An emulsifier for use in forming a film for a suspended particle device (SPD) wherein the film is comprised of a cross-linked matrix polymer having a plurality of droplets of a liquid light valve suspension distributed therein. The emulsifier is formed of a copolymer material comprising at least first and second segments, the segments differing from one another in at least one of their chemical affinities, their compositions and their polarities. A first one of the segments is soluble in an uncured liquid matrix polymer used in forming the film, but insoluble in a liquid suspension medium of which the droplets are dispersed. A second segment is soluble in the liquid suspending medium in the droplets and insoluble in the uncured liquid matrix polymer. The first and second segments have substantially the same index of refraction and the index of refraction of the segments is within 0.010 of that of each phase of an emulsion formed with the emulsifier.