Study On Structure And UV Blocking Properties Of Schiff Base/Layers Double Hydroxides Composites

Schiff base compounds have been applied in the fields of catalysis,medicine,environmental protection,batteries,sensor,thermoelectric materials and fluorochromism for its good coordination and cis-trans configuration changing of C=N.The Schiff base was intercalated into the interlayer of LDHs to investigate the effect of Schiff base on the structure transition and its UV blocking properties,which is great theoretical and practical significance for expanding the theory of intercalation of LDHs and the application of Schiff base.In this work,N,N’-bis(salicylidine)-4,4’-diaminostilbene-2,2’-di-sulfonic acid(SDSD)has been synthesized and intercalated into ZnAl-N03-LDHs by ion-exchange method to obtain ZnAl-SDSD-LDHs.UV-Vis and 13C NMR showed the proton transfer of the phenolic hydroxyl groups to N atom,rupture of C=N double bond and formation of stable conjugated structure after the UV irradiation,indicating the excellent UV absorption capacity of ZnAl-SDSD-LDHs.The UV stability of Schiff base has been improved obviously for the good shielding effect of LDHs.Moreover,there is no obvious absorption decline because the absorption value decreased 0.59%after UV irradiation for 15 days.Asphalt was doped with 3 wt%Zn-Al-SDSD-LDHs and the softening point and viscosity were tested compared with the pristine asphalt.It is obviously showed that the anti-ultraviolet aging ability of the modified asphalt was improved as the value of VAI declined from 5.051 to 2.400 and the value of △S declined from 7.1 to 3.1.In addition,4-[(2-Hydroxy-benzylidene)-amino]-benzenesulfonic acid has been prepared in layers of ZnAl-LDHs and MgAl-LDHs to form ZnAl-PASS-LDHs and MgAl-PASS-LDHs.UV-Vis and fluorescence showed that the UV light is converted into fluorescence dissipation.ZnAl-PASS-LDHs and MgAl-PASS-LDHs exhibited an excellent UV absorption capacity.PP was doped with 1 wt%,3 wt%,5 wt%and 7 wt%ZnAl-PASS-LDHs,respectively.Among these materials,PP with 1 wt%ZnAl-PASS-LDHs has the best anti-ultraviolet aging performance.