to prepare high-performance biopolymer composite films from renewable resources to replace ubiquitous petrochemical plastics. However, the unsatisfactory mechanical properties and single functionality of bio-polymers make them unable to meet the requirements of practical application. Herein, the tough, strong and renewable soy protein isolate (SPI) composite films with outstanding photothermal conversion and UV-blocking performance were prepared by facile blending and casting methods with integration of cellulose nanofibrils (CNF)@MXene hybrid nanosheets as reinforcers and branched polyethyleneimine (PEI) as a plasticizer. The resultant SPI/PEI/CNF@MXene films presented outstanding mechanical properties i.e., tensile strength of 17.31 MPa, toughness of 16.01 MJ/m3, high strain at failure of 114.10%. Furthermore, the SPI/PEI/CNF@MXene films can almost block 100% of UV spectrum and also exhibit satisfactory photothermal driven conversion. These comprehensive properties make it have great potential application as mulching films, packaging engineering, and UV-blocking fields.