Construction Of Supramolecular Nanostructures With Bile Salts Based On Ionic Self-assembly And Their Multifunctional Applications

Ionic self-assembly(ISA),which is based on electrostatic interactions,has opened a powerful and versatile route to create new supramolecular nanostructures and chemical objects with high hierarchies.Due to its advantages of facility,reliability,costsaving,flexibility and universality in supramolecular chemistry,the research scope,the content and achievement of ISA strategy have been enriched.The template of the surfactant self-assemblies in constructing varieties of the functionalized hierarchical micro/nanostructures is widely used.Thus,the combination of the surfactant and opposite charged substrate molecules via facile ISA strategy enables us to develop new hierarchical self-assembly supramolecular nano-material with various structures and functions.This dissertation is made up of four parts as following:Chapter I,the introduction of the research background.The concepts of supramolecular chemistry,self-assembly,ionic self-assembly,the knowledge of'surfactant physical chemistry,and the aggregation behavior of the ionic self-assembly systems mixed with surfactants were all introduced.The objective and the scientific significance of this dissertation are presented at the end of this chapter.Chapter ?,tailoring self-assembly behavior of a biological surfactant(sodium deoxycholate,NaDC)by imidazolium-based surfactants with different lengths of hydrophobic alkyl tails([Cnmim]Br,n=14,12,8,2).The supramolecular nanostructures and properties of NaDC/[Cnmim]Br mixed systems were characterized using TEM,FE-SEM,POM,FTIR,rheological measurements.The results indicated that the long-chain imidazolium-based surfactants([Cnmim]Br,n ? 8)weakened the hydrogel of NaDC and changed it to sol,precipitate,two phase,solution and LLC phases,while C2mimBr strengthened the hydrogel behavior of NaDC and induced the formation of microcrystals.The electrostatic interaction,hydrophobic effect,and geometric packing are the factors to influence the phase behavior and the self-assembly structures of NaDC/[Cnmim]Br mixed systems.Chapter ?,the hierarchical self-assembly of a biological surfactant,sodium deoxycholate(NaDC),and a cationic dye(rhodamine B,RhB)through ionic self-assembly(ISA)opens up potentially useful routes to construct soft materials.The supramolecular nanostructures with high hierarchies can be reversibly switched between microspheres and microcrystals by controlling the ratio of NaDC to RhB and pH.It can be concluded that the interactions between NaDC and RhB were strongly influenced by electrostatic interaction between the-COO" groups of NaDC and-N+ of RhB.The surfactant/dye composite constructed via an ISA strategy,which combines the template of the surfactant with the luminescent behaviour of the organic dye,will enable us to develop new photoluminescent materials and devices in the near future.The robust hierarchical nanostructures of the NaDC/RhB precipitates can also be used to fabricate an anti-wetting surface with a water contact angle above 90°.The ISA strategy could easily be extended to preparing stable hydrophobic functional surfaces from a wide variety of other starting materials.Chapter IV,ionic self-assembly of bundles of ultralong SC/MB nanobelts with enhanced electrocatalytic activity.The bundles of ultralong nanobelts was formed by an anion biological surfactant(sodium cholate,SC)and a cationic dye(methylene blue,MB)through ionic self-assembly approach.The obtained ultralong SC/MB nanobelts possess smooth surfaces,flat end facets and solid internal structure.The shape and length of the bundles of SC/MB nanobelts could be easily controlled by changing the SC concentration,the aging temperature and pH.Moreover,the electrocatalytic properties of the SC/MB nanobelts modified electrode were also investigated and the results indicated that the bundles of ultralong SC/MB nanobelts exhibited efficient electrocatalytic activity towards L-ascorbic acid(AA)oxidation in phosphate buffer solution(pH=7.0).The present work provides an alternative way to design and fabricate the ultralong belt-like structures with tunable sizes using small organic molecules.This system may also open up a way for the design and development of optical and electronic devices in the potential bio-applications and electrocatalyst for fuel cells.