Three dimensional nanoporous density graded materials formed by optical exposures through conformable phase masks

Control of spectral bandwidth, illumination angle, and degree of collimation of light passing through a conformable phase mask provides an experimentally simple route to nanostructured materials with well defined depth gradients in density (i.e., porosity). In this approach, the illumination conditions define spatial variations in visibility of the distributions of intensity. Exposure of photopolymers to these intensity distributions generates, after developing, solid structures with geometries that compare well with expectation based on modeling of the optics. A range of structures is demonstrated, some of which have potential applications ranging from targets for laser fusion to vehicles for controlled release of chemicals.