Ultrafast Infrared‐Induced Crosslinking of Polyvinyl Alcohol/Cellulose Nanocrystal Composites for Enhanced Water Resistance and Barrier Properties

Polyvinyl alcohol (PVA) has been extensively explored for its excellent film‐forming properties. However, its poor water resistance has limited practical applications. Crosslinking, a common method that enhances the water resistance, mechanical properties, and thermal stability of PVA films, is often employed. Although conventional hot‐air crosslinking can improve performance, it suffers from long processing times and high energy consumption. This study introduces infrared (IR) radiation instead of hot‐air heating to achieve ultra‐rapid crosslinking of PVA/cellulose nanocrystals (CNC) composites with poly (maleic anhydride) (PMA). Compared to hot‐air treatment, which requires 7200 s, IR treatment significantly enhances crosslinking efficiency, reducing the composite film's swelling rate by approximately 20% in just 120 s. FT‐IR analysis confirms that IR radiation promotes a more complete esterification crosslinking reaction. The IR‐treated composite film exhibited the best performance: water vapor transmission rate decreased from 1.447 g·m −2 ·d −1 (without heat treatment) to (0.175 g·m −2 ·d −1 ). The tensile strength of the composite film reached 47.18 MPa, significantly higher than the 39.03 MPa achieved with hot‐air treatment, and the strength retention rate remained as high as 92% at 50% relative humidity, along with superior thermal stability. This study provides a rapid, energy‐efficient new strategy for the efficient preparation of high‐performance PVA‐based composite films.