含磷钼酸的超分子复合材料的制备和结构研究

Synthesis and Characterization of Supramolecular Nanocomposites Based on Surfactant-encapsulated Polyoxometalate

介绍了一类端基含羧基结构的液晶性表面活性剂CDDA通过静电相互作用与磷钼酸(HPMo)进行复合,得到表面包覆柔性烷基链和羧基端基的复合物SEP-PMo,并通过元素分析、热失重等方法确认其化学结构.该复合物表现出稳定的液晶相,DSC,PLM,SAXS和TEM等研究表明其为层状相结构.进一步将SEP-PMo复合物与P4VP混合,通过羧基与吡啶环上氮的氢键相互作用,得到稳定的PMo和聚合物的复合物,同时对比研究了HPMo与P4VP直接共混后的静电复合物结构,表明经表面活性剂修饰后的PMo可在聚合物中保持其聚集态结构.

A surfactant-encapsulated polyoxometalate complex SEP-PMo was prepared by phosphomolybdic acid （H3PMonO40, abbreviated as HPMo）, via electrostatical interaction between HPMo and N-[ 12-（4- carboxylphenoxy） dodecyl]-N,N-dimethylammonium bromide （CDDA）. The resulting complex was characterized in detail by elemental analysis, thermogravimetric analysis （TGA） , as well as FT-IR spectra. SEP-PMo was further complexed with poly（4-vinyl pyridine） （P4VP） via hydrogen bonding interaction to get P4VP（SEP-PMo） n（n =0.01, 0.05, 0.1, 0.3, 0.5 and 1）. Mesomorphic phase behaviors of CDDA, SEP- PMo as well as P4VP（SEP-PMo） n were studied by a combination of differential scanning calorimetry （DSC）, polarized light microscopy （ PLM）, small-angle X-ray scattering （SAXS） and transmission electron microscopy （TEM）. Surfactant CDDA has a bilayer smectic A structure with a layer thickness about 4. 8 nm. When increasing the temperature to 140 ~C, the phase structure turns into a monolayer smectic A structure with a layer thickness around 2.4 nm. SEP-PMo exhibits thermotropic liquid crystal phase behavior induced by microphase separation from organic and inorganic composites. SAXS and TEM studies revealed that SEP-PMo could form lamellar structure with the layer thickness about 2.5 nm, and within the layer PMo has relatively ordered structure. Comparing with the phase structure of P4VP-PMo-n composites, the mesophase structure of SEP-PMo could be partially kept in the hydrogen bonded complex, P4VP（SEP-PMo）o.