Transition metal catalysed functionalisation of nanocellulose
D.Haridas,ij G. Garnier,jk J. Hooperjk
i Department of chemistry, Monash University, Clayton 3800, Victoria, Australia, jBioresource processing Reseach Institute of Australia(BioPRIA), kDepartment of Chemical and Biological Engineering,Monash University, Clayton, Victoria 3800, Australia
Nanocellulose, a promising material derived from the natural polymer cellulose, offers significant potential for developing sustainable and eco-friendly hybrid materials which has a wide range of applications, including in biomedical fields for drug delivery systems and tissue engineering, as well as in environmental technologies for water purification[1]. However, current methods for modifying nanocellulose often involve toxic chemicals, energy-intensive processes, and high levels of waste, which conflict with the principles of green chemistry[2]. Our research aims to address these challenges by exploring the use of transition metal catalysts as a greener alternative for nanocellulose functionalisation(Figure-1a). Transition metal catalysts are highly efficient and selective, allowing reactions to occur at lower temperatures with reduced energy consumption, less waste, and minimal use of harmful reagents. Our research focuses on developing two different strategies for grafting polymers and small molecules on to the surface of nanocellulose using innate functional groups . First approach involves an iron based catalyst for both radical decarboxylation and photo-ATRP polymerization, which enable the controlled polymer grafting on nanocellulose(Figure-1b). we achieved up to 99% monomer conversion, 70% degree of functionalization with respect to carboxylic acids, and grafting efficiencies up to 90%, with polymer dispersities in the range of 1.4–1.5. Furthermore, we successfully grafted ten different polymers from nanocellulose, demonstrating the broad applicability and robustness of this sustainable functionalisation strategy. Another method involves the use of borrowing hydrogen chemistry to graft small molecules on the surface of nanocellulose utilizing the innate hydroxyl groups. We were able to graft several amines with grafting efficiency upto 75% of available hydroxyl groups. Ultimately, this research aims to develop cleaner, more sustainable methodologies for nanocellulose modification, contributing to the creation of advanced materials that meet both industrial and environmental needs.
References
[1] Suryanegara, L., A.N. Nakagaito, and H. Yano, Cellulose, 2010. 17, 771-778.
[2] Thakur, V.; Guleria, A.; Kumar, S.; Sharma, S.; Singh, K Materials Advances 2021, 2 (6), 1872-1895.