| Self-assembled intelligent wormlike micelles are capable of responding to external stimuli?eg,light,electricity,temperature,etc.?.Though the process of design is simple,which formed of small aromatic compounds and surfactants.However,they possesse many functions and have lots of important potential applications in petroleum industry,biomedicine,and cleaning process drag reduction and other fields.A mong these external stimuli,light has many advantages that other environmental stimuli do not have.Therefore it becoming more and more popular in recent years.This thesis intends to construct a series ofphotoresponsivesmartmicellesbasedonthecationicsurfactant3-hexadecyloxy-2-hydroxypropyltrimethylammonium bromide(R16HTAB)and different aromatic compounds.It was investigated by rheological measurement system,supplemented with UV spectrophotometer,nuclear magnetic,electron microscopy and other techniques.This work will has great significance for the theoretical research and development of photoresponsive worm-like micelles.This thesis is supported by the National Natural Science Foundation of China?No.21073081 and No.21473084?,and the specific work is as follows:?.PhotoresponsivemicellarsystemconstructedbyR16HTABand Na-ortho-methoxycinnamate?NaOMCA?In this part,we reported the rheological properties of the photorheological fluids by using steady state and frequency sweep measurement.The fluids are formed by the cationic surfactant,3-hexadecyl-2-hydroxypropyl trimethyl ammonium bromide(R16HTAB),acommonlyphotosensitivearomaticcompound,sodium trans-ortho-methoxycinnamicacid?trans-NaOMCA?,or R16HTAB/trans-NaOMCA/sodium salicylate?NaSal?.Initially,aqueous mixtures of R16HTAB/trans-NaOMCA or R16HTAB/Na Sal in basic solution are self-assemble into long,wormlike micelles and give the sample a high viscoelasticity.When NaSal?or NaOMCA?was added to the R16HTAB/NaOMCA(or R16HTAB/NaSal)aqueous solution,the viscosity of the mixed solution was reduced.The system containing NaOMCA shows photoresponsive character.Under ultraviolet light,OMCA undergoes a photoisomerization from its trans to its cis form,which changes the molecular packing at the micellar interface.It makes the longer wormlike micelles become shorter and the viscosity was decreased.?.Photoresponsive rheology system constructed by R 16HTAB and hydroxycinnamic acidThis system were constructed by R16HTAB and hydroxycinnamic acid with different positions of the substituents.And the aim was explored the effects of different substituent positions in hydroxycinnamic acid upon rheological behavior of micelles.Rheology was used to test the rheological properties of each system.Quantum chemical knowledge was used to simulate the molecular electrostatic potential of o/m/p-hydroxycinnamic acid.The interaction between surfactant molecules and aromatic small molecules was analyzed and discussed.The results showed that the position of the substituents had a direct influence on the steric hindrance of the aromatic molecules,which affected the self-assembly of the micelles.Flow speed of these three systems were different.In addition,after UV irradiation the degree of viscosity reduction of each system obeys the following rules:p-hydroxycinnamic acid system>m-hydroxycinnamic acid system>o-hydroxycinnamic acid system.?.Photoresponsive micellar system constructed by R16HTAB and azobenzene derivativesBy building a mixed system of R16HTAB and azobenzene-4-benzoic acid,using ultraviolet-visible spectroscopy,nuclear magnetic spectroscopy,and rheology,it was confirmed that after UV irradiation the viscosity of the system was reduced.The reation of that was the isomerization of trans-azobenzene-4-benzoic acid molecule into cis-azobenzene-4-benzoic acid molecule.It caused that the changes of spatial structure,breaking the close packed form between the micelles,then the stacking mode become loose.However,after the visible light irradiation,the viscosity of the system can be restored to the initial state. |
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