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Cellulose has a colourful future

14th December 2015


Cellulose nanocrystals, which are found in abundance in plants and trees, are attracting a high level of scientific interest for their potential uses in high-security and anti-fraud applications.

Widely acknowledged for their properties of strength and elasticity, cellulose nanocrystals in their liquid crystal form have a number of other intrinsic qualities that can help to create unusual optical effects, such as iridescence. The ability of cellulose nanocrystals to apparently change colour under different light conditions is due to the natural structure of the cellulose fibres, which naturally form a twisting pattern in their cholesteric phase. 

Drawing on this unique optical property, scientists are currently exploring the potential for cellulose nanocrystals to be used in technologies suitable for a wide range of applications – everything from bio-imaging, to flexible displays and anti-counterfeiting films.

A patent application filed recently in China describes how cellulose nanocrystals can be used to create a film that can act as a means of encryption, both for concealing sensitive information and for preventing visible information from being easily copied. When used in this way, the nanocrystals in the film cause it to appear to change colour when reflecting different kinds of light - a bit like a hologram device. By reacting differently to laser and polarised light, for example, it is possible for the film to create several layers of anti-fraud protection that are only visible under certain light conditions. The patent application explains how the technology could be applied to passports and other sensitive documentation as a sophisticated form of anti-fraud protection.

Such anti-counterfeiting and anti-fraud applications could have significant commercial appeal because holograms, which are currently widely used for similar purposes, can be costly to produce. While holograms typically require complex processing, naturally-occurring cellulose already benefits from an array of processing technologies, which means that any invention that makes use of the material is likely to be applied more widely and reach the marketplace more quickly. For example, a number of other patent applications in this area have described how a film made from cellulose nanocrystals could be used as a ‘unique marker’ for luxury goods such as handbags, some of which currently feature holograms, or for bank notes, which require a high level of anti-fraud protection.

In this fast-paced area of research, it is important that scientists consider the role of intellectual property protection at the earliest possible stage and professional advice is essential. When drafting an initial patent application it is important that the right amount of detail is incorporated in order to demonstrate that it is new and inventive. Of course, care should be taken to avoid early disclosure too, which could render the invention ineligible for patent protection and therefore commercially unviable.

As scientists continue to look to nature in the search for new and unique materials, they should keep in mind the challenges of the R&D pathway. Firms can only achieve commercial viability by implementing a robust IP strategy to protect their inventions.

Jennifer Unsworth, patent attorney and Alexandra Orrin, trainee patent attorney, are materials science specialists at intellectual property firm, Withers & Rogers





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