COLOUR delivered results beyond the state of the art in bio-inspired photonic pigments by moving from proof-of-principle structural colours to a controllable, hybrid and application-oriented pigment platform. The project established robust emulsion-confined block copolymer self-assembly routes for photonic microparticles and demonstrated multiple technical advances that address key limitations of existing photonic pigments (insufficient brightness, scattering-induced “whiteness”, limited functional integration and weak routes to coatings).
Key results beyond the state of the art include:
(1) Morphology-by-design for tailored optical response. Beyond concentric lamellae, COLOUR developed control over additional architectures, including anisotropic particles with stacked lamellae, enabling angular-dependent optical behaviour as a new degree of freedom for photonic pigment design.
(2) Hybrid refractive-index engineering while preserving photonic order. The project demonstrated that high-index components can be incorporated in a domain-selective manner while maintaining lamellar ordering, strengthening brightness and extending the platform towards multifunctional hybrid photonic pigments (including routes to incorporate different classes of inorganic nanomaterials).
(3) Improved strategies to suppress incoherent scattering without sacrificing brightness. COLOUR refined absorption integration by moving from a single broadband absorber concept to a bandgap-tailored approach (using complementary dyes positioned outside the photonic bandgap), improving colour contrast whilst largely preserving photonic peak intensity.
(4) More controllable routes to complex architectures. Core–shell concepts were advanced using microfluidics, enabling controlled generation of core–shell photonic capsules and additional control through osmotic effects, providing a credible pathway to architectures that combine absorption and structural colour in a reproducible manner.
(5)Translation to macroscopic demonstrators. Optimised pigments were integrated into binder-based formulations and used to produce structurally coloured coatings/paint demonstrators, supporting the feasibility of application in surfaces and coatings.
These results have potential impacts across sustainability-driven markets where colourants are used at scale. Structurally coloured pigments can reduce reliance on hazardous or fading dye chemistries and enable durable, non-toxic colour solutions aligned with European sustainability priorities. Beyond colour, the demonstrated hybrid and responsive routes open opportunities in higher-value applications such as functional surfaces, sensing concepts and anti-counterfeiting approaches.
To ensure further uptake and success, several next steps are needed: (i) scale-up and process engineering, including pilot-scale production (e.g. intensified/parallelised microfluidics and continuous processing) and quality control of colour metrics; (ii) performance validation of coatings under relevant mechanical and environmental conditions (abrasion, weathering, chemical resistance) and formulation optimisation for industrial application methods (spraying, roll-to-roll, printing); (iii) standardised characterisation protocols for structural-colour pigments (colour stability, angular response, durability), supporting comparability and market acceptance; and (iv) exploitation support, including IP strategy where appropriate, engagement with industrial partners for demonstrator validation, and access to financing for pilot production and market entry. Overall, COLOUR provides a strong scientific and technological foundation for sustainable photonic pigments and their translation towards real-world coatings and functional materials.
