CO2 permeability control in 3D printed light responsive structures

Azobenzene cromophores are proposed as functional dyes for the development of smart DLP-3D printable formulations. Two different azo molecules have been tested for the fabrication of membranes; taking advantage of the photoisomerization of these compounds, light induced changes in CO2 permeability have been studied showing a great increase of gas transmission upon green light irradiation. The investigations showed a linear increase of permeability with the increase of laser intensity, enabling a fine control of gas permeation. Moreover, these materials showed selectivity toward different gases, enabling a great increase of permeation upon laser irradiation for CO2 but not for O2. The use of the dye during the DLP printing process is necessary to confine the light inside the exposed layer allowing a precise printability without over-exposures; in this way complex architectures can be built and, at the same time, the choice of a molecule with intrinsic functionality transfers this functional property to the object. In the present study 3D structures presenting light triggered CO2 permeability have been built; as a proof of concept a smart 3D photocontrollable valve has been produced.