March 2024 Newsletter-Disruptive Technologies and Structural Color

Ever worry about emerging technologies that might challenge your current business and make it obsolete? Do you regularly examine the moat around your business, make sure it is sound, and peer out past that moat to see what existential threats abound? Every business leader should be aware of developments that could potentially derail their business and/or provide opportunities for continued survival.

The consequences of not looking out for these threats can be disastrous. The “success trap” arises when an organization focuses efforts on what made it historically successful at the expense of exploration of new territories that will ensure long term viability. A well-known example of the phenomenon occurred with the advent of digital photography. The emergence of digital photography is also an example of a “disruptive innovation” as it created a new market at the expensive of an existing market.(1)

Eastman Kodak was incorporated in 1892, became one of the largest film and camera manufacturers in the world, and was a dominant player in that realm for most of the 20th century. The irony of their demise is that one of their employees actually developed the first handheld digital camera in 1975, long before the devices appeared on the market. Although Kodak was aware of the technology, they were late in shifting their business toward digital in the 1990s and early 2000s as capital investment would be high and such a move would impact their historical business based on photographic film. Kodak struggled financially in the late 1990s and attempted a turnaround by diversifying its chemical operations and shifting to digital photography and printing in the 2000s. Those efforts were not enough to prevent a bankruptcy filing in 2012.(2)

Technological advances in the expression of color may lead to a similar upheaval in the coatings industry which utilizes pigments (and dyes) for imparting color. The pigments can be natural or synthetic, and inorganic or organic. The inorganic pigments tend to be more stable and lightfast versus the organic pigments which exhibit colors that are brighter and richer than their inorganic counterparts. The pigments function by absorbing certain wavelengths of light and reflecting others; it is the reflected light that generates the color. The absorption of light in typical pigments leads to heat generation and temperature increases in those coatings where they are employed. (It should be pointed out that cool pigments do exist which act to reflect infrared light, rather than absorb it, thereby reducing heat gain.) The pigment industry also faces challenges due to increasing global regulations,(3) which have led to an increased reliance on production facilities in the Asia-Pacific region.(4)

Structural color is receiving more attention as an alternative to pigmented color. As opposed to the absorption and reflection of light in pigments, structural color is generated by the reflection and transmission of wavelengths of light by nano- and micro- structured materials. It is a phenomenon seen in nature, for example, in the colors of certain bird feathers and butterfly wings. In general, the colors generated structurally are more vibrant than those of their pigment counterparts, cover a broader color gamut, and can be resistant to fading over time.(5) A good example of the high brightness and high saturation of structural colors is the blue of the blue morpho butterfly above. (Note that Cypris Materials features a blue morpho in their literature.(6) More on Cypris later.)

There are many efforts afoot to develop structural color based coatings. One of the more recent developments is the work by researchers at Kobe University to develop color via the scattering of specific light wavelengths by spherical silicon crystals. The colors are generated by Mie resonance, where the wavelength of the light reflected is comparable to the size of the particles; the color is controlled by the size of the particles. The colors are non-fading, viewing angle independent, and can be generated in a monolayer, thus potentially leading to very thin and lightweight coatings.(7)

A team at the University of Illinois Urbana-Champaign is taking a different approach to structural color. They are generating color via block copolymers that can self assemble into nanostructures which reflect wavelengths of light that depend on the size of the assembling nanostructures. Crosslinking the polymers with UV light leads to changes in the color which provides a way to tune the color; the color depends on the crosslinking density which is a function of the amount of UV light exposure.(8)

Cypris Materials is pioneering the use of brush block copolymers to generate structural color. In their approach comb type polymers which have self assembling side chains are utilized. The light reflected is a function of the brush copolymer molecular weight; lower molecular weights reflect shorter wavelengths and higher molecular weights reflect longer wavelengths. Cypris is planning on launching a structural color copolymer this year (2024). They have also partnered with BASF to develop automotive coatings.(9) BASF is also working with Harvard to develop a model to describe how light interacts with nanoparticles embedded in a matrix to generate color.(10)

The examples of structural color described here are only a few of the more recent developments. So will structural color change the world of pigments and coatings as we know it? It is certainly starting to make a dent.

 

1.  https://en.wikipedia.org/wiki/Disruptive_innovation  Wikipedia Disruptive Innovation Wikipedia entry.

2.  https://en.wikipedia.org/wiki/Kodak  Wikipedia Kodak Wikipedia entry.

3.  https://www.inkworldmagazine.com/contents/view_online-exclusives/2019-03-07/regulatory-mandates-and-the-pigment-industry/  Regulatory Mandates and the Pigment Industry, Ink World Magazine, online exclusives, March 7, 2019. 

4.  https://www.custommarketinsights.com/report/pigment-market/  Global Pigment Market, Custom Market Insights, January 2024.

5.  https://www.nature.com/articles/s41377-022-00847-z  Andreas Tittl, Tunable Structural Colors on Display, Light: Science and Applications, 2022, 11, Article 155. 

6.  https://www.cyprismaterials.com/  Cypris Materials Website.

7.  https://phys.org/news/2024-01-ink-printable-iridescent-lightweight.html  Kobe University, Structural color ink: Printable, non-iridescent and lightweight, Phys Org, January 20, 2024. 

8.  https://cen.acs.org/materials/3-d-printing/Printable-polymer-tunable-structural-color/102/web/2024/02  Brianna Barbu, Printable polymer with tunable structural color, C&EN (online), February 26, 2024. 

9.  https://www.pcimag.com/articles/111657-self-assembling-structural-color-paints  John Book, Matthew Ryan, Toby Tang, Ryan Pearson, Kevin Turley, and Daniel Ferris, Self-Assembling Structural Color Paints, PCI Magazine, August 4, 2023. 

10. https://environment.harvard.edu/news/color-goes-beyond-nature  Leah Burrows, Color That Goes Beyond Nature, Harvard University Center for the Environment, March 3, 2021.