Tuning Colloidal Stability of Layered Double Hydroxides: From Monovalent Ions to Polyelectrolytes.

The growing number of applications of layered double hydroxide (LDH) colloids demands for detailed understanding of particle aggregation processes in such samples. Tuning the colloidal stability in aqueous suspensions is essential to design stable systems or to induce controlled aggregation of these elongated particles. In this review, recent progress in this field is summarized; in particular, the charging and aggregation of LDHs of various compositions and sizes in the presence of different aggregating agents are discussed. The review focuses on the effect of monovalent salts, multivalent ions, and polyelectrolytes on the suspension stability of LDHs. The provided information will help to better understand the origin of interparticle forces responsible for the colloidal stability and to design highly stable or aggregating LDH colloids according to the desired goals in certain applications. Moreover, potential future research directions to obtain a broader picture of LDH aggregation are also suggested.