Events and Talks

Posters

A low environmental impact emulsion process to convert used styrofoam into polystyrene pellets

Presented in March 2025 at the APS March meeting in Anaheim by Cole Shaub

Abstract Body: Melting or burning plastic for recycling consumes energy and generates secondary environmental contamination. This study introduces a simple and energy-efficient recycling process that transforms Styrofoam into solid polymer granules. Stable emulsions are created by mixing polymer solutions in organic solvents with surfactant solutions. After the solvent is removed from the emulsion, a suspension of millimeter-sized clumped polystyrene pellets is obtained. While the underlying principles are straightforward, performing the procedure involves significant technical challenges. The process of shear-induced emulsion, driven by the onset of Taylor instability, is controlled by several physical factors such as the interfacial tension between the polymer solution and the aqueous phase, the selection of solvent and surfactants, the shear rate, and the polymer solution viscosity. The effects of the above control parameters on particle size distribution, long-term stability of the final suspensions, solvent removal from the emulsion, solid content, and final particle size are examined in this study. The energy cost for conventional methods for recycling similar plastics will be compared with that of the reuse of recovered solvent as well as the given shear.

Ultrabroadband Optical Limiting via Reversible Polystyrene Nanoparticle Clouding: Phase Diagram for Laser Intensity andConcentration Thresholds

Presented in March 2025 at the APS March meeting in Anaheim by Jr Perez

Abstract Body: Optical limiting is a critical mechanism in photonic systems, protecting sensitive optical devices by attenuating high-intensity light to prevent damage through decreased light transmission. This study investigates ultra-broadband optical limiting via reversible clouding of polystyrene nanoparticles (196nm, 108nm, 52nm in diameter) in an aqueous medium, induced near the phase separation boundary by optical trapping. Polystyrene particles can exist as a homogeneous one-phase solution where they are uniformly suspended, but near the phase separation boundary, they transition into a heterogenous two-phase system that blocks incoming light. The boundary corresponds to the concentration conditions where particles shift from one-phase to two-phase. Optical trapping via focused electromagnetic radiation locally increases the particle density, driving the system into the two-phase region. This clouding effectively reduces light transmission and is also reversible, with particles dispersing into the one-phase system when optical trapping is removed or if the light intensity is below the threshold. This study aims to construct a phase diagram mapping sufficient laser intensity for the optical trap and the polystyrene mass fraction concentration for effective optical limiting.

Diffusiophoresis of Colloidal Particles in Non-Electrolytic Solutions

Presented in March 2025 at the APS March meeting in Anaheim by Brielle Byerley

Active forces from noises generated by a combination of passive and active stochastic forces on an optically trapped particles

A low environmental impact emulsion process as an alternative to the conventional recycling methods of plastic wastes

Presented March 6, 2024 at the APS March meeting in Minneapolis by Wenhao Qin

Abstract Body: Conventional plastic recycling by melting or burning costs energy and produces secondary contamination. This paper presents a facile and low-energy-impact recycling procedure by converting single-use plastics into colloidal polymer nanoparticles. In this procedure, solutions of these polymers in organic solvents were first made into stable emulsions in surfactant solutions. Removing the solvent from the emulsion then rendered a stable suspension of colloidal nano polymer particles. Although the principles are simple, technical challenges of conducting the procedure abound. Shear-induced emulsion with its process dictated by the onset of the Taylor instability is governed by a few physical parameters, including the viscosity of the polymer solution, the interfacial tension between the polymer solutions and the aqueous phase, and the shear rate; choices of solvents and surfactant are critically important. This study examined the effects of the above control parameters on the final particle sizes, size distribution, solid contents, times required to remove solvents from the emulsion, and the long-term stability of the final latex suspensions. Energy cost, including shear and recovery of the solvents for reuse, will be estimated for comparison with that of conventional methods for recycling similar polymers.

Localized Fluctuations of Microscopic Active Particles in Living Cells

Presented March 6, 2024 at the APS March meeting in Minneapolis by Johanna Harding

Abstract Body: Microscopic active particles move through a combination of thermal Brownian motion and self propulsion. Brownian motion is of interest to researchers of drug delivery, algae growth, and nanotechnology. Experiments to understand active Brownian motion can have trouble knowing how to analyze the data they have, leading to the necessity of simulation.

We assume that the motion will follow the Langevin equation model, which uses the forces we assume are present. We simulated the motion of a 2D active particle in water, both with and without the quadratic potential confinement that mimics the elastic components of the biological environment. The simulation without the quadratic potential allows us to measure the pure active motion. With the quadratic potential we can see the behavior of the active matter when under confinement, the way they are in biological environments.

Using our simulation we can verify our assumption and then use that to begin analyzing our data. Our next steps are to do an experiment for a particle in a viscoelastic medium and then create a simulation to match our experimental data, based on the simulation we made for water.

