| Polydopamine(PDA) is formed through dopamine’s oxidization and spontaneous self-polymerization under alkaline conditions. Polydopamine is able to form on virtually all type of material surfaces due to its excellent adhesive property and consequently it has been a research hotspot in the area of materials chemistry in recent years. Except the strong adhesion property, the merits of PDA are as follows: great chemical stability; simple preparation process; good biocompatibility; extensive material applicability; secondary modification, etc. These properties widen the research scope of PDA in CEC. OT-CEC is an important type of CEC, which is easy to fabricate and possesses high column efficiency. However, low phase ratio and column capacity are the disadvantages of OT-CEC. Therefore, some capillary modification strategies, such as etching, polyelectrolyte multilayer coating, porous polymer and nanoparticle modification have been presented to increase the phase ratio of OT-CEC. Our work develops a series of analytical methods to fabricate novel OT-CEC columns with multiple properties of PDA. Three coating columns with different properties have been prepared and effectively separated alkylbenzenes, aromatic acids, polycyclic aromatic hydrocarbons(PAHs) and nitrophenol isomers, respectively. The thesis mainly consists of five parts just as follows:The first part of this thesis(chapter one) is a reviw about OT-CEC, introduction of PDA and the application research of PDA in OT-CEC.In the second part(chapter two), a novel method for the preparation of permanent OT-CEC columns with high phase ratio based on layer-by-layer(LBL) self-assembly of polydopamine/gold nanoparticles/thiols(PDA/Au NPs/thiols) was developed for the first time. Multiple properties of PDA, including adhesive property to deposit on the capillary surface, metal ions redox property to reduce HAuCl4 to Au NPs, Michael addition reaction toward thiol groups and property of porosity were simultaneously utilized together with LBL self-assembly technique to fabricate PDA/Au NPs/thiols@capillary. This strategy made full use of PDA’s properties, combining the advantages of LBL self-assembly technique and nanoparticles on increasing the phase ratio of OT-CEC. Under optimization conditions, the baseline separation of alkylbenzenes could be easily achieved by our capillary coating column.In the third part(chapter three), a facile and versatile chemical modification approach to achieve controllable and diverse EOF in CE was developed through PDA/PEI co-deposition method, which was also based on multiple properties of PDA, including adhesive property to deposit on the capillary surface, latent reactivity with amine groups, zwitterionic property and property of porosity. The co-deposition strategy can render the hybrid coatings with various surface charge properties. Consequently, various magnitude and direction of EOF could be controlled easily by altering the preparation parameters, including the mass ratio of PDA/PEI and the molecular weight of PEI(including PEI-600, PEI-1800, PEI-10000). By using the co-deposited columns with controllable EOF, controllable elution order and high separation efficiency of aromatic acids compounds were obtained easily.In the fourth part(chapter four), two metal-organic frameworks UiO-66 and MOF-5 are used as the stationary phase for OT-CEC respectively, based on PDA’s adhesive property to deposit on the capillary surface, property of porosity and metal ions chelation property with Zr4+ and Zn2+. Metal-chelating activity of the catechol groups of PDA can drive the growth of MOFs. Consequently, on account of this property, PDA/UiO-66@capillary and PDA/MOF-5@capillary were fabricated successfully, separating polycyclic aromatic hydrocarbons and nitrophenol isomers respectively by combination of molecular sieving effect and other effects.The fifth part(chapter five) summarized the achievements in experimental sections and some improvements which should be done in the future work. |
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