Abstract
N-isopropylacrylamide (NIPAAm) composites intercalated with Li-, Na-, K-, tetramethylammonium-, n-octyltrimethylammonium- and trimethylstearylammonium saponites, Na-montmorillonite and Na-hectorite were prepared by solid-liquid and solid-solid reactions. The intercalation was confirmed by powder X-ray diffraction and ignition loss. For solid-liquid reaction the interlayer spacing expanded to c.a. 0.4nm in the Na-saponite treated by 8.8-14mmol L^<-1> NIPAAm aqueous solutions and 0.7nm in that treated by 18mmol L^<-1> solution, indicating a monolayer structure of the NIPAAm constructed in the interlayer space at low intercalation level changes to a pseudo-bilayer structure at high intercalation level. It is presumed from the expansion of interlayer spacing that the amount of intercalated NIPAAm is larger in saponite than hectorite and montmorillonite when they are treated by the solution of the same concentration of NIPAAm. In saponites, the amount of NIPAAm adsorbed was decreased largely by the exchange from Na^+ to bulky organic cations such as, n-octyltrimethylammonium- and trimethylstearylammonium. On the other hand, the cation exchange among alkali metal ions affects scarcely to the amount of intercalation. The dominant interaction which governs NIPAAm intercalation is considered to be hydrogen bonding between N-H in NIPAAm molecule and oxygen at the surface of clay layer. In the case of tetramethylammonium- and n-octyltrimethylammonium-saponite, the nanocomposition with NIPAAm in solid-liquid reaction was dominated by adsorption into micro- and mesopores in the clay.
