Dye microenvironment
An optimized photochromic dye microenvironment isolated from and dispersed within a distinct host phase.
1. A method for forming an optical article comprising:
selecting a photochromic dye;
optimizing an intensity of a color response of the photochromic dye within a dye matrix by selecting a composition of the dye matrix immediately surrounding the photochromic dye and controlling a characteristic of the photochromic dye through control of hydrogen bonding or dipole-dipole interaction with said composition of the dye matrix immediately surrounding the photochromic dye;
isolating the dye matrix containing the photochromic dye into solid dispersed phase particles;
forming two types of the dispersed phase particles, one with a low glass transition temperature microenvironment and the other with a high glass transition temperature microenvironment;
combining the two types of the dispersed phase particles; and dispersing the two types of dispersed phase particles within a host phase layer distinct from the dye matrix containing the photochromic dye, the dispersed phase particles with the low glass transition temperature microenvironment exhibiting a fast initial activation response followed by a gradual increase to a final desired optical density by the dispersed phase particles with the high glass transition temperature microenvironment, decreasing said final desired optical density rapidly to a lower level than said final desired optical density by the dispersed phase particles with the low glass transition temperature microenvironment and fading gradually back to a leuco form by the dispersed phase particles with the high glass transition temperature microenvironment;
wherein the photochromic dye and the dye matrix are permanently contained within the two types of the dispersed phase particles and separate from the host phase layer.
2. The method of claim 1 , wherein the step of optimizing a characteristic of the photochromic dye within the dye matrix comprises controlling a polarity of the dye matrix.
3. The method of claim 1 , wherein the step of optimizing a characteristic of a photochromic dye within the dye matrix comprises optimizing a neutral color tone of the photochromic dye.
4. The method of claim 1 , wherein the step of isolating the dye matrix containing the photochromic dye within the two types of the dispersed phase particles comprises forming a polymeric shell around the dye matrix containing the photochromic dye.
5. The method of claim 1 , wherein the step of dispersing the two types of the dispersed phase particles within the host phase layer distinct from the dye matrix containing the photochromic dye comprises dispersing the two types of the dispersed phase particles within a layer of a transparent material.