Microfluidic elaboration of polymer microfibers from miscible phases: Effect of operating and material parameters on fiber diameter

Abstract

Backgroundfiber diameter is one of the most important morphological parameters which drives the applications of microfibers. This creates a need for the development of processes capable of producing a large variety of microfibers with a given diameter. To this regards, microfluidic spinning has recently emerged as an outstanding and simple technique for the production of micro- and nanofibers with controllable size and morphology. Methodsherein, microfibers were produced from (macro)monomers or prepolymers (core phase) by in situ photoirradiation using a capillary-based microfluidic device and a miscible sheath phase of various viscosity. The effects of the flow rate of both phases as well as the viscosity of the sheath fluid, the capillary dimensions and the monomer volume fraction in the core phase were thoroughly studied. Significant findingsby calculating the capillary number ratio from the ratios of sheath to core flow rate and viscosity, an empirical relationship which perfectly predicts the microfiber diameter as a function of monomer volume fraction, the capillary number ratio and capillary inner diameter but independent of its outer diameter is extracted. This result paves the way to the continuous-flow production of microfibers with well-controlled morphological characteristics.