Organo-clay hybrids based on dendritic molecules: preparation and characterization

摘要

Three generations of dendrons (G1, G2 and G3) with phenyl end-groups were intercalated into montmorillonite (MMT) layered silicates in dimethylformamide/water cosolvent. These dendrons synthesized via the convergent route were different in size and shape with molecular weights ranging from 930 to 5975 g mol~(-1). X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) indicate that the respective intercalations of MMT with Gl, G2 and G3 dendrons exhibited organized characteristics, and the interlayer spacings were 38, 77 and 115 A for G1/MMT, G2/MMT and G3/MMT, respectively. Furthermore, the modified dendron/MMT hybrids could be well dispersed into organic solvents, such as DMF, due to the presence of hydrophobic dendritic molecules. Our results indicate that organic/inorganic hybrids resulting from the association of dendrons and inorganic layered silicate can be obtained not only by ionic exchange reaction, but possibly by a direct organized route as well. Moreover, the preparation of dendron/MMT hybrids was investigated at different dendron/MMT molar ratios regarding the changes of interlayer distance. When the molar ratio is within the range of 0.25-1.0 cationic exchange capacity (CEC) equivalents, the d spacings increase from 19 to 38 A for G1/MMT, 15 to 77 A for G2/MMT and 14 to 115 A for G3/MMT, revealing a conformation change of the intercalating dendrons.