| Porous polymer films are widely used in separation,energy storage,flexible electronics,and biomedicine to name just a few.The performances of films in these applications depend mainly on the properties of the films,such as order degree of microstructure,pore size,surface amphiphilicity and chemistry,film thickness and so on.As we known,to control of the properties of the films is inevitably associated with the selection of the preparation methods and optimization of the preparation process.As a result,various strategies for preparation of films have been developed,such as interfacial polymerization,self-assembly,Langmuir-Blodgett(LB)technique,matrix modification and so on.As for these methods as above mentioned,polymer films with properties and functions on demand can be obtained via the template method by the design,synthesis and selection of monomers/building units,the selection and control of polymerization/aggregation methods,the optimization of preparation formulation and process.Unfortunately,with the increasing demand for applications,to precisely turn the performance of films,such as porous structure,physicochemical property,homogeneity and mechanical property,was still a pending issue in the field of film science.For example,as for nanofiltration,how to obtain the films combined with high flux and high selectivity is currently facing huge challenges;as for sensing films,there are many unsolved problems such as optical stability,film permeability and reuseage;as for the flexible electronic films,there is a huge gap between the current property of films and that of its practical application,such as how to match the mechanical property and electrical performance,and the fatigue resistance.Our group has always kept on studies of the correlation between the structure of amphiphilic small molecules and the stability of its liquid-liquid interface,and preparation of the hierarchical porous materials by using the corresponding emulsion system as a template.Therefore,on the basis of our research foundation of the design,synthesis,and interfacial behaviors of amphiphilic small molecule,it is expected to make some contributions for the better precise control of the performances of films,such as porous structures,mechanical properties,wettability and surface chemistry.Based on the research status of films and the studies of the interfacial behaviors of amphiphilic cholesteryl compounds in our group,this dissertation is focused on preparation of a series of polymer films via photopolymerization at liquid-liquid interface by using the amphiphilic cholesteryl compound with double bond,triethylene glycol dimethacrylate(TEGDMA)and pentaerythritol tetra(3-Mercaptop-roplonate)(PETMP)as the starting materials.The as prepared polymer films exhibit the transparent and uniform appearance,and the controllable thickness,flexibility,wettability and permeability,indicating a high potential in selective separation.Specifically,the major work was done in the following two aspects:In the first part of the thesis,A series of flexible polymer films were prepared by UV-induced thiol-ene bond polymerization reaction on liquid-liquid interface formed by the amphiphilic cholesterol derivative molecule(compound V)via using TEGDMA and PETMP as crosslinkers,The as prepared films after drying still show the transparent and uniform appearance,as well as self-standing and flexibility.Also,the properties of the films can be controlled by adjusting the content of compound V and crosslinkers.The experiment found that the type of organic solvents as the oil phase play a significant role in the successful preparation of the films,which should be the integrated and uniform film.After optimization,it was found that,the resulting films possess the uniform and completely whole structure when the mixture of dichloromethane and ether was used as the solvents.At the same time,it was demonstrated that an increase in the content of compound V and cross-linkers gives rise to the denser,thicker and the better flexible films with the more hydrophobic surface on oil phase side.In addition,,PVP was used as a porogen for control the porous structure of the films during the film preparation process,and then three different molecular weight PVPs,,were selected,,indicating that the three PVP with the different molecular weights lead to a decrease of the hydrophobicity of the oil phase side of the films,especially PVP K-60 has the most significant effect on the hydrophilic-hydrophobic property of both sides of the resulting films.Besides,the mechanical tests show the good stretchability of the films in the dry state,and the high thermal stability of the as prepared films was confirmed by the TGA tests.The second part of the thesis,the activation,solvent resistance,swelling and permeability of the as prepared porous polymer films were investigated.Firstly,the films were activated by dichloromethane,ethanol andtetrahydrofuran,respectively,wherein ethanol shows the best activation performance.The activation of ethanol caused the clear change in the microstructures and morphology of the films,indicative of production of lots of pores on both sides of the films,It is expected to further improve the permeability of the films.In addition,the tests of organic solvent resistance of the films showed that only dichloromethane had the determined damage of the films,while the no change was observed when as prepared films were immersed into acetone,benzene,toluene,methanol,n-heptane and ether,respectively.Compared with the poor swelling rate in in alkane solvents,the highest swelling rate of films was obtained in ethanol.Finally,the permeability of the films was investigated by measuring the amount of liquids passing thought films.It was found that the films have a good permeability to the three organic solvents(methanol,ethanol,acetone),but no any water is able to pass through the resulting films.Equally importantly,the content of crosslinkers and the addition of PVP had a significant effect on the permeability of the films. |
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