Intercalation of sulfonated melamine formaldehyde polycondensates into a hydrocalumite LDH structure

• Sulfonated melamine formaldehyde (SMF) polycondensates were synthesized.
• Ca2Al–SMF-LDHs were obtained via rehydration of tricalcium aluminate.
• SMF polymers intercalate easily into a hydrocalumite type LDH structure.

A series of sulfonated melamine formaldehyde (SMF) polycondensates possessing different anionic charge amounts and molecular weights was synthesized and incorporated into a hydrocalumite type layered double hydroxide structure using the rehydration method. For this purpose, tricalcium aluminate was dispersed in water and hydrated in the presence of these polymers. Defined inorganic–organic hybrid materials were obtained as reaction products. All SMF polymers tested intercalated readily into the hydrocalumite structure, independent of their different molecular weights (chain lengths) and anionic charge amounts. X-ray diffraction revealed typical patterns for weakly ordered, highly polymer loaded LDH materials which was confirmed via elemental analysis and thermogravimetry. IR spectroscopy suggests that the SMF polymers are interleaved between the [Ca2Al(OH)6]+ main sheets via electrostatic interaction, and that no chemical bond between the host matrix and the guest anion is formed. The SMF polymers well ensconced within the LDH structure exhibit significantly slower thermal degradation.