Microfluidic Fabrication And Structures Control Of High Viscous Polymer Based On Microfluidic Technology

Polymer microparticles play an important role in daily life.The material and the structure of polymer microparticle determine its function.Thus,research of formation and structures control of polymer microparticles have great significance in many practical applications.Microfluidic device is widely used in fabrication of polymer microparticles because of its advantages in accurately controlling liquids in micro scale.However,it is very difficult for the microfluidic technology to make uniform microparticles from high viscous polymer solutions.In this thesis,formation and structures control of high viscous polymer microparticles are studied in order to solve current technique difficulties.First,phase inversion technology was used to fabricate high viscous droplets.Changing the wettability of inner surface of microchannel,changing the surface roughness of microchannel,adding step in the microchannel and adding electro-field into the microfluidic device are used to realize the formation of monodispersed microspheres from high viscous solutions.The maximum viscosity of the monodispersed droplets can be 11.9 Pa·s.Second,controllable phase separation materials system was designed to make microparticles with complex structures.Phase separation in emulsion droplets could spontaneously encapsulate high viscous liquid,forming a high-viscous-liquid-in-polymer structured double emulsion droplet.Porous microparticles with controlled pore size and bowl-shaped microparticles were successfully made through changing the droplet size and the polymerization time.Besides,the evolution law and mechanism of action of the controllable phase separation were studied.Adding nanoparticles into the phase separation system could make it possible to fabricate polymer microcapsules with nanoparticles encapsulated inside.Complex structured microparticles with similar size to human red blood cell were prepared from phase separation solution by high speed stirring using homogenizer.These bowl-shaped microparticles had longer response time in ultrasound field,which may have great significane in anti-cancer drug delivery.Last,separation system containg ZrO₂ sol solution was studied.Temperature,mass-tranfer and polymerization of polymer in the mixture were found to be able to induce the phase separation process.In addition,microparticles with different structures could be made through changing the balance of phase separation process and sol-gel reaction process by changing the emulsion droplet size.ZrO₂ microparticles with different structures were obtained after sintering.