Shedding light on surfaces—using photons to transform and pattern material surfaces

The ultimate goal of surface modification is to quantitatively control surface properties by precise manipulation of surface chemical structure at the molecular level. Advances in the understanding of molecular design principles for soft matter surfaces can be combined with the available arsenal of interesting photochemical reactions to create an exciting paradigm for surface modification: the use of photons to both transform and pattern chemical functionality at soft matter surfaces. The success of the paradigm is predicated on the ability to design and synthesize “photochemical surface delivery vehicles”, complex photoactive molecules that form stable surface monolayers and subsequently deliver photoactive moieties to the surface. Shedding light onto these smart, modified surfaces brings about a wide variety of precise photochemical reactions that are preprogrammed within the surface delivery vehicle. Surface chemical patterns are formed by exposure through a mask. Some photochemical surface transformation can be considered as “green” chemistry since only photons are required as reagents. In this review, we provide a brief tutorial on photochemistry fundamentals to illustrate the nature of possible photochemical surface reactions and discuss the principles of design for photochemical surface delivery vehicles. Applications of the paradigm drawn from a variety of fields emphasize the tremendous potential for photochemical surface transformation and patterning on both hard and soft substrates.