A host material with the ability to encapsulate anionic substances was produced by intercalation of three cationic polyelectrolytes into synthetic sodium fluorotetrasilicate mica (Na-TSM). The polyelectrolytes, polyethylenimine (PEI) and poly(allylamine hydrochloride) (PAH) directed the conformation of the intercalated polycation and its ability to accommodate anionic guests, depending on its state of protonation. The quaternary ammonium polycation poly(diallyldimethylammonium chloride) (PDDA), which had the lowest charge d. of the three polymers studied, adopted a coiled conformation within the anionic host at both high and low pH, resulting in excess cationic sites within the interlayer of the polysilicate. Powder x-ray diffraction patterns and adsorption isotherms showed two different stages of PDDA intercalation with different adsorption free energy. At. force microscopy images showed that the PDDA-clay nanocomposites maintained the shape of the original nanosheets, indicating successful conversion of the lamellar host into a 2D material with anion exchange capacity. The anion-accepting ability of these nanocomposites was quantified by studying the encapsulation of a bulky anionic blue dye as a function of loading of PDDA. From dehydration and x-ray powder diffraction expts., the dye-polyelectrolyte-clay nanocomposites possessed two kinds of interlayer galleries, and the anionic dye was site-selectively intercalated into hydrated galleries in which PDDA strands were coiled. [on SciFinder(R)]