Synthesis of Fe3O4/PMMA Composite Latex Particles: Morphology, Nucleation Mechanism, Kinetic Modeling and Application
Date Issued
2004
Date
2004
Author(s)
Wang, Ping-Chieh
DOI
en-US
Abstract
In this work, Fe3O4/poly(methyl mathacrylate)/poly (methyl mathacrylate-co- mathacrylate acid ) (Fe3O4/PMMA/P(MMA-co-MAA) core-shell magnetic composite latex was synthersized by the emulsion polymerization, which included three steps: the first step was to prepare the stable Fe3O4 colloid (ferrofluid). The second step was to synthesize PMMA in the presence of ferrofluid by emulsion polymerization. The third step was to synthesize the PMMA-co-PMAA in the presence of product from the second step.
First, Fe3O4 particles were prepared by chemical coprecipitation. The magnetic properties and particle size of these magnetic fluids, characterized by transmission electron microscopy and superconducting quantum interference device, respectively, indicated the formation of single-domain nanoparticles. Thermogravimetric analysis measurements showed the existence of two distinct populations of surfactants on the particle surface, which suggests the primary and secondary surfactants.
Second, magnetic poly (methyl methacrylate) [PMMA] composite latex was prepared by emulsion polymerization in the presence of ferrofluid, and the ferrofluid was prepared by means of a coprecipitation method. The effects of some polymerization parameters, such as monomer concentration, ferrofluid content, and initiator concentration on the conversion curve and particle size of magnetic composite latex particles were examined in detail. The results showed that two nucleation mechanisms, seeded polymerization and self-nucleation polymerization, would vary with the polymerization conditions. In the monomer rich and less ferrofluid system, self-nucleation of PMMA was dominant over the entire course of emulsion polymerization. In the monomer less and ferrofluid rich system, seeded emulsion polymerization was the main course to form the magnetic composite latex particles. A generalized mathematical model was developed to estimate the variation of particle concentration during the entire course of emulsion polymerization of methyl methacrylate (MMA) with ferrofluid. Two mechanisms for the nucleation and growth of particles throughout the polymerization reaction were discussed: MechanismⅠ－seeded polymerization; and MechanismⅡ－self-nucleation polymerization. Here the self-nucleation included homogeneous nucleation and micelle nucleation. Coagulation between particles, which came from different nucleation mechanisms during the course of polymerization, was considered and included in our model. When appropriate parameters were selected, our model could be successfully used to interpret the variation of particle concentration during the entire reaction. Under different conditions, the rate of polymerization, the number of radicals in each particle, the average molecular weight of polymers, and the rate constant of termination were also calculated. All of them explained the experimental results quite well.
Third, the magnetic PMMA/P(MMA–MAA) core-shell composite polymer latex was synthesized in the presence of Fe3O4 ferrofluid. Certain kinds of fatty acid modified the surface of Fe3O4 particles, and the resulting Fe3O4 ferrofluid acted as seeds in the polymerization process. Adjusting the MAA shell composition could control the amount of COOH groups on the surface of the magnetic core-shell composite polymer particles.
Last but not least, Immuno magnetic latices were derived through the reaction of COOH groups from the magnetic PMMA/P(MMA–MAA) core-shell composite polymer latex with antibodies or streptavidin. The zeta potential indirectly proved the antibodies or streptavidin did bind with magnetic latex. The potential of the immuno magnetic latex in the clinical application of cell separation was evaluated.
Subjects
成核機制
型態
乳膠顆粒
四氧化三鐵
聚甲基丙烯酸甲酯
動力模擬
Kinetic Modeling
Nucleation Mechanism
Morphology
Fe3O4
PMMA
Latex Particles
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-93-F87524015-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):5df6d0922260e9de5284946b8cca129d