A facile strategy towards heterogeneous preparation of thermoplastic cellulose grafted polyurethane from amorphous regenerated cellulose paste.

Cellulose is an abundant feedstock with renewability and biodegradability. However, it is still challenging to manufacture natural cellulose products by environmentally friendly thermoplastic processing methods. Herein, we proposed a green approach for the heterogeneous preparation of thermoplastic cellulose grafted polyurethane (RCP-g-PU) from amorphous regenerated cellulose paste (RCP) via hydroxyl/isocyanate chemistry. First, amorphous RCP was fabricated through dissolving cellulose in sodium hydroxide aqueous solution and regenerating in polyethylene glycol, resulting in the enhancement of the accessibility of hydroxy groups in cellulose chains. Subsequently, a series of thermoplastic RCP-g-PU with the melt flow temperatures ranging from 160 °C to 226 °C were feasibly synthesized by adding hexamethylene diisocyanate into RCP without using other organic solvents. Eventually, the resultant RCP-g-PU can be directly hot-pressed into transparent films with flexibility and foldability. The reported methodology represents a sustainable route to achieve thermoplastic cellulose derivatives.