Preparation Of Fluorescent Polymer Nanoparticles In Microreactor

Compared with traditional organic dyes and inorganic quantum dots,flourescent semiconductor polymer dots(Pdots)have higher brightness,better photostability and biocompatibility,and demonstrated utility in various fields,such as life sciences.At present,Pdots are mainly prepared by microemulsion method and nanoprecipitation method.The sizes of Pdots still could not be controlled well using the two methods.In this thesis,microfluidics technology was adopted to control precisely the flow pattern and diffusion process in the nanoprecipitaion method to prepare desired controllable Pdots with smaller size and better monodispersity.The main contents of this study are listed as below:1.Fabrication of microchannel reactors.Quartz glass capillaries with different sizes are refabricated and assembled accurately to construct transparent coaxial microreactors.The inner diameters of injection tubes used range from 3 to 15 ?m.The collection tubes have constant diameters of 50 ?m.2.The effects of operation conditions on mixing of fluids in the microchannels.It was found that the two-phase fluids formed an annular flow,and the two-phase interface gradually blured until completely disappeared downstream.The higher flow ratio of outer phase to inner phase leads to a thinner inner jet.When the two-phase flow ratio is constant,the increasing of flow rate will cause the position of the interface disappeared to move toward downstream.3.Computational fluid dynamics(CFD)software,Fluent,was used to simulate numerically fluid flow and diffusion process.The velocity distribution and THF mass fraction at different axial positions under different flow conditions are analyzed.The numerical simulation results agreed well with the experimental data.4.Effects of operation conditions on the size of polymer nanoparticles.The semiconductor polymer was solved in THF and mixed with deionized water in microreactors to prepare nanoparticles.The diameter distribution of the nanoparticles is measured using dynamic light scattering(DLS)technology.The results showed that the flow ratio of deionized water to polymer solution was the key factor affecting the size of the polymer nanoparticles.The higher flow ratio,the smaller polymer nanoparticles.Pdots with smaller size and better monodispersity can be prepared with optimized conditions.