ComBIOsites: Reversibly photocrosslinked BIO-based composites with barrier properties from industrial by-products

In this poster the project ComBIOsites, funded by the European Union H2020 programme, will be presented. ComBIOsites aims at developing recyclable composite materials for packaging, using bio-based raw materials and environmentally friendly processes, such as photopolymerization. To this aim, we will use microfibrillated cellulose (MFC), and a bio-based prepolymer, functionalized with a reversibly photocrosslinkable group, able to ensure the curing of the polymeric matrix upon irradiation at a given wavelength, and to allow its dismantling upon irradiation at a different wavelength. Cellulose is an abundant, renewable and sustainable biopolymer, plus it is biodegradable. MFC films act as a good barrier against gases like O2, CO2 and N2, and are therefore appealing for packaging applications; however, their high hydrophilicity prevents their use in highly humid environments . It is therefore convenient to combine MFC with other polymers in the form of composites. Crosslinked matrices, as used in traditional composites guarantee high mechanical performances and water and solvent resistance, however, crosslinking often hinders recyclability. In the ComBIOsites project, MFC were obtained from hemp by-products; nanopaper and fully bio-based composites were produced with hemp MFC, and were characterized. The curing process was photocrosslinking, which is a green process, solvent-free and with low energy consumption, being performed at room temperature; plus being a fast polymerization process it is attractive for industrial use. Furthermore, recyclable crosslinked matrices were synthesized with bio-based prepolymers functionalized with groups undergoing reversible photocrosslinking, as demonstrated with petroleum-based polymers . This opens up the possibility of decrosslinking and thus recycling the composite material. Eventually MFC and prepolymers can be biodegraded or composted, and recent work suggests that the presence of natural fibers may accelerate the biodegradation of crosslinked biopolymers in soil .