Design of new biopolymers for biomedicine and food-packaging

The limited fossil fuels reserves, as well as serious pollution problems, have led to a continuously growing interest in the use of sustainable materials obtained from renewable sources for many different applications. Among these materials, biopolymers, and in particular the class of biopolyesters, could potentially replace traditional plastics. Their versatility and their ability to undergo degradation in the environment where they are disposed, is of particular interest both for food packaging (when recycling is not possible due to organic matter contamination as well as multi-layered structures) and for biomedicine, in case of temporary applications, such as controlled drug release or tissue engineering. If these materials hydrolyse in the human body, it is possible to avoid the removal of the implant through surgery. In this framework, aim of the present research project was the synthesis and characterization of new bio-based and biodegradable polyesters and copolyesters, with tailored properties in relation to the intended use, in the fields of food packaging, which is one of the most demanding in terms of plastic sources, and regenerative medicine, as it represents the new frontier of biomedicine. The synthetic routes adopted (i.e. two-step melt polycondensation, ring opening polymerization and chain extension) are solvent-free, simple and economic, and can be easily used for industrial scale-up. Monomers from renewable sources were preferred over the ones obtained from fossil fuels. Moreover, copolymerization turned out to be a winning strategy to modify the polymers of interest. Starting from polyesters, the aliphatic (i.e. polylactic acid, poly(butylene succinate), polymers containing cyclohexane ring) and aromatic ones (i.e. polymers containing furan and thiophene rings), all characterized by high stiffness and low degradation rates, it was possible to obtain more flexible materials with higher biodegradation rates, particularly suitable for soft tissue engineering and for the realization of flexible food packaging films.