Intercalation of Sulfanilic Acid‐Phenol‐Formaldehyde Polycondensate into Hydrocalumite Type Layered Double ­Hydroxide

Polycondensates containing sulfonate groups, referred to as concrete superplasticizers, are widely used in the construction industry. A sulfanilic acid–phenol–formaldehyde polycondensate (SPF) with M_w ≈ 100.000 g · mol^–1 was synthesized from sulfanilic acid, phenol and formaldehyde by polycondensation reaction, and its intercalation into hydrocalumite type Layered Double Hydroxide (LDH) was investigated. Preparation was done by rehydration of tricalcium aluminate, a cement constituent, in the presence of the polymer. According to the XRD pattern, SPF was successfully intercalated. A d value of approx. 2.6 nm was found. Elemental composition of the new organo‐mineral phase reveals charge balancing of the cationic LDH main layers by the polycondensate. Thermogravimetry indicates that thermal degradation of intercalated SPF occurs at higher temperature, compared to non‐intercalated SPF. According to SEM imaging, the novel Ca‐Al‐LDH phase exhibits the morphology of intergrown platelets. Ultra‐thin nanosheets (foils) with approx. 50 nm thickness were obtained. The layered structure and d value obtained from diffraction analysis were confirmed by TEM imaging. The new hydride can be used as cement and concrete additive.