Preparation And Structure Evolution Research Of SiO₂-PMMA Core-Shell Nanoparticle Electrospun Membranes

With many advantages of high melting, the outstanding hardness, excellent chemical stability that other organic materials don’t have, the SiO2has been widely used in enhancing composite materials after combining with organic polymer materials. In recent years, due to their unique structure and excellent mechanical and photoelectric properties, inorganic particles/organic polymer nanofibers have promising application in many areas including filtration, drug delivery, sensors, and tissue engineering and energy storage. However, the aggregation of particles in solution and poor interfacial adhesion of nanoparticles with polymer in nanofibers limited the application effect of these fibers. Moreover, the location of nanoparticles in nanofibers was uncontrollable to result in the random absence of particles and non-uniform structure in nanofibers, which affected the morphology and performance stability of these fibers in the application. Therefore, it was very urgent to find a way to precisely control nanostructures of electrospun nanoparticles/polymer nanofibers. In this study, SiO2-PMMA core-shell structure nanoparticles has been prepared by multi-step chemical reactions. On the condition that the spinnability of SiO2-PMMA nanoparticles has been proved by theoretical analysis, SiO2-PMMA nanofibers are prepared via electrospinning, and the influence of different factors on the microstructure of nanofiber has been systematically studied.SiO2nanospheres with the various uniform sizes were, respectively prepared using Stober method, and the SiO2nanospheres will be subsequently amination and bromide in turn, then the PMMA polymer shells with different molecular weights are grafted onto SiO2nanosphere cores by Atom Transfer Radical Polymerization (ATRP) method, accordingly, which are characterized with FTIR, TGA, GPC, SEM and TEM. After grafting PMMA onto SiO2nanosphere, reunion phenomenon will be improved and core-shell structure with SiO2as the core and PMMA as shell is formed, and the longer the ATRP reaction time will result in the thicker the shell thickness.Based on the theory of the principle of electrostatic spinning, analyzing the feasibility of preparing SiO2-PMMA nanofibers directly using SiO2-PMMA nanoparticles without polymer matrix. On the premise of spinnability, the SiO2-PMMA nanofibers are attempted to directly prepared with SiO2-PMMA nanospheres/DMF electrospinning solution, and effects of electrospinning solution concentration, PMMA shell molecular weight and SiO2nanosphere core size on the structure and morphology of obtained nanofibers were systematically investigated. The experimental results prove that the SiO2with bigger particle size is easy to form nanofiber, and is conducive to form necklace-like nanofiber. The spinning solution with smaller concentration will form the smaller diameter nanofiber, and the PMMA grafted onto the SiO2with smaller molecular weight will form the smaller diameter nanofiber also.When all the ingredients are well tailored, SiO2-PMMA nanospheres stacked one-by-one in a line and formed perfect1D necklace-like structures.