Fully renewable photocrosslinkable polycarbonates from cellulose-derived monomers

Cellulose-derived photocrosslinkable polycarbonates (PCs) with renewable citronellol pendant chains were synthesised through the polycondensation of Triol-citro, a recently developed levoglucosenone-based triol monomer, and dimethoxycarbonyl isosorbide. The polymer structures were unveiled through NMR spectroscopy and four repeating units were identified: three hydroxy-functional linear units (Ln, Lo and Lp) and one dendritic unit (Dq). The relative percentages of the repeating units, as well as the molecular weights of the corresponding polymers, can be finely tuned by varying the catalyst and reaction conditions (i.e., polycondensation temperature and monomer concentration). Thermal analyses demonstrated that the novel PCs exhibited low glass transition temperatures (Tg as low as −72 °C) and Td5% up to 159 °C. These hydroxy-functionalised PCs are not only fully biobased with a controlled extent of branching, but they also bear citronellol side chains that were successfully crosslinked via ultraviolet irradiation to further control the polymer properties.