The Construction And Application Of Stimulus-response Lyotropic Liquid Crystals

Stimuli-responsive lyotropic liquid crystal?LLC?can produce changes in the microstructure,physical or chemical properties.Due to its special properties,stimuli-responsive LLCs have been used in many fields.In this thesis,in order to study the nature of the stimuli-responsive LLC,some stimuli-responsive LLC were constructed by surfactants,including temperature response,OA response,and polyphenol response.In order to entrust light response characteristics to the above LLC system,an azobenzene molecule having a double hydrophobic chain was synthesized.The work of this paper is as follows:1.In the early stage of the thesis,a large number of literatures on stimuli-responsive aggregates and LLCs were reviewed,and the mechanism of stimulation responsiveness and the construction method of stimuli-responsive lyotropic liquid crystals were comprehensively understood.It has been found that pH-responsive ordered aggregates need to contain pH-responsive groups?such as carboxyl groups,phenolic hydroxyl groups,hydrogen phosphate groups or amine groups,etc.?;Temperature-responsive ordered aggregates are generally classified into three types:1.aggregates contain temperature-sensitive groups,such as ether group,hydroxyl group and substituted amide bond;2.Hydrogen bonding plays a key role in the formation of aggregates;3.the additives have temperature response;Light-responsive aggregates which needs to contain a photosensitive group?azobenzene,acrylic acid and spiropyran,etc.?.In addition,additives can also affect the structure and physicochemical properties of LLC.Therefore,on the basis of laboratory experiments,it is proposed to select non-ionic surfactants with ether groups to construct lyotropic liquid crystals with temperature response.The effect of additives on the induction of notification liquid crystals was also studied.The photosensitive molecule was synthesized in order to endow the lyotropic liquid crystal with light response characteristics.Therefore,on the basis of the laboratory,it is proposed to select a nonionic surfactant having an ether group to construct LLC having a temperature response.A nonionic substance containing azobenzene was synthesized to study its light responsiveness.2.Polyoxyethylene?EO?nonionic surfactants are usually safe,non-toxic and non-irritating.The dilution of polyoxyethylene?EO?nonionic surfactant mixtures have been studied in depth,but few studies have been carried out at high surfactant concentration.The different systems of Polyoxyethylene-10-oleyl ether?Brij 97?with different Polyoxyethylene sorbitan fatty Acid Esters?Tween?had been carried out.Phase behavior of Brij 97/Tween 20/H₂O,Brij 97/Tween 40/H₂O,Brij 97/Tween 60/H₂O and Brij 97/Tween 80/H₂O systems were studied.In all of them,Lyotropic liquid crystalline and micelles were found.The length of hydrophobic tails affected the region size and microstructure of liquid crystal:The size order of liquid crystal region was Tween 60system>Tween 40 system>Tween 80 system>Tween 20 system;The lattice parameter???order of sample T-20%and T-30%was Tween 60 system>Tween 40 system>Tween80 system>Tween 20 system.The SAXS spectra and rheological studies showed that the stability of liquid crystals decreases with the increase of Tween.The sample T60-55%changed from viscous fluid?25 ^oC?to hexagonal lyotropic liquid crystal?37 ^oC?.The sample T40-D transformed from mixed phase of H₁+Fd3m at 37 ^oC to H₁ at 42 ^oC.3.In this study,oleic acid?OA?was introduced into the Brij 97/Tween 40/H₂O system and it was found that OA induced the formation of Hexagonal and cubic LLC in Brij 97-Tween 40(MS₈₂,MS₆₄,MS₄₆)/OA/H₂O system.LLCwas used to encapsulate curcumin.small angle X-ray scattering?SAXS?was used to investigate the microstructure of curcumin LLC.Phase diagrams showed that the increase of MS reduced the phase transition temperature?T_C?.Particularly,the T_C of sample C₁Cur and C₂Cur were 37.6 ^oC and 35.4 ^oC respectively,near the temperature of the human body.Thus,the shear rheology and SAXS was used to study the structural changes of sample C₁Cur and C₂Cur with temperature.The moduli values of sample C₁Cur and C₂Cur decreased with the increase of temperature,showing various structural strength.Vitro release experiment was used to study drug release kinetics.The release of curcumin from LLC conformed to the concentration diffusion model.Due to a similar a_S,the release of curcumin from sample A₁Cur,B₁Cur and C₁Cur showed similar release behavior under different MS.The release behavior of curcumin had corresponding relationship with the structure of sample C₁Cur and C₂Cur at different temperature.Curcumin exhibited the fastest release rate when the structure of curcumin LLC were destroyed.4.Interaction between Brij97 and NaDC in mixed micelles was studied by surface tension method.Phase behavior for Brij97/NaDC/IPM/H₂O system was investigated at the desire molar ratio of?_NaDC=0.42 and the human body temperature of 37 ^oC.Hexagonal and cubic liquid crystal were found in this system analyzed by small angle x-ray scattering?SAXS?.some factors were changed to affect the rheological properties of liquid crystal.Rheological investigations showed:The higher content of water and lower experimental temperature favored the greater values of shear viscosity and viscoelastic modulus;The sample was closer to the plastic fluid and was more likely to recover from disturbed state to equilibrium state at lower ratio of NaDC;The curcumin and TP can influence the shear viscosity,viscoelastic properties and phase transition temperature,even change the structure of liquid crystal.This supplies a way to adjust rheological properties,structure and even phase transition by altering those factors.5.A light-sensitive substance,C₁₂azoC₁₂,was synthesized and its structure was confirmed by MS and ¹H NMR.UV-visible spectroscopy and dynamic light scattering show that the structure has good light responsiveness,and the structure can undergo reversible transformation of cis-trans structure.Based on those conclusions,C₁₂azoC₁₂can be introduced into the constructed LLC systems to impart photo-response characteristics,and LLC systems can be studied for the protective ability of photosensitive polyphenols.