Dynamic synergistic effect induced by sepiolite, mica and halloysite as building blocks in strategic design of multifunctional ternary hybrids decorated with tertiary amines

A perspective on the integration of clays with different structures as versatile building blocks in design of alkylmethacrylate-based nanostructured hybrids was presented for terpolymer poly(diethylaminoethyl methacrylate-co-2-hydroxyethyl methacrylate-co-2-acrylamido-2-methyl-1-propane sulfonic acid) gels. The swelling of hybrids varied with the integration of three different components; Sepiolite, Halloysite, and Mica, with all clays acting as reinforcement in ternary structure, resulting in varying degrees of increase in compressive modulus. Highest improvement was observed in Sepiolite-doped hybrids, while addition of Mica provided limited increase. Addition of Sep increased the modulus of terpolymer hydrogel by 3.6-fold due to enhanced interactions at the nanofiller/terpolymer matrix interface, while addition of Hal and Mica resulted in improvements in mechanical properties of 2.8- and 1.6-fold, respectively. The presence of clay reduced swelling, decreasing the order from Blank > Halloysite > Sepiolite > Mica; the highest swelling occurred with addition of tubular Halloysite. Adding Sep to terpolymer matrix reduced the swelling by 2.0-fold, while Hal reduced it by 1.5-fold and Mica by 2.2-fold. Regarding the effects of cation-specific ions on hybrid strength, salt application caused significant changes in salt-induced elasticity during swelling in the presence of kosmotropic ions. An increase in salt concentration in solution led to “salting out” behavior in all clay types, while swelling was greater in presence of SO₄²⁻ anions compared to Cl⁻ anions. For anionic dye indigo carmine, the adsorption efficiency of hybrid cryogels synthesized at low polymerization temperatures was higher than that of hydrogels. Among the clays used, sepiolite-reinforced cryogels showed the highest efficiency at 92.6%, while Hal-reinforced gels had 91.1%, and mica-reinforced hybrids had the lowest capacity. The pseudo-second-order kinetic model represented adsorption kinetics and the process fitted Langmuir isotherm with equilibrium of adsorption of 121.29, 101.28, and 105.48 mg/g for sepiolite, hallysite and mica-doped hybrids, respectively. This study aims to be a pioneering research in the field of desing and development of ternary hybrids based on alkylmethacrylates, as ester of methacrylic acid, to investigate water absorption, mechanical, and adsorptive properties of structures filled with fillers of different morphologies.