Abstract
Large‐scale structural color flexible coatings have been hard to create, and patterning color on them is key to many applications, including large‐area strain sensors, wall‐size displays, security devices, and smart fabrics. To achieve controlled tuning, a micro‐imprinting technique is applied here to pattern both the surface morphology and the structural color of the polymer opal films (POFs). These POFs are made of 3D ordered arrays of hard spherical particles embedded inside soft shells. The soft outer shells cause the POFs to deform upon imprinting with a pre‐patterned stamp, driving a flow of the soft polymer and a rearrangement of the hard spheres within the films. As a result, a patterned surface morphology is generated within the POFs and the structural colors are selectively modified within different regions. These changes are dependent on the pressure, temperature, and duration of imprinting, as well as the feature sizes in the stamps. Moreover, the pattern geometry and structural colors can then be further tuned by stretching. Micropattern color generation upon imprinting depends on control of colloidal transport in a polymer matrix under shear flow and brings many potential properties including stretchability and tunability, as well as being of fundamental interest.
Qibin Zhao
Associate Professor
My research focuses on soft functional materials in which mesoscale structure controls optical and physical properties. I have worked extensively on colloidal and particle-assembled photonic materials, developing scalable processing methods to organize soft particulate systems into structurally coloured films and coatings. A central theme of my work is how external mechanical fields, such as shear, bending, stretching, and cyclic deformation, can drive microstructural ordering, lattice transitions, and structure-dependent optical responses. More broadly, I am interested in programmable soft photonic materials and functional coatings, where colloidal assembly, deformation processing, and soft-matter physics can be used to create adaptive optical, thermal, sensing, or mechanically encoded material functions.