A research team led by Associate Professor Daisuke Aoki of Chiba University Poly has synthesised isosorbide carbonates (PICs) from non-toxic and biodegradable isosorbide (ISB), which is derived from glucose. PICs can be degraded by ammonolysis to give a mixture of isosorbide and urea, which can be directly used as a fertilizer. In this study, a modification method that endows PICs with further functions and/or tunable properties is introduced in order to establish a guiding principle for the design of materials based on PICs. 1,3:4,6-di-O-benzylidene-D-mannitol (DBM), which contains two hydroxy groups and two acetal structures, and is synthesized from D-mannitol, was successfully copolymerized with ISB to afford fully bio-based polycarbonates with a thermal stability that is comparable to that of conventional petroleum-based polycarbonates. The characteristics of the resulting polymers were easily modified by deprotection of the acetal group on the DBM units and subsequent post-modification with boronic acid to form boronate esters. Finally, the bio-based polycarbonates were successfully converted to fertilizer via ammonolysis, demonstrating a guiding principle for the design of materials based on a novel concept in which what has historically been considered waste plastic is used as a source of fertilizer.