Effect of parameters of a crosslinked polyacrylic matrix on the impregnation of photoactive compounds in supercritical fluids

The effect of the network density of spatially crosslinked polyacrylic transparent matrices and the conditions of their impregnation with a photochromic compound via the use of supercritical carbon dioxide on the concentration of the introduced photochromic compound of the spiroxazin family is studied. The concentration of impregnated filler in a matrix is shown to increase with increases in the interjunction distance (below a certain level) and network chain flexibility as well as with increases in the temperature and pressure of the impregnation process. Impregnation in rigid networks occurs only in surface layers, whereas, in an elastic network, impregnation occurs in the entire volume of a sample. Matrices based on oligourethanemethacrylates are characterized by a good thermodynamic affinity toward spiroxazin photochromic compounds, a fact that makes it possible to increase the concentration of photochromic compounds in the matrix up to 3 wt % under conditions of supercritical impregnation. The photochromic characteristics of an impregnated compound are shown to be preserved in samples.