Batch-Scale Preparation And Process Optimization Of Nanoscale Janus Emulsions And Particles Under Mild Conditions

Soft matter refers to the substance between solid and ideal fluid.The typical types of soft matter are gas-liquid,liquid-liquid,or solid-liquid mixture composed of colloid,polymer,surfactant,and biological macromolecule.Janus emulsion is a kind of soft matter,it is a polydisperse system composed of two immiscible liquid phases in the internal phase,the composition,physicochemical properties,and shapes of the compartments in the internal phase are asymmetry.Janus droplets provide a more convenient and flexible platform for the encapsulation and directional delivery of functional materials.The size of nanoemulsion is in the range of 20-500 nm with a narrow size distribution.Nanoemulsion presents a transparent(translucent)emulsion appearance and excellent dynamic stability.In the present thesis,the phase inversion composition method(PIC method)was used to prepare Janus nanoemulsion in batches under mild conditions,and the microstructure of the lamellar liquid crystals during the phase inversion process was studied.The morphology of the emulsion droplet was adjusted by changing the material composition of the Janus nanoemulsion system,and the Janus nanoemulsion was applied to the template for the synthesis of Janus nanoparticles to achieve controllable adjustment of Janus nanoparticles.The preparation of Janus nanoemulsion was usually based on the high-energy method,which has great energy consumption and is not conducive to large-scale engineering applications.The process of preparing Janus nanoemulsion under mild conditions is simple,which can reduce energy consumption to a large extent,and it brings new processes and methods to the engineering field.The specific research contents are as follows:1.PIC method was employed to prepare Janus nanoemulsion of Oleic acid(OA)/Silicone oil(SO)/Polyoxyethylene(20)sorbitan monolaurate(Tween 20)/H2O system under mild conditions and the formation mechanism of Janus nanoemulsion was further explored.The microstructure of lamellar liquid crystals was also studied,and it was found that the addition of OA molecules induces the formation of lamellar liquid crystals,and the relative material ratio of OA and SO affects the size and position of the lamellar liquid crystals regions in the phase diagram.The thickness of the amphiphilic bilayer increases with the increase of SO content,which reduces the structural strength of the lamellar liquid crystals and induces the transformation of the lamellar liquid crystals phase into the isotropic phase.The morphology of Janus nanoemulsion can be successfully adjusted by changing the material composition,it provides more selectivity for obtaining nanoemulsions with different morphologies suitable for production needs in actual engineering production.2.The morphology of Janus nanoemulsion was adjusted by changing the material composition of OA/SO/Tween/H2O system,and it was found that the difference of surfactant structure significantly affected the morphology of Janus nanoemulsion droplets,proposing a further optimization plan for the preparation of Janus nanoemulsion.Combined with phase diagram,polarizing microscope,small-angle X-ray scattering,and rheometer,the influence of surfactant hydrophobic alkyl chain length on the microstructure of lamellar liquid crystals was investigated.The longer the hydrophobic alkyl chain of surfactants,the larger the size of the lamellar liquid crystals region in the phase diagram of the OA/Tween/H2O system.The influence of the hydrophobic alkyl chain of surfactants on the thickness of amphiphilic bilayer of lamellar liquid crystal was studied by fixing the material ratio of Oil/Tween and changing the length of the hydrophobic alkyl chain of surfactants.It was found that the thickness of the amphiphilic bilayer of lamellar liquid crystals mainly depends on the relative molecular mass of surfactant and the relative length of the hydrophobic alkyl chain between surfactant and OA.3.The Janus microemulsion of OA(TPGDA)/SO/Tween 20/H2O system is prepared by dissolving polymerizable monomers(tripropylene glycol diacrylate)and photoinitiators in the OA phase,and Janus particles are successfully prepared by using Janus microemulsion as a template after being irradiated with ultraviolet light.The topological structure of Janus particles can be controlled by changing the material ratio of OA(TPGDA)/SO.Similarly,the Janus nanoemulsion prepared by the PIC method is applied to the synthesis template of Janus nanoparticles,which greatly expands the engineering application of Janus nanoemulsions.The field makes the preparation process of Janus nanoparticles simpler and can realize the controllable adjustment of the Janus particle size in the micro-nano scale in the engineering application field.