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

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

Plastic waste accumulation is an environmental emergency, as most plastics are not biodegradable; they mostly come from fossil sources, whose exploitation and depletion are also a reason for concern. Packaging is the market sector with the highest demand of plastics in EU. The recycling rate of 39.5% being far away from the target set by the European Commission, 55% by 2025, the packaging and consumer goods industries seek solutions for reducing its environmental impact. Packaging is now one of the largest application fields of bioplastics, i.e. plastics that are biobased and/or biodegradable. The challenge of a sustainable and recyclable gas barrier packaging material still needs to be addressed; currently, oil-based plastic foils or multilayer films that are single-use, neither recyclable nor biodegradable, are mostly used. ComBIOsites aims at developing recyclable composite materials for flexible packaging, using biobased raw materials and environmentally friendly processes, such as photopolymerization. Cellulose is the most abundant biopolymer on Earth. Nanocellulose (NC) is derived from cellulosic biomass through top-down approaches. NC films are good barriers against gases as oxygen and carbon dioxide, thus appealing for packaging applications. However, their hydrophilicity prevents their use in humid environments. It is therefore convenient to embed NC in crosslinked polymeric matrices, as in traditional composites, guaranteeing high mechanical performances and water/solvent resistance. To prepare the polymeric matrix a chemical process is required. Photocrosslinking is a green process, solvent-free, performed at room temperature and very fast, thus with low energy consumption, so attractive for industrial use. Crosslinking though can hinder recyclability. To tackle this issue, we combine NC with biobased prepolymers that we functionalize with a reversibly photocrosslinkable group, able to ensure the curing of the polymer upon irradiation at a given wavelength, and allow its dismantling at a different wavelength; the reversibility of the curing reaction opens up the possibility of recycling the composite at the end of its life cycle.

Data: CORDIS, © European Union