Intensification For Preparation Process Of Oil-in-water Miniemulsion And Its Polymerization Application

Miniemulsions have attracted much attention because of their dynamic stability,small droplet size and long-term stable storage.In particular,the application of miniemulsions as"microreactors"to synthesize polymer-based nano functional materials has broad prospects.At present,miniemulsions are mainly prepared by high energy emulsification and low energy emulsification.However,the high energy emulsification method has some problems such as relatively high energy consumption and high equipment requirements,while the low energy emulsification method has some problems such as long preparation cycle and difficult continuous production.At the same time,the adaptability of the two emulsifying methods to different systems will also be different,so comprehensive comparative analysis is needed to establish an appropriate method.This paper mainly focuses on low energy emulsification process and the problems existing in the preparation of nanometer polypyrrole(PPy),proposes the preparation of different systems of miniemulsions by low energy emulsification method,and uses impact flow and ultrasonic intensifying technology to improve the stability of the system,and then applies the miniemulsions to the polymerization process to improve the electrochemical performance of PPy.The main research contents of this paper are as follows:(1)Cyclohexane/Span 80-Tween 80/deionized water system miniemulsion was prepared by phase inversion emulsification method.According to the change rule of the phase transformation behavior of the system,the optimal process parameters of emulsion preparation were further obtained as follows:The complex ratio of Span 80 and Tween 80 was 1:9,the mass ratio of oil to emulsifier was 2.1:1,the mass ratio of oil to water was 1:10.5,the viscosity ratio of dispersed phase to continuous phase was 0.25,the emulsification temperature was 60?,the emulsification time was 3 h.The particle size of the prepared miniemulsion was 129.1 nm,the PDI was 0.149,and the emulsification index was 100%.The correlation between droplet size D and viscosity ratio?was established as follows:D??^0.24(00.05(0.830 was established:D?u₀^-0.29(00<2.5,R~2=0.9756).It can be seen that droplet rupture will dominate when the initial velocity of impinging flow is lower than 2.5 m/s.Finally,the instability mechanism of the miniemulsion was analyzed.According to the linear relationship between r~3 and t,the instability mechanism of the miniemulsion system was mainly austenization.The austenization rate could be reduced by heating up to improve the stability of the miniemulsion.(2)Cyclohexane/SDBS/deionized water system miniemulsion was prepared by phase inversion emulsification method.According to the change rule of the phase transformation behavior of the system,the optimal parameters of emulsion preparation were as follows:the mass ratio of oil to emulsifier was 7:3,the mass ratio of oil to water was 1:10,the mass ratio of SDBS to n-butanol was 1.5:1.The particle size of the prepared miniemulsion was 377.7 nm,and the emulsification index was 82.4%.Ultrasonic enhancement technology was used to improve the stability of the emulsion,and the correlation formula between droplet size and ultrasonic power and ultrasonic time was established:D?-1.2P(03 was 0.5.In Na₂SO₄ solution of 1 mol/L,the specific capacitance reached 153.4 F/g at the current density of 0.5 A/g,and the specific capacitance retention was 63.6%after 2000 charge-discharge cycles.The PPy prepared by miniemulsion polymerization was compared with that prepared by conventional method.The specific surface area of PPy prepared by miniemulsion polymerization was 79.2 m~2/g,the particle size was uniform,and the specific capacitance was increased by about 10%.