A method for preparing monodisperse polymer microspheres by redox-initiated dispersion polymerization
A technology of dispersion polymerization and polymer, which is applied in the field of monodisperse polymer microspheres, can solve the problems of inability to achieve the unity of the yield and morphology of microspheres, excessive nucleation and growth, and uneven microspheres. High yield and morphology, avoid microsphere inhomogeneity, increase the effect of polymerization rate
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Embodiment 1
[0036] Embodiment 1 prepares macromolecule RAFT reagent PAA-TTC
[0037] Acrylic acid (AA) (14.41 g, 200 mmol), DDMAT (0.1826 g, 0.5 mmol), AIBN (8.23 mg, 0.05 mmol) and anhydrous 1,4-dioxane (48.6 g) were added to a 150 mL one-necked flask , [AA] / [DDMAT] / [AIBN]=400 / 1 / 0.1, the solution was degassed with nitrogen for 30 minutes, and then immersed in a preheated oil bath at 70°C for 2 hours, by immersing the flask in ice water , and then expose it to air. The monomer conversion reached 61.8% (1,3,5-trioxane as internal standard, measured by 1H NMR). This polymer was precipitated into diethyl ether and purified by a precipitation / filtration cycle. After drying at room temperature under vacuum, a pale yellow PAA-TTC polymer powder (6.9 g, 47.9%) was obtained.
[0038] The structural formula of PAA-TTC is as follows, the molecular weight is about 17K
[0039]
Embodiment 2
[0040] Embodiment 2 prepares polymer microsphere
[0041] The weight ratio of ethanol / water mixture 40 / 60 (7.2g+10.8g) was introduced into a 25mL round bottom flask as a solvent, then 2.0g of MMA monomer (10wt% relative to the system), 0.30g of stable dispersant PAA-TTC (15% relative to the monomer), 0.005 g of DDMAT (0.25% relative to the monomer), magnetically stirred to dissolve. The reaction mixture was deoxygenated with nitrogen for 30 minutes, and 0.08 g of hydrogen peroxide and ferrous sulfate (4 wt % relative to the monomer, wherein the molar ratio of hydrogen peroxide and ferrous sulfate was 1:1) was added to react for 3 hours. The product is separated by centrifugation, washed with ethanol / water (50 / 50, w / w), and centrifuged repeatedly for 2-3 times. The cleaned product is dried in a vacuum oven. After 24 hours, a white powder will be produced, and then weighed to calculate the conversion rate. The yield is about 87%. The scanning electron micrograph (SEM) of the r...
Embodiment 3
[0042] Embodiment 3 prepares polymer microsphere
[0043] The redox initiation system used in this example is 0.08g hydrogen peroxide and ascorbic acid (4wt% relative to the monomer, wherein the molar ratio of hydrogen peroxide to ascorbic acid is 1:1) and the types and amounts of the remaining reagents and the implementation process are the same as in Example 2 same. The yield was about 84%. The scanning electron micrograph (SEM) of the resulting product is shown in figure 2 , the monodispersity of the obtained polymer microspheres is good, and the particle size of the microspheres is about 800nm.
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