Physical and Photographic Properties of Polyethylene Oxides

In the presence of gelatin no adsorption of the unsubstituted polyethylene oxides {PEO) on silver or silver bromide could be detected and it must be assumed that the concentration of PEO in the adsorbed gelatin layer is the same as in the bulk emulsion. It is supposed that the adsorbed gelatin layer is made more hydrophilic by PEO. This results in: (a) an accelerated fixation of a silver bromo-iodide emulsion in a concentrated sodium sulphite solution. Especially the solution of the iodide-rich parts of the grain surface is increased probably due to a stronger hydration of the silver ions. The iodide-rich phase is important in development on account of locally formed latent image. This explains, why developers in which solution physical development plays the prominent part, are strongly activated by PEO especially in the case of iodide-containing silver bromide emulsions ; (b) a decrease of the adsorption of hydrophilic developing agents. This applies to the di-anion of hydroquinone and explains the PEO-inhibition of alkaline hydroquinone development.