Copolymeric mordant materials containing recurring units according to the following formula are disclosed: ##STR1## In such copolymers, each of R.sup.1, R.sup.2 and R.sup.3 can independently be alkyl; substituted alkyl; cycloalkyl; aryl; aralkyl; alkaryl; or at least two of R.sup.1, R.sup.2 and R.sup.3, together with the quaternary nitrogen atom to which they are bonded, can complete a saturated or unsaturated, substituted or unsubstituted nitrogen-containing heterocyclic ring; and X is an anion. The molar ratio of a:b can range from about 0.1:1 to about 10:1, e.g., about 0.3:1 to about 3:1. The copolymeric mordant materials can be utilized as image-receiving layers and in photographic products and processes of the diffusion transfer type. The mordants are especially adapted to the production of dye images free of objectionable haze, yellowing or related image defects.