Fractal-like polymeric particles and their use in diverse applications
AssigneeNorth Carolina State University
InventorsOrlin D. Velev, Sangchul Roh
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Abstract
Fractal-like polymeric particles having a hierarchical, branched structure are disclosed. The particles have fibers with nanometer-scale diameters on their peripheries, which enables a number of unique and highly desirable properties. The particles are fabricated by a method combining phase separation and shear forces of different solutions, in particular a polymer solution. In addition, the particles may be used as coatings, nonwovens, textiles and viscosity modifiers and adhesives, among other applications.
Claims26
A particle comprising an aggregate of polymer molecules, and having a branched fibrous structure that includes at least a first portion, a second portion and a third portion, each portion individually having a plurality of fibers wherein:
- the first portion comprises a first plurality of fibers having diameters of from about 10 times to about 100 times larger than the fiber diameters of the third portion, wherein the surface area of the first portion constitutes from about 10% to about 40% of the surface area of the particle;
- the second portion comprises a second plurality of fibers extending from the first portion having diameters of from about 5 times to about 10 times larger than the fiber diameters of the third portion, wherein the surface area of the second portion constitutes from about 20% to about 50% of the surface area of the particle;
- and
- the third portion comprises a third plurality of fibers extending from the second portion having diameters of from about 20 nm to about 500 nm, wherein the surface area of the third portion constitutes from about 10% to about 70% of the surface area of the particle.
A method for fabricating a particle comprising an aggregate of polymer molecules and having a branched fibrous structure, the method comprising:
- flowing a dispersion medium through a high shear mixer;
- introducing a precursor solution into the dispersion medium to form a dispersion system comprising the dispersion medium and a plurality of dispersed-phase components of the precursor solution, wherein the precursor solution comprises a polymer dissolved in a polymer solvent at a concentration of from about 3% to about 10% by weight, and the dispersion medium comprises an anti-solvent;
- and
- shearing the dispersed-phase components by flowing the dispersion system through the high shear mixer, wherein the dispersion system has a Reynolds number of about 3,000 or higher, whereupon the particle is formed in the dispersion medium wherein the particle comprises an aggregate of polymer molecules, and has a branched fibrous structure that includes at least a first portion, a second portion and a third portion, each portion individually having a plurality of fibers wherein:
- the first portion comprises a first plurality of fibers having diameters of from about 10 times to about 100 times larger than the fiber diameters of the third portion, wherein the surface area of the first portion constitutes from about 10% to about 40% of the surface area of the particle;
- the second portion comprises a second plurality of fibers extending from the first portion having diameters of from about 5 times to about 10 times larger than the fiber diameters of the third portion, wherein the surface area of the second portion constitutes from about 20% to about 50% of the surface area of the particle;
- and
- the third portion comprises a third plurality of fibers extending from the second portion having diameters of from about 20 nm to about 500 nm, wherein the surface area of the third portion constitutes from about 10% to about 70% of the surface area of the particle.
Dependencies are inferred from the claim text.