Photochromic materials: pigments, inks, paints

Looking for a material that changes with the light?

OliKrom has acquired unique expertise in the field of photochromism and smart coatings: chameleon pigments, inks and paints that change color under the effect of light intensity (sunlight, optical source, laser,...).

We work in all industrial sectors: aeronautics, food, automotive, construction, cosmetics, defense, energy, luxury , medical, transportation...

Our custom photochromic products

Are you looking for a specific photochromic property adapted to your specifications?

Our teams master the most advanced scientific concepts in photochemistry, materials science, thermodynamics and phase transition to design your customized photochromic material: pigment, dye, ink, paint....

We select the most appropriate technology to meet your industrial specifications: organic photosensitive products (such as stilbenes, camphoras, o-nitrobenzyls, osazones, semicarbazones, etc.), hybrid or inorganic derivatives (such as metal oxides, alkaline earth compounds, metal halides).

We have a wide range of effects and colors with :

  • a positive photochromism: the photocommutable compounds generally present a stable colorless or pale yellow color state which is colored during irradiation.
  • a negative photochromism : photochromic compounds show a stable colored state A and a colorless form B, or reveal a reversible transition between different colors.

Our unique know-how in photophysics allows us to adjust the performance of the process: speed of photo-commutation, threshold of property change of inks and paints, positioning of the wavelength in the ultraviolet, visible and/or infrared.

One of the characteristics of photochromic materials is to bring into play during the mechanisms of excitation and relaxation, a stable State A which is transformed by irradiation towards a more or less metastable State B of different absorbance spectrum. Depending on the molecular structure, the B-form can be converted back to the A-form by thermal and/or photochemical means.

This knowledge of the mechanisms allows us to avoid the pitfalls frequently encountered with photochromic materials: instability and/or fatigability of the phenomenon, non-optimal optical properties... We control the photochromic technology according to the demand to become reversible or irreversible.

Reversible photochromism

photochromic-paint-reversible

Transformation of property at a defined light power, return to its original stable state when the light intensity returns to its initial level. Possibility to customize the colors, the excitation wavelength, the photo-commutation speed and the reversible or irreversible effect.

Irreversible photochromism

photochromic-paint-irrreversible

Definitive transformation of properties at a defined light intensity threshold (sunlight, laser,...). Possibility to adapt on demand the threshold, the excitation wavelength (ultraviolet, visible, infrared) or the light-induced speed.

Our expert scientific team in photochromism

By experience, we know the main pitfalls encountered with photochromic products (in powder pigment/dye form, ink, paint...): a speed of inscription and erasure that is too slow or too fast, a dependence of the kinetics on temperature, a degradation of properties during the formulation and/or the industrial process, sensitivity to ultraviolet light, etc.

This is why we have chosen to be with you from start to finish, from the idea to the final product (from the pigment to the ink/paint), in order to intervene efficiently at each stage of your project: research and development, pre-industrialization and industrialization.

Photochromism: fields of applications

olikrom-space-defense

Space & Defense

In aeronautics and defense, the use of photochromic derivatives makes it possible to create coatings with enhanced properties, interactive with their environment to counter laser aggression or induce camouflage, like a chameleon in nature.

In the space domain, photochromism and thermochromism are two mechanisms particularly studied to capture solar energy and/or to protect themselves from the sun's rays by changing color...

photochromic lenses

Health

In the field of ophthalmology, the uses of photochromic coatings are mineral or organic photochromic lenses, which darken in reaction to ultraviolet wavelength.

  • Mineral lenses usually incorporate a silver halide compound in their structure. Under UV exposure, the silver-halide bond dissociates in favor of an Ag-Ag interaction, which darkens the glass. This metastable organization fades away and the silver-halide bond reforms as soon as the UV exposure is stopped, restoring the clarity of the lens.
  • Organic lenses are usually coated with a layer of oxazines. Under the effect of UVs (of the sunlight), a structural change takes place and the lens darkens. As soon as the UVs are stopped, the initial thermodynamically stable state is restored and the clarity of the glass is regained.

Active glazing for responsive facades

Industry & Construction

  • In the building industry, photochromic coatings (paint, ink...) offer a multitude of opportunities for sun protection: dynamic glazing, photochromic agricultural greenhouses...
  • In the industrial field, the use of irreversible photochromism allows the watermarking of parts by laser treatment (authentication, anti-counterfeiting, personalization of an object...). The modulation of the optical properties (colors,  wavelength) is adjusted according to the laser (energy, wavelength,...).

For security, tunable photosensitive products are of interest as sensors, especially to inform of repeated or prolonged exposure to ultraviolet excitation.

What is a photochromic material? A photochromic (from the Greek photôs light and chromos color) coating, ink, paint is, by definition, made up of a pigment/colorant whose absorption spectra change according […]

Sensitive, reactive, these so-called smart coatings transform and switch color under the influence of heat, light or mechanical stimulation (stretching, impact). Behind this SmartKrom® property, these products involve a physical process of phase transition linked to a modification of the structure. This is not magic! […]