Development of novel formulations based on biopolymers

Biopolymers, generally prepared from renewable sources, have attracted increasing attention due to their unique properties, such as nontoxicity, biodegradability and biocompatibility. Indeed, the above materials have been widely applied in the biomedical field, in the development of electronic devices as well as in the food packaging. Two of the most extensively studied and exploited biopolymers are poly(lactic acid) (PLA) and polycaprolactone (PCL), which have been the objects of the present work. Despite the significant interest in these polymers, for large-scale exploitation of both PLA and PCL, it is necessary to take into account some specific issues concerning their properties. In this regards, it is relevant to underline that the methods, which can be applied for improving their characteristics or those used for disclosing new features, have to take into account the economic impact and the "bio" nature of the material, which should be maintained in the final formulation. In particular, in the case of PLA, one of the major issues, which reduces its exploitation in durable applications, is its low hydrolytic stability, compared with other similar materials. Moreover, in the applications requiring high gas barrier, the use of PLA is critical and needs a further reduction of its gas permeability. Furthermore, concerning exploitations, where electrical and thermal conductivity is demanded, the insulating nature of the above biopolymers, requires the applications of proper conductive fillers. As such, the main aim of the thesis work main has been the improvement of the two biopolymer properties, developing novel formulations, whose design has taken into account all the mentioned issues. In the case of PLA, the barrier properties, the resistance to hydrolytic degradation as well as the antistatic features have been improved by modifying the material surface by means of the application of methods based on the chemical grafting or the Layer by Layer deposition and on the use of proper fillers, such as Polyhedral Oligomeric Silsesquioxane (POSS) and graphene oxide (GO). In addition, formulations capable of imparting thermal and electrical conduction to both PLA and PCL have been studied, combining the two biopolymers with graphite nanoplatelets (GNP).