Dec 3, 2024
4:15pm - 4:30pm
Hynes, Level 1, Room 103
Sara Fernanda Orsini1,Laura Cipolla1,Simona Petroni1,Sandra Dirè2,Riccardo Ceccato2,Emanuela Callone2,Roberta Bongiovanni3,Luisa Raimondo1,Silvia Mostoni1,Barbara Di Credico1,Roberto Scotti1,Roberto Nisticò1,Massimiliano D'Arienzo1
University of Milano-Bicocca1,Università di Trento2,Politecnico di Torino3
Sara Fernanda Orsini1,Laura Cipolla1,Simona Petroni1,Sandra Dirè2,Riccardo Ceccato2,Emanuela Callone2,Roberta Bongiovanni3,Luisa Raimondo1,Silvia Mostoni1,Barbara Di Credico1,Roberto Scotti1,Roberto Nisticò1,Massimiliano D'Arienzo1
University of Milano-Bicocca1,Università di Trento2,Politecnico di Torino3
Food waste represents a significance fraction of the whole waste production, and this study proposes an original synthetic strategy to valorize organic wastes in the development of a new packaging material, recyclable and able to ensure a longer shelf life to food. The idea is to manufacture transparent composites employing as raw materials starch and mineral fillers.<br/><br/>As widely reported, starch is an environmentally friendly alternative to the common petroleum-based plastics used in packaging and could be combined with silica and natural silicates to improve its mechanical properties. In fact, silicate-based nanoparticles (NPs) represent a powerful platform due to their high versatility connected to the possibility of easily modulating surface properties. This leads to specific and unique applications, such as the formulation of smart materials which have the ability to change their properties when exposed to external stimuli (pH, heat, light). Along this line, innovative key point of the project is the introduction of photoreversible cross-linking groups on both polymer and filler surfaces for the development of light-triggered biodegradable composites.<br/><br/>We here propose an innovative synthetic way to functionalize both yuca starch and silicate-based NPs with cinnamyl group (CINN) units, as natural and beneficial moieties capable of undergoing photoreversible dimerization through [2+2]-cycloaddition reaction. In detail, natural yuca starch was modified by a tailored etherification protocol that provides good flexibility to the two double bonds undergoing photodimerization. The functionalization of cinnamyl starch with three different degrees of substitution was assessed by NMR spectroscopy, revealing the generation of a covalent ether bond between the starch and the cinnamyl moieties. Furthermore, the photochemical properties of the systems were preliminarily verified by UV-Vis and NMR spectroscopy. Besides unveiling a competition between photodimerization and isomerization reactions, the results confirmed a partial but successful cross-linking reaction trough the [2+2]-cycloaddition of the double bond of the cinnamyl units.<br/><br/>Photo-responsive materials made of silica and sepiolite NPs bearing cinnamyl units, able to cross-linking with cinnamyl starch, were also developed. A new trialkoxysilane (CINN-APTES) covalently derived with cinnamic acid was firstly synthesized starting from 3-aminopropyltriethoxysilane (APTES). Upon structural assessment by NMR spectroscopy, the new molecule was exploited for functionalizing the surface of silica and sepiolite NPs. The covalent bond to the surface was confirmed by FTIR and solid-state NMR spectroscopy, whereas thermogravimetric and CHNS elemental analysis unveiled a functionalization degree much higher compared to that achieved by a conventional double-step post-grafting procedure. A proof of concept of the photoreversibility of the obtained fillers has been carried out.<br/><br/>Finally, filler and starch functionalized with cinnamyl groups were exploited for the preparation of light-triggered nanocomposites, whose photoreversible and mechanical features are currently under examination. Preliminary results envisage their potential application for smart packaging products.