Phase segregation is ubiquitously observed in immiscible mixtures, such as oil and water, in which the mixing entropy is overcome by the segregation enthalpy^1,2,3. In monodispersed colloidal systems, however, the colloidal–colloidal interactions are usually non-specific and short-ranged, which leads to negligible segregation enthalpy⁴. The recently developed photoactive colloidal particles show long-range phoretic interactions, which can be readily tuned with incident light, suggesting an ideal model for studying phase behaviour and structure evolution kinetics^5,6. In this work, we design a simple spectral selective active colloidal system, in which TiO₂ colloidal species were coded with spectral distinctive dyes to form a photochromic colloidal swarm. In this system, the particle–particle interactions can be programmed by combining incident light with various wavelengths and intensities to enable controllable colloidal gelation and segregation. Furthermore, by mixing the cyan, magenta and yellow colloids, a dynamic photochromic colloidal swarm is formulated. On illumination of coloured light, the colloidal swarm adapts the appearance of incident light due to layered phase segregation, presenting a facile approach towards coloured electronic paper and self-powered optical camouflage.

在不混溶的混合物（例如油和水）中普遍观察到相分离，其中混合熵被分离焓^1,2,3克服。然而，在单分散胶体系统中，胶体-胶体相互作用通常是非特异性和短程的，这导致可以忽略不计的分离焓⁴ 。最近开发的光敏胶体颗粒表现出长程泳动相互作用，可以通过入射光轻松调节，这为研究相行为和结构演化动力学提供了理想的模型^5,6 。在这项工作中，我们设计了一个简单的光谱选择性活性胶体系统，其中TiO ₂胶体物种用光谱独特的染料编码以形成光致变色胶体群。在该系统中，可以通过组合不同波长和强度的入射光来编程颗粒与颗粒之间的相互作用，从而实现可控的胶体凝胶化和分离。此外，通过混合青色、品红色和黄色胶体，配制出动态光致变色胶体群。在彩色光照射下，胶体群由于分层相分离而适应入射光的外观，为彩色电子纸和自供电光学伪装提供了一种简便的方法。