Programmed photocontrol of polymer materials with multiple stimuli for fabrication and degradation.

Light-induced synthesis, degradation, and processing of polymer materials are powerful technologies in materials science that exploit the exceptional spatiotemporal resolution of light to achieve precise material control. Recently, the integration of precision synthetic chemistry with polymer materials science has led to the emergence of a new generation of photocontrol technologies. Such systems go beyond conventional, simple light-triggered approaches by employing multiple wavelengths of light, integrating light with multiple other stimuli that act independently, and implementing cooperative systems in which light and additional stimuli act in concert. Through such sophisticated designs, both bond formation and cleavage within polymer backbones can be precisely regulated, enabling unprecedented manipulation of polymer materials. These advances have unlocked diverse applications, ranging from functional materials for on-demand control of material degradation and adhesion to high-resolution microfabrication technologies, such as photolithography and photoprinting, as well as biotechnological fields, including drug delivery and control of cellular behavior. This Review highlights recent progress in polymer materials endowed with "programmed" photocontrol, focusing on emerging methodologies that enable polymers to be fabricated and degraded at desired locations and times. These advances offer an overarching perspective on the design and application of multi-stimuli photocontrol for creating next-generation polymer systems with advanced and programmable functionalities.