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Significance Statement
Natural opals are the national gemstone of Australia, which produces 97% of the world’s supply. “When we went to Australia to attend a conference in 2009, we notice there are natural opal jewelries sold in tax free shops of the Sydney Kingsford Smith International Airport. The price of those natural opals is very expensive, for example, high quality one even has equal price with diamond. However, we are more attracted by the beautiful and variable colors of natural opals, which are not produced from pigments but from the ordered deposition of spherical silica particles after years of siliceous sedimentation and compression under hydrostatic and gravitation forces” say Prof. Hailin Cong and Dr. Bing Yu, material scientists at Qingdao University, China.
Since then, they focused their research on how to make man-made opals and opal-like coatings with better color variation performance and much lower cost than the natural opals. After thousands of failed experiments, they finally invented a facile nanocomposition-polymerization method to prepare iridescent man-made opals and opal-like coatings with variable structural colors successfully. As shown in Figure 1, compared with natural opal (Fig. 1c and 1d) made from deposition of spherical silica particles in the long time formation of earth, the color variation of their man-made opal (Fig. 1a and 1b) is more obvious due to incorporating nano-scatterers into ordered deposition of spherical polymer particles. Additionally, the total cost to make such a man-made opal is less than 1 RMB, which is far more less than the natural opal (100 USD at least). Therefore, using the novel method created by Prof. Cong and Dr. Yu, we’re beginning to be able to play this game the way that previously only Mother Nature played it.
For detail, please refer: Hailin Cong,Bing Yu,et al.; Preparation of iridescent colloidal crystal coatings with variable structural colors; Optics Express, 2013, 21, 17831-17838.
Figure 1. Man-made polymer opals (a)(b) have better color variation performance and much lower cost than the natural opals (c)(d).
Opt Express. 2013;21(15):17831-8.
Cong H, Yu B, Wang S, Qi L, Wang J, Ma Y.
College of Chemical and Environmental Engineering, Qingdao University, Qingdao 266071, China. [email protected]
Abstract
Iridescent colloidal crystal coatings with variable structural colors were fabricated by incorporating carbon black nanoparticles (CB-NPs) into the voids of polystyrene (PS) colloidal crystals. The structural color of the colloid crystal coatings was not only greatly enhanced after the composition but also varied with observation angles. By changing the diameter of monodisperse PS colloids in the composites,colloidal crystal coatings with three primary colors for additive or subtractive combination were obtained. After incorporation of the PS/CB-NPs hybrid coatings into polydimethylsiloxane (PDMS) matrix, manmade opal jewelry with variable iridescent colors was made facilely.
