Abstract
Development of colored surfaces by formation of nano-structured aggregates is a widely used strategy in nature to color lightweight structures (e.g. butterflies) without the use of dye pigments. The deposition of nanoscale particles mimics nature in it’s approach coloring surfaces. This work presents sol-gel modification of cellulose surfaces used to form a template for growth of Cu/Cu2O core-shell particles with defined size-distributions. Besides improving the adhesion of the deposited particulate material, the sol-gel matrix serves as a template for the control of particle sizes of the Cu/Cu2O structures, and as a consequence of particle size variation the surface color is tunable. As an example, red color was achieved with an average particle size of 35 nm, and shifts gradually to blue appearance when particles have grown to 80 nm on the sol-gel modified fabric. The copper concentration on representative fabrics is kept low to avoid modifying the textile characteristics and were all in the range of 150–170 mg per g of cellulose material. As a result of copper deposition on the surface of the material, the cellulose fabric also became electrically conductive. Remarkably, the electrical conductivity was found to be dependent on the average particle sizes of the deposits and thus related to the change in observed color. The generation of color by growth of nano-sized particles on sol-gel templates provides a highly promising approach to stain surfaces by physical effects without use of synthetic colorants, which opens a new strategy to improve environmental profile of coloration.
Highlights
Induced coloration is a phenomenon that is often associated with naturally occurring nanoscale structures, which lead to colorful appearances of some types of aquatic animals, birds and insects [1,2,3]
We report on a functionalization method for textiles by in situ growth of copper nanoparticles, which leads to coloration effects and imparts textiles with electrical conductivity that varies with the color of the fabric
The siloxane-based interlayer acts as an adhesion promotion layer and as a structured deposition template for the metal deposition
Summary
Induced coloration is a phenomenon that is often associated with naturally occurring nanoscale structures, which lead to colorful appearances of some types of aquatic animals, birds and insects [1,2,3]. While there are several ways to generate photonic or plasmonic structures on flat surfaces, creating these structures on textured substrates such as textiles is difficult and time consuming or adversely affects textile properties such as flexibility or elasticity In recent years, this topic has received increasing attention, resulting in multiple options to generate structure-induced colors on textiles. Systems made of self-assembled particulate structures have been investigated, consisting of either polystyrene-composite micro- or nanospheres, polymer-coated silicon nanoparticles, or metal nanoparticles [6,7,8,9,10,11] These coloration methods have in common that the nanoparticles are first prepared and stabilized before application by spin-coating or spray-coating with suitable binders. The color change occurs during the deposition process and results from structural changes on fiber and fabric surfaces induced by particle formation and growth
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