Optofluidic Force Induction for Online Monitoring of Particle Size Distributions in Emulsion Polymerization Reactions

Area of Science:

• Polymer Chemistry
• Materials Science
• Chemical Engineering

Background:

• Real-time particle size distribution (PSD) monitoring is crucial for emulsion polymerization control.
• Conventional offline methods (DLS, TEM, CHDF) lack the dynamic capability for in situ reaction monitoring.
• OptoFluidic Force Induction (OF2i), an optical tweezers technique, has not been previously applied to polymer reaction monitoring.

Purpose of the Study:

• To evaluate the performance of OF2i for online, in situ monitoring of particle size and PSD during emulsion polymerization.
• To assess OF2i's applicability in stirred-tank reactors for both ab initio and semibatch processes.
• To compare OF2i measurements with established offline techniques.

Main Methods:

• Utilized OF2i, an optical tweezers-based technology, for real-time particle characterization within stirred-tank reactors.
• Conducted ab initio and semibatch emulsion polymerizations of styrene and acrylic comonomers.
• Simulated secondary nucleation by sequential seed additions to test OF2i's dynamic tracking capabilities.

Main Results:

• OF2i successfully tracked particle size evolution and PSD dynamics across various reaction stages, including nucleation and growth.
• Accurate PSD measurements were achieved for polystyrene latexes (>180 nm) and (meth)acrylic copolymer systems (>200 nm).
• OF2i data showed consistency with offline methods (DLS, TEM, CHDF), with a temporal resolution of 10 minutes.

Conclusions:

• OF2i provides continuous, high-resolution PSD data without composition-specific calibration, enabling real-time monitoring of transient dynamics.
• The technology offers capabilities for monitoring population shifts unattainable with conventional offline methods.
• OF2i demonstrates significant potential for advancing process understanding and control in emulsion polymerization.