This talk will present some recent work on the assembly and optical characterisation of structurally coloured films comprising cellulose nanocrystals and other materials. The two basic fabrication approaches used are layer-by-layer deposition (LbL) of anionically charged cellulose nanocrystals (CNCs), produced by sulphuric acid hydrolysis, and cationically charged clay and the controlled drying of water/CNC droplets. To form structurally coloured films using LbL, systems comprising several sets of two different layers, of low and high refractive index, are formed. For the low refractive index layers a combination of colloidal silica and CNCs were combined. To form a high refractive index layer, polyethyleneimie (PEI) was combined with Vermiculite (VMT). Sequential dipping in each of these solutions led to the formation of multilayered films, also known as Bragg stacks. Alternatively we also investigated the drying of concentrated droplets of CNCs in water on a range of different substrates. A range of colored appearances is reported across each dried droplet, with different structural colors observed in different regions. This is thought to be due to the presence of both multilayers and chiral nematically arranged CNCs. In both cases (LbL and droplets) these CNC structures have been characterised optically. Multilayer modelling is also used to try understand the structures in more detail.

Structurally colored films using nanocellulose fiber

249th National Meeting (2015)

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