A facile route to synthesize hyperbranched polyester derived from cellulose and serine and its biodegradability

Cellulose-based hyperbranched polyesters (CHBP) have many prospective applications and are therefore a highly explored area. In this work, a novel biomass-based CHBP has been successfully prepared via the polycondensation of an ABn-type glycopeptide-like monomer (A and B are different functional groups, one A and two or more B in each repeated unit). This monomer was synthesized by reacting acetylated oligomeric cellulose halide with a Fmoc (Fluorenylmethyloxycarbonyl) group-protected serine via the Koenigs-Knorr reaction, followed by the removal of the protecting group. The branching degree of CHBP-3 is 0.55. Different characterization methods show that we have successfully synthesized hyperbranched polyester. The thermal properties were analyzed by thermogravimetric analysis (TGA) with results showing a superior thermal stability for CHBP compared to raw cotton fibers. CHBP also displayed better biodegradability than cotton fibers according to a colony degradation experiment. The study demonstrated a novel and practical route for the design and preparation of hyperbranched polyester using ‘green’ natural resources.