A water-soluble interjacent complex that includes a first water-soluble polymer and one or more water-soluble monomers polymerized to form a second water-soluble polymer in the presence of the first water-soluble polymer. The water-soluble interjacent complex forms a solution in water that is free of insoluble polymer particles. The interjacent complexes may be used to treat a waste sludge by adding an effective amount thereof to the waste sludge. The interjacent complexes may also be used in making paper by adding an effective amount thereof to a pulp or a forming sheet at a suitable location on a paper making machine. The interjacent complexes may further be used as a rheology modifier in aqueous systems by adding an effective amount thereof to an aqueous medium to effect a desired viscosity, rheology, or flow curve property.