A new approach to reconfigurable colloid assembly paves methods for adaptive smart materials

Self-assembly of colloids is the process in which colloidal particles spontaneously organize into ordered structures under certain conditions. Self-assembly of colloids serves as the basis for designing materials such as optoelectronic devices and sensors. One of the most interesting frontiers of colloidal self-organization is the development of active colloid assembly that exhibits dynamic behavior and can adapt to external stimuli.

Active colloids – colloidal particles that convert external energy into autonomous motion – are typical assembly units for active colloid assembly. While these active particles can demonstrate attractive self-organizing behaviors, controlling these behaviors in accuracy and real-time is a major challenge. The ability to dynamically adjust and manipulate colloid assembly is key to creating adaptive and reconfigurable functional materials.

The research project, led by Professor Wei Wang of the Harbin Institute of Technology (Deep Shenzhen), and Dr. Xi Chen of Chengdu Institute of Technology, introduced a new strategy to build active colloid assemblies. Published on Research, the work offers fresh insight into the design of smart materials with real-time on-demand reconstruction.

In their recent research, the research group took a step forward by combining chemical reactions and electropolarization to achieve in-situ adjustment of the reversible assembly and assembled structure. The assembled unit contains active particles and passive colloidal particles, where the active particles react with the chemicals in the solution to produce a chemical gradient. This gradient induces fluorescence and penetration that attracts surrounding passive particles and forms clusters of colloids.

Additionally, alternating electric fields are used to polarize passive particles, creating dipole dipole repulsion that helps incorporating the particles into a particular configuration. By fine-tuning the chemical and electric fields, the group accurately controlled the attraction and repulsion between particles, allowing for in-situ adjustment of the structure of the colloid assembly.

The team envisions applying these strategies to design a wide range of colloidal materials that can dynamically modify structure and functionality. This illustrates the steps to developing adaptive materials using a wide range of applications, ranging from responsive sensors to self-healing systems and reconfigurable devices.