Uniform Polymer Beads via Cross-Flow Membrane Shear Dispersion
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Solution Overview
Problem
Conventional methods for preparing polymer beads often result in large particle size distributions due to coalescence of suspended monomer droplets, leading to non-uniform bead products.
Innovation Solution
A method involving a metallic membrane with through holes is used to disperse a polymerizable monomer phase into an immiscible suspension phase, applying a shear force perpendicular to the direction of egression to form uniform monomer droplets, which are then polymerized to produce beads with a narrow particle size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional suspension polymerization or jetting methods are used, then polymer beads can be produced, but the particle size distribution becomes large due to coalescence of monomer droplets
Solution Approach 1:
The patent introduces a membrane as an intermediary device between the monomer phase and suspension phase. The membrane with controlled pore sizes acts as a mediator that regulates droplet formation, preventing coalescence by controlling the dispersion process at the interface between phases.
Solution Approach 2:
The patent changes physical parameters including membrane pore size (1-100 μm), phase flow rates, and shear force conditions to optimize droplet formation. By adjusting these parameters, uniform particle size distribution is achieved while preventing coalescence.
2Manufacturing precision
If shear force is applied to disperse monomer phase into suspension phase, then uniform droplet size is achieved, but the process requires precise control of flow rates and forces
Solution Approach 1:
The system utilizes the natural shear force generated by the co-flowing phases themselves to create uniform droplets. The monomer phase and suspension phase, flowing parallel to each other, automatically generate the necessary shear stress at the interface, eliminating the need for external mechanical dispersion devices.
Solution Approach 2:
The patent employs fluid dynamic principles by controlling the flow rates and velocities of the monomer and suspension phases. The hydraulic shear force generated by the co-flowing liquids creates uniform droplet formation without requiring additional mechanical components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method achieves polymer beads with a volume mean particle diameter of 10 to 180 μm and a coefficient of variance of less than 0.15, ensuring exceptional uniformity and minimizing coalescence during the polymerization process.
Implementation Method 1
A shear force is provided at a point of egression of the first volume into the second volume. The direction of shear is substantially perpendicular to the direction of egression of the first volume.
Implementation Method 2
The monomer droplets dispersed in the second volume are then polymerized, forming the desired polymer beads.
Data Source
AI summary
Speriodal polymer beads having a uniform size are prepared by polymerizing uniformly sized monomer droplets formed by dispersing a polymerizable monomer phase over a cross-flow membrane into an aqueous phase. A shear force is provided at a point of egression of the polymerizable monomer phase into the aqueous phase, the direction of shear substantially perpendicular to the direction of egression of the monomer phase. The polymer beads can be employed in applications where beads having uniform diameters of 10 to 180 μm are useful.