Incorporation Behavior of Nonionic Emulsifiers inside Particles and Secondary Particle Nucleation during Emulsion
Hiroshi Kobayashi1, Toyoko Suzuki1, Amorn Chaiyasat2
1Graduate School of Engineering, Kobe University, Kobe 657-8501, Japan.
Langmuir : the ACS Journal of Surfaces and Colloids
|August 14, 2020
Summary
The nonionic emulsifier Emulgen 911 (E911) incorporates into polymer particles during emulsion polymerization. E911 molecules are absorbed and then partially exit, influencing particle nucleation and size distribution.
Area of Science:
- Polymer Chemistry
- Materials Science
- Surface Chemistry
Background:
- Previous studies noted significant incorporation of Emulgen 911 (E911) in polymer particles from emulsion polymerization.
- Potassium persulfate was identified as a common water-soluble initiator in these processes.
Purpose of the Study:
- To investigate the detailed incorporation behavior of E911 during styrene batch emulsion polymerization.
- To understand the dynamic exchange of E911 between polymer particles and the aqueous phase.
Main Methods:
- Batch emulsion polymerization of styrene using potassium persulfate.
- Seeded emulsion polymerization of styrene with pre-formed polystyrene seed particles.
- Monitoring E911 concentration and incorporation percentage relative to conversion.
Main Results:
- E911 incorporation increased to 18% by 50% styrene conversion, then decreased to 13% at 70-80% conversion.
- Similar dynamic incorporation behavior was observed in seeded polymerization experiments.
- Evidence suggests E911 molecules absorbed into styrene-swollen particles partially desorb into the aqueous medium.
Conclusions:
- E911 exhibits a dynamic partitioning behavior, being absorbed into and desorbing from polymer particles during polymerization.
- Continuous secondary particle nucleation, driven by aqueous E911 concentration above CMC, leads to broad polystyrene particle size distributions.
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