Study On The Pore Structure Control And Properties Of Polyamine Bridged Polysilsesquioxane Materials

Bridged polysilsesquioxane?BPS?is a new type of hybrid material with flexible structure,which has great application value in the field of adsorption and separation.When the bridging group in its monomer molecule is a flexible long chain,the monomers easily entangle with each other during t he gel formation to form a non-porous product,thereby limiting its use as an adsorbent material.In this paper,two bridging monomers,B-DETA-m and B-EDA-m,were synthesized by reacting CPTS with DETA and EDA respectively.The pore structure of the BPS material obtained by the polycondensation of the two monomers was performed by different methods.First,TEOS and porogens?including CTAB and P123?were added during monomer polycondensation to assist in the construction of porous frameworks for adsorbent materials.The effects of the length of the organic bridge,the type of porogen,and the amount of TEOS used on the pore structure of the product were investigated.The structure of the product was characterized by FT-IR,pore size analysis,TEM,XRD and field emission SEM.The results show that the synthesized BPS materials are porous and we have initially prepared samples with nitrogen-containing functional groups.The study on the material adsorption performance shows that the product has good adsorption properties for Au?III?and Ag?I?.Then,on the basis of the above-mentioned bridged monomers,a series of porous BPS materials were synthesized through metal ion?Zn?II?and C u?II??assisted pore formation.The results of pore size analysis proved that the addition of Zn?II?and Cu?II?contributes to the pore structure of the material,and C u?II?is more effective than Zn?II?in the pore formation.After TEOS was added,the specific surface area of the material also increased significantly.The results of the adsorption performance of the as-synthesized samples show that the adsorption capacity of the EDA series samples is higher than that of the DETA series,and the adsorbent material can be in the presence of Pb?II?,N i?II?,Cd?II?,and Ag?I?ions.Selective adsorption of C u?II?,Au?III?and Zn?II?.In addition,different proportions of CTS were introduced into BPS to obtain a series of snake cage composites.FT-IR analysis showed that the intensity of the absorption peak at 3355cm^-1 and 3354cm^-1 gradually increased with the increase of chitosan content,indicating that the NH-containing material was increased,which proved the successful introduction of CTS.N itrogen adsorption and desorption curves indicate that the samples all belong to the macroporous structure.The addition of chitosan can increase the specific surface area of the material and increase the pore size.CTS/BPS snake cage composites have better adsorption properties for Au?III?.Among them,DETA series materials have higher adsorption capac ity for Au?III?than EDA series,and sample DETA/CTS-30 has the largest adsorption capacity,which is as high as 1.8mmol/g.