Transparent photochromic material with fast light and colour control

The Spanish SME, founded in 2014, is run by a team that accumulates on average more than 10 years of experience on photochromic materials and micro-/ nanoencapsulation. Photochromic dyes can change their colour when exposed to light. Their practical applications to ophthalmic, sport eyewear, and smart windows has driven researchers in the continuous design and synthesis of novel photochromic dyes with optimized performances in polymeric matrices. However, whereas the colour change of these dyes can be fast in liquid solutions, they are hindered and slowed down upon integration into a solid matrix such as lenses. This is perceived as an inconvenience by the users, and can compromise visibility for automotive applications such as motorcycle face shields, preventing a deeper market penetration. To avoid this, the company has developed an efficient, straightforward and universal strategy to embed commercial photochromic dyes in a polymeric material, without compromising their optimum solution absorption and isomerization kinetics. Their solution is based on trapping emulsified nanodroplets of a dye solution into a liquid‐filled nanocapsule or directly into polymeric matrix (Figure 1). This technology is capable of producing liquid-core nanostructured materials with liquid-like photochromic response. By selecting the nature of the liquid core, solid stable materials are prepared with solution‐like colour‐changing rates that are at least tenfold faster than those measured for rigid polymer thin films and particles (Figure 2). The optical material comprising this nanocapsules is prepared through a straight forward process using commercially available materials, without further modification of the components. The films manifest true liquid-like kinetics and finely tunable photochromic behaviour, with a high transparency. The films are also recyclable, show enhanced fatigue resistance and its preparation is scalable. These traits make them highly suitable for lenses, sport eyewear and smart glass applications (Figure 3). The SME is interested in establishing a license agreement with industrial partners willing to industrialize the production of end-products based in this patented technology to bring it onto the market. Alternatively, the SME is also open to technological cooperation agreements to develop customized photochromic solutions through this technology for eyewear, automotive and smart windows manufacturing companies.