Fire-retardant, anti-dripping, biodegradable and biobased polyurethane elastomers enabled by hydrogen-bonding with cellulose nanocrystals
Yijiao Xue, Tianchen Zhang, Hong Peng, Zhewen Ma, Meng Zhang, Mark Lynch, Toan Dinh, Zhezhe Zhou, Yonghong Zhou, Pingan Song
Abstract
Thermoplastic polyurethane (PU) elastomers have attracted significant attention because of their many important industrial applications. However, the creation of fire-retardant and anti-dripping PU elastomers has remained a grant challenge due to the lack of crosslinking and weak interchain interactions. Herein, we report a mechanically robust, biodegradable, fire-retardant, and anti-dripping biobased PU elastomer with excellent biodegradability using an abietic acid-based compound as hard segments and polycaprolactone diol (PCL) as soft segments, followed by physically crosslinking with cellulose nanocrystals (CNC) through dynamic hydrogen-bonding. The resultant elastomer shows the balanced mechanical and fire-retardant properties, e.g., a tensile strength and break strain of 9.1 MPa and 560%, a self-extinguishing ability (V-0 rating in UL-94 testing), and an anti-dripping behavior. Moreover, the as-developed PU can be completely degraded in 1.0 wt.% lipase solution at 37 °C in 60 days, arising from the catalytic and wicking effect of CNC on PU chains. This work provides an innovative and versatile strategy for constructing robust, fire-retardant, anti-dripping, and biodegradable PU elastomers, which hold great promise for practical applications in electronic and automobile sectors.