Preparation And Properties Of Temperature-magnetism Dual Response Janus Spheres Based On Microfluidic Technology

Microfluidics is a subject that processes or manipulates small amounts of fluid.Microfluidic technology has many advantages in the preparation of micro-nanospheres.It has gradually become the principal method to fabricate Janus spheres.Janus sphere is composed of two or more different materials.Due to the biphasic properties,Janus sphere has a wide range of applications in many fields.For example,the color anisotropy of the Janus sphere has excellent optical property and the magnetic Janus sphere has the magneto-driven characteristic.However,little research has focused on magnetic-thermochromic Janus sphere.Exploring the magneto-thermochromic coupling mechanism remains a challendge.In this paper,at first,an experimental platform for generating acrylamide droplets and preparing polyacrylamide microspheres was constructed.Secondly,the factors affecting the size of droplets and particles were investigated.Thirdly,polyacrylamide microspheres,thermochromic polyacrylamide microspheres,magnetic polyacrylamide microspheres,and temperature-magnetism dual response Janus spheres were prepared,respectively.Importantly,various properties of multifunctional polyacrylamide microspheres were characterized.Finally,due to the magnetic switch and thermochromism,these Janus spheres could be applied as colorful display by controlling the magnetic field and temperature.The main research contents of this paper are summarized as follows:1.A flow-focusing PDMS microfluidic chip without throat was fabricated by soft lithography method.Based on the microfluidic chip,an easy-to-manage,low-cost platform for generating acrylamide droplets and preparing poly acrylamide microspheres was constructed.The processing platform prepared different size of acrylamide droplets and polyacrylamide particles.Besides,the factors affecting the size of droplets and particles were investigated.When QclQd was constant,as the Qd increased,the length of the droplets and particles gradually decreased.When Qd was fixed,their length gradually decreased as Qc/Qd increased.2.A platform was built for preparing multifunctional polyacrylamide particles.thermochromic materials were introduced to synthesize thermochromic polyacrylamide microspheres.Magnetic polyacrylamide microparticles were prepared by combining Fe3O4 microspheres as building blocks.Temperature-magnetism dual response Janus microspheres were synthesized by utilizing a permanent array.These Janus microspheres had both magnetic and thermochromic properties,and two colors.3.The performance of different multifunctional polyacrylamide microspheres was observed.The colors of mixed Janus microspheres were red,pink,dark blue,light blue and white at 5,15,25,35 and 45 degrees,respectively.Janus microspheres could rotate with the change of magnetic field direction.Based on the magnetic and thermochromic properties of Janus spheres,a temperature-magnetic response display was constructed.We have created a color display by controlling the direction of the magnetic field and the outside temperature.It could show a pattern by controlling the magnetic field,eventually showing "USTC".