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Continuous EmulsifierFree Emulsion Polymerization
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Title: Continuous EmulsifierFree Emulsion Polymerization
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Continuous Emulsifier-Free Emulsion
Polymerization
- Brian Edwards
- McMaster University, Department of Chemistry
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Contents
- Introduction
- Equipment/Polymerization
- Particle Growth Mechanism
- CEFEP Vs. Multistage Seeding
- Conclusions
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Introduction
- Simple alternative for the production of
mono-disperse polymeric particles in a wider
range of sizes - Larger size mono-disperse particles have been
produced by a multistage seeding process, however
this is - Tedious
- Difficult to control
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Polymerization - Equipment
- Monomer tank
- Water tank
- Reactor
- Condenser
- N2 continuously bubbled through system
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PS/2 DVB - CEFEP
- A. 284 nm at 1.5 h
- B. 442 nm at 6 h
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PS/2 DVB Batch/CEFEP
- 630 nm at 5 h
- B. 1.9 ?m at 14 h
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PMMA/3 mol EGDMA Batch/CEFEP
- A.758 nm at 4.5 h
- B.1.3 ?m at 5.5 h
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CEFEP
- Amount and timing of initiator is significant
- Rate of polymerization particle size
determined by monomer feed rate - Low initiator concentrations function well
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CEFEP Contributions To Polydispersity
- Later addition of initiator
- Excessive initiator
- Increase in polymerization temperature
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CEFEP
- Therefore
- Polymerization rate and initiator concentration
should be monitored - Add initiator only when a significant decrease
in these variables
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Mechanism of Particle Growth
- Oligomeric free radicals
- May terminate - in situ surfactants
- May grow particle precursors decrease in
situ surfactant concentration
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Mechanism of Particle Growth
- CEFEP continues with a core-shell growth
mechanism - Monomer feed rate is slow
- Polymerization occurs in outer shell
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Multistage Seeding Process
- First stage
- B. Second stage
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Multistage Seeding Process
- Third Stage
- B. Fourth Stage
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Multistage Vs. CEFEP
- Larger particle size, however
- Preparation of seed lattice multistage
- Consideration of seed particle concentration
hard to control later in reaction - Phase separation
- Secondary nucleation
- Smaller particle size (Direct CEFEP)
- After particle nucleation, just add monomer
- Need to consider monomer and initiator feed
rates/amounts
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Conclusions
- Simple
- Preliminary batch polymerization can produce
quite large particles - Spherical particles with uniform cross-linking
- Monodispersity is achieved simply maintain
temperature and monomer/initiator amounts/feed
rate
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References
- Li, J.Q. and Salovey, R. J Polym Sci Part A
Polym Chem 2000, 38, 318. - Zou, D., Ma, S., Guan, R., Park, M., Sun, L.,
Aklonis, J.J. and Salovey, R. J Polym Sci Part
A Polym Chem 1992, 30, 137. - Zou, D., Sun, L. and Aklonis, J.J. J Polym Sci
Part A Polym Chem 1992, 30, 1463.
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References
- 4. OCallaghan, K.J., Paine, A.J. and Rudin, A.
J Appl Polym Sci 1995, 58, 2047. - 5. Kim, J.H., Chainey, M., El-Aasser, M.S. and
Vanderhoff, J.W. J Polym Sci Part A Polym Chem
1992, 30, 171. - 6. OCallaghan, K.J., Paine, A.J. and Rudin, A.
J Polym Sci Part A Polym Chem 1995, 33, 1849.
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