The Adsorbed Layer of Gelatin on Silver Bromide—Its Nature and Photographic Significance

Publisher Website
Google Scholar
Abstract
Gelatin macromolecule adsorbed to silver halide crystals may strongly influence the formation, sensitization and processing of photographic emulsions. Experimental measurement of the properties of the adsorbed layer by ellipsometry (reflection polarimetry) have studied the effects of variations in the pH, pAg and ionic strength of the ambient solution, the external lattice face of Agllr, and of solution concentration, extraction, degree of phthalation and molecular weight distribution of the gelatin. The apparent irreversibility of the adsorption and the on set of “secondary” or multilayer ad orption have also been examined. Recent ellipsometric and hydrodynamic measurements indicate that over a wide range of experimental condition, gelatin molecules are adsorbed a monolayers of random oils, which are laterally compres ed but are otherwise only moderately deformed compared with thc solution state. Only a fraction of the clement are adsorbed to the ilver halide urface, so that to a large extent changes in the dimensions of the adsorbed layer parallel those of the gelatin molecules in solution. The implications of such a relatively extended, heavily solvated adsorbed layer on the preparation and subsequent treatment of photographic emulsion are described with special reference to experimental studie of the colloid stability and crystal growth of the silver halides. The functions that are only matched by binders which have a imilar balance of harged groups, and therefore an expanded configuration in the adsorbed layer, are unhindered cry tal growth, colloid protection, a high speed/fog ratio, flocculation and redispersibility, latent image tability and filamentary silver formation.

This publication has 0 references indexed in Scilit: