title: Synthesis of Fluorophore-Doped Polystyrene Microspheres: Seed Material for Airflow Sensing.
abstract: Kiton red 620 (KR620) doped polystyrene latex microspheres (PSLs) were synthesized via soap-free emulsion polymerization to be utilized as a relatively nontoxic, fluorescent seed material for airflow characterization experiments. Poly(styrene-co-styrenesulfonate) was used as the PSL matrix to promote KR620 incorporation. Additionally, a bicarbonate buffer and poly(diallyldimethylammonium chloride), polyD, cationic polymer were added to the reaction solution to stabilize the pH and potentially influence the electrostatic interactions between the PSLs and dye molecules. A design of experiments (DOE) approach was used to efficiently investigate the variation of these materials. Using a 4-factor, 2-level response surface design with a center point, a series of experiments were performed to determine the dependence of these factors on particle diameter, diameter size distribution, fluorescent emission intensity, and KR620 retention. Using statistical analysis, the factors and factor interactions that most significantly affect the outputs were identified. These particles enabled velocity measurements to be made much closer to walls and surfaces than previously. Based on these results, KR620-doped PSLs may be utilized to simultaneously measure the velocity and mixing concentration, among other airflow parameters, in complex flows.
authors: NASA Langley Research Center , Hampton, Virginia 23681, United States.
authors: Christopher J
authors: CJ
authors: Wohl
authors: NASA Langley Research Summer Scholars (LARSS), NASA Langley Research Center , Hampton, Virginia 23681, United States.
authors: Jacob M
authors: JM
authors: Kiefer
authors: Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University , Blacksburg, Virginia 24060, United States.
authors: Brian J
authors: BJ
authors: Petrosky
authors: NASA Langley Research Center , Hampton, Virginia 23681, United States.
authors: Pacita I
authors: PI
authors: Tiemsin
authors: Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University , Blacksburg, Virginia 24060, United States.
authors: K Todd
authors: KT
authors: Lowe
authors: Department of Aerospace and Ocean Engineering, Virginia Polytechnic Institute and State University , Blacksburg, Virginia 24060, United States.
authors: Pietro M F
authors: PM
authors: Maisto
authors: NASA Langley Research Center , Hampton, Virginia 23681, United States.
authors: Paul M
authors: PM
authors: Danehy
keywords: PSLs; design of experiments; emulsifier-free emulsion polymerization; fluorescent particles; kiton red 620; particle image velocimetry (PIV)