Preparation and characterization of hydrothermally pretreated bamboo powder with improved thermoplasticity by propargyl bromide modification in a heterogeneous system

A two-step strategy to improve the thermoplasticity of bamboo powder (BP) by the combination of hydrothermal pretreatment (BP-LHW) and propargyl modification (BP-PB/BP-LHW-PB) in a heterogeneous system was developed in this research. It was observed that the hydrothermal pretreatment has a positive impact on the alkyne-functionalized BP-LHW, resulting in substantial change including the etherification of BP-LHW with propargyl bromide, breaking of crystalline phase of the cellulose fraction. Besides, the modified sample is significantly changed in the apparent morphology and reduced in the thermal stability and glass transition temperature (Tg). The Tg is attributed to the increase of free volume due to the increase of propargyl concentration in the modified samples. These results revealed that the combination of propargyl group into pretreated BP is an efficacious way to ameliorate the thermoplasticity. Notably, the thermoplasticity of BP-LHW-PB with high concentration of propargyl is significantly enhanced compared to BP-PB, which is owed to the enhanced molecular mobility resulting from the reduced interaction forces between the cellulose molecular. Herein, the application way that the building a "clickable" alkyne platform in BP to obtain multifunctional materials will be broadened in bamboo-based materials. The bio-based material with improved thermoplasticity was prepared by grafting propargyl bromide onto bamboo powder.