Synthesis And Charcaterization Of New LDHs-Based Functional Materials

Intercalated supermolecular materials are inorganic-organic hybrid materials which are synthesized by intercalating some functional ions or organic molecules into inorganic sheets.As a class of anionic clay,the typical structure of layered double hydroxides(LDHs)is three-dimensional crystal made up of ordered vertical arrangement of two-dimensional nanosheets,and the interlayer anions can be exchanged.Therefore new functional LDHs-based materials can be prepared by ionic exchange method,rehydration using structural memory effect,layer-by-layer assembly method.Firstly,due to the tackiness of intermediate ferric hydroxide,new nano-branched Ni/Fe-LDHs were successfully prepared by coprecipitation method without adding a third adhesive.Effects of different factors like concentration,reaction time were investigated,and the optimal conditions were acquired as concentration is 0.165M,pH=10,reaction time is 48h by researching the morphology of product.Secondly MgAl-NO3-LDHs have been synthesized as precursors by one step method,and then aminotriacetic acids(NTA)were intercalated by anion exchange method under nitrogen atmosphere to synthesis MgAl-NTA-LDHs.When the ratio of-COOH:NaOH is 2:1,the pH of solution which is suitable for preparing AlOOH is about 7-8.MgAl-NTA-LDHs were successfully synthesized when the ratio of-COOH:NaOH is 3:1 and the pH of solution is about 11-12.The FT-IR spectra of MgAl-NTA-LDHs shows that the bands at about 1738cm-1(5.75 ?m)of the stretching vibration of C=O shifted to lower frequency(1606 and 1415cm-1,6.22 and 7.06?m),demonstrate that the COOH groups had been converted into COO-after intercalation and also indicates the excellent infrared absorption in the range of 7-8?m(1428-1250 cm-1).In addition,MgAl-S2O3-LDHs were successfully fabricated by using the memory effect of LDO.The FT-IR spectrum indicates that both the materials have excellent infrared absorption abilities in the range of 7-25 ?m.Finally,(MMT/BNMA@PVA/LDHs/BNMA@PVA)n multilayer thin films were fabricated by layer-by-layer(LBL)assembly.Exfoliated LDHs and MMT were chosen to fabricate inorganic building blocks,which are expected to provide an electronic field for the functional molecular(BNMA).UV-visible absorption spectra and Photoluminescence spectra demonstrate that the absorption and intensity linearly increase with the layer number n,which means the layer assembly is ordered and periodic.The average life time of MTFs is prolonged 41.9-46.5 fold(15.517-17.2057ns)compared with the pristine powder(0.37ns),and also is prolonged 3 fold(15.517-17.2057ns)compared with the(BNMA-PVS@LDH)n UTFs(4.61-5.03ns).Comparing with(MMT/BNMA@PVA)n MTFs,the lifetime of(MMT/BNMA@PVA/LDHs/BNMA@PVA)n MTFs is higher,especially when n is lower than 16.These results can be expected that the inorganic nanosheets provide BNMA with a rigid and ordered micro-environment,reducing the energy transfer between adjacent chromophores,and the electronic field environment have effective influence on enhancing lifetime of chromophore of BNMA,because the existence of electronic field makes electrostatic interaction between BNMA and nanosheets much stronger.