Tuning Curvature in Flow Lithography: A New Class of Concave/Convex Particles

Abstract

Polymeric particles of complex shapes and chemistry have been used for a wide variety of applications in the materials and bioengineering fields. An interesting means of introducing complexity is through curvature. In this work, stop-flow lithography is used to generate concave/convex particles at high throughputs of 3x10(4) particles/h. These particles have finely tuned curvature in the plane orthogonal to the plane of projection of light. The shape in the plane of projection of light is determined by the mask shape. The chemical programmability of this technique is further demonstrated by creating multifunctional particles, i.e., patchy and capped particles. The directed assembly of these particles can find potential application in a variety of fields like biology, photonics, and liquid crystals.

Porous polymer particles—A comprehensive guide to synthesis, characterization, functionalization and applications

“…The shapes and resolution of particles ( Fig. 24(B-D)) achieved with flow lithography techniques [259][260][261][262][263][264][265][266] are certainly unmatched by any other technique. …”

The Synthesis and Assembly of Polymeric Microparticles Using Microfluidics

“…This curvature effect has been exploited by Doyle and coworkers to synthesize 3D particles with concave and convex faces. [66] Multiple immiscible fluids, some of which contained photoinitiator that enabled polymerization and others without photoinitiator that functioned as tuning fluids were used to synthesize particles with tunable curvature by polymerizing across the interface of these coflowing liquids.…”

Hydrogel microparticles from lithographic processes: Novel materials for fundamental and applied colloid science

“…Unlike imprint lithography, the different polymer chemistries need not be immiscible, providing for nearly arbitrary multi-functionality. Furthermore, if the co-flowing precursor streams are immiscible, the interfacial tension between the fluids can be used to induce three-dimensional curvature to the particle shape [60]. Initial studies were limited to co-flowing streams in the plane of the pattern transfer, lowering throughput and limiting chemical anisotropy to “striped” particles [31].…”