Dynamic 3D Printing of Bottlebrush Block Copolymer Photonics

Biological systems have evolved to exhibit dynamic, hierarchical structures that confer complex functionality, such as the adaptable, structural color in chameleons that allows them to match their environment. Attaining such dynamic complex structures at the nanoscale have been challenging to achieve in synthetic macromolecular systems. In addition, synthetic colors we use today constitutes one of the biggest environmental pollutants that severely impact human and aquatic life. Developing printable dynamic structure color will not only introduce new functionality that current synthetic color is not capable of, but also help address this urgent environmental issue. Towards this aim, we and collaborators developed a programmable 3D printing process that can modulate nanoscale assembly and structure color of bottle brush block copolymers on the fly. By understanding and controlling the polymer assembly pathways during processing, we demonstrated 3D printing structure color as chameleon patterns without changing the ink material. We and collaborators further unveiled the underlying mechanism by probing polymer assembly pathways via a combination of X-ray scattering, optical spectroscopy, electron microscopy and coarse-grained simulations – the programmable structure color was attained through arresting polymer chain extension and entrapping metastable structures by controlling the assembly kinetics during printing.