Design Synthesis And Functionalization Of Siloxane-based Porous Organic Polymers

As an important subclass of porous organic polymers?POPs?,hypercrosslinked porous polymers?HCPs?are produced by knitting rigid aromatic building blocks with external crosslinkers via Friedel-Crafts reaction to forming topological structure in porous materials.In recent decades,HCPs have made remarkable progress in the fields of gas adsorption and storage,drug delivery,heterogeneous catalysis and organic pollutant treatment due to the advantages of stable physicochemical properties,high specific surface area and permanent pore structure.Phenylsiloxane compounds?OSC?are a kind of rigid building block with Si-O-Si structure,which are easy to be chemically modified.Because of its excellent thermal stability and chemical reagent resistance,it is widely used in the fields of fiber,rubber,resin and other materials.The adjustable Si-O-Si structural units between the rigid structures make the HCPs based on PSC have the advantages of stable thermodynamic properties and abundant micropores.In this work,three kinds of phenylsiloxane compounds with different sizes were designed and synthesized,and a series of new siloxane HCPs were synthesized by using them as monomers.Firstly,a series of siloxane-based HCPs were synthesized by Friedel Crafts reaction using the siloxane compounds and appropriate cross-linkers?such as formaldehyde dimethyl acetal,1,3,5-trichloro-2,4,6-triazine,etc.?.The synthesized siloxane monomers have great differences in molecular chain length and structure,which are reflected in HCPs materials.By studying the differences of HCPs materials formed by different phenylsiloxane monomers in three-dimensional configuration,specific surface area,pore size and other aspects,the internal relationship between the structure of phenylsiloxane and the structure of HCPs materials was explored.Secondly,the Si-O-Si bond in the porous polymer structure was broken by alkali treatment to remove the uncrosslinked-O-Si?CH₃?₂-O-structure.And the effects of cross-linking degree and rigidity of crosslinker on the pore structure of alkali treated HCPs were explored.Then,further acid treatment formed new porous polymers with Si-OH groups in the structure.And the existence of these functional groups provides the possibility for the functionalization of HCPs by the reaction of Si-OH groups and silane coupling agents with different functional groups.Finally,HCPs are used in the fields of water treatment,heavy metal ion capture and chiral separation.At the same time,the effect of pore size of siloxane-based HCPs on the adsorption of organic dyes and the reasons for the influence on the adsorption capacity were explored.In conclusion,the systematic study of siloxane-based HCPs pore size adjustment and functional modification in this work provides a new strategy for the functionalization and application of HCPs.