The Roles of Surfactants in Some Daily Life Examples: Dish-Washing, Food, and Shaving Creams

Presented August 3, 2023 by Otis Opoku

Talks

Xia, S., Shen, C., Harding, J., and Ou-Yang, H. D. (2024) Extracting Active Fluctuating forces from Fluctuating motions of an active particle in a viscoelastic medium in a quadratic confinement. APS.
Jiang, Z., and Ou-Yang, H. D. (2022). Spatiotemporal Evolution of Diffusiophoresis in a 2D Drying of mixed-sized Colloidal Droplet. APS.
Jiang, Z., Valentine, M. Jagota, A. and Ou-Yang, H. D. (2022). Evolution of the Shape and Surrounding Stress-Strain of an Oil Droplet Embedded in a Drying Colloidal Suspension. APS.
Xia, S., Shen, C., Jiang, Z., and Ou-Yang, H. D. (2022). Deconvoluting Fluctuations of the Active Brownian Motion. APS.
Jiang, Z., Shen, C., Li, L., Xu, Y., & Ou-Yang, H. D. (2021). Time evolution of colloidal stratification in a drying droplet. APS.
Joseph Jiang; H Daniel Ou-Yang; Chong Shen; Lanfang Li. (2021). Time evolution of colloidal stratification in a drying droplet. ACS.
R Wong, C Shen, D Ou-Yang. (2021). Clustering and Pair Dynamics of Induced-Charge Electrophoresis Driven Janus Particles. APS.
C Shen, D Ou-Yang. (2021). Extracted Active Fluctuations from an Active-Passive Mixture Reveal the Dynamic Class of Active Materials. APS.
Shen, C., Jiang, Z., Li, L., & Ou-Yang, H. D. (2020, August). Extract active fluctuations from total fluctuations of a confined active Brownian particle. In Optical Trapping and Optical Micromanipulation XVII (Vol. 11463, p. 114631A). International Society for Optics and Photonics.
Li, L., Guo, W., Jiang, Z., Shen, C., Lau, W., & Ou-Yang, H. D. (2020). Structure Instability in Particle Filled Elastomeric Polymer Composite Under Tensile Stress. APS March Meeting.
Jiang, Zhiyu; Li, Lanfang; Shen, Chong; Valentine, Megan; Ou-Yang, HD. "Stress Relaxation of Drying Colloids." APS March Meeting (2020).
Shen, C., Li, L., Jiang, Z., Gilchrist, J., & Ou-Yang, H. D. Extract Non-Thermal Fluctuations from an Experimentally Measured Histogram of a Confined Active Brownian Particle." APS March Meeting (2020).
Li, L., Huang, Y., Jiang, Z., Zhou, C., & Ou-Yang, H. D. Analyzing the Flow Drying Colloidal Suspensions Using Optical Coherence Tomography." APS March Meeting (2020).
Jiang, Z., Shen, C., Li, L., & Ou-Yang, H. D. Stress relaxation of drying colloids measured by oil droplets. ACS Meeting (2020).
Hao Huang and H. Daniel Ou-Yang, "A DEP force spectroscopy method for colloidal nanoparticles," 2016 EPI Annual Review Meeting, Lehigh University, Bethlehem, PA, June 2-3, 2016.
Hao Huang, H. Daniel Ou-Yang, Willie Lau and Mohamed S. El-Aasser, "Capping layer formation and drying vestiges of latex film," 2016 EPI Annual Review Meeting, Lehigh University, Bethlehem, PA, June 2-3, 2016.
Krittanon Sirorattanakul, Hao Huang, Christopher Uhl, and H. Daniel Ou-Yang, "On Determination of Equation of State of Colloidal Suspensions," APS March Meeting 2016, Baltimore, MD, March 14-18, 2016.
Hao Huang, and H. Daniel Ou-Yang, "Dielectrophoresis force of colloidal nanoparticles," APS March Meeting 2016, Baltimore, MD, March 14-18, 2016.
Hao Huang, Eric Daniels, Andrew Klein, Mohamed S. El-Aasser, and H. Daniel Ou-Yang, "Preparation of Artificial Latex by an Emulsion Solvent Removal", IPCG 2015 Polymer Conference, University of New Hampshire, Durham, NH, June 28 - July 3, 2015.
Wei Nie, Ming-tzo Wei, H. Daniel Ou-Yang, Sabrina Jedlicka, Dimitrios Vavylonis, "Dynamics of myosin II organization into corical contractile networks and fibers," APS March Meeting 2014, Denver, CO, March 3-7, 2014.
Jinxin Fu, Yi Hu, Liangcheng Zhou, Min Yao Lim, Melissa Goleb, Qiwen Zhan,H. Daniel Ou-Yang, “Mapping two-dimension trapping potential of nanoparticles in an optical trap,” International Conference on Photonics Solutions, Pattaya, Thailand, 2013. (SPIE Proc. Vol. 8883, 2013).
Ming-Tzo Wei, J. Ng, C. T. Chan, A. Chiou, and H. D. Ou-Yang, " Transverse force profiles of individual dielectric particles in an optical trap,” SPIE Optics Photonics, San Diego, USA, 2012. (SPIE Proc. Vol. 8458, 2012).
Ming-Tzo Wei, and H. Daniel Ou-Yang, "Thermal and non-thermal intracellular mechanical fluctuations of living cells," SPIE Optics Photonics, San Diego, USA, 2010. (SPIE Proc. Vol. 7762, 2010).
Yi Hu, Xuanhong Cheng, and H. Daniel Ou-Yang, "Fluorescence correlation spectroscopy in an optical trap ," SPIE Optics Photonics, San Diego, USA, 2010. (SPIE Proc. Vol. 7762, 2010).
Jingyu Wang, and H. Daniel Ou-Yang, "Optical tweezers as a force sensor for separating dielectrophoresis and AC electroosmosis forces ," SPIE Optics Photonics, San Diego, USA, 2010. (SPIE Proc. Vol. 7762, 2010).
Joseph Junio, and H. Daniel Ou-Yang, "Measurements of charged colloidal bulk moduli using optical bottles," SPIE Optics Photonics, San Diego, USA, 2010. (SPIE Proc. Vol. 7762, 2010).
Joseph Junio; H. Daniel Ou-Yang, "Depletion-driven selective optical trapping in nanoparticle suspensions," SPIE Optics Photonics, San Diego, USA, 2009. (SPIE Proc. Vol. 7400, 2009).
Ming-Tzo Wei, Jack Ng, C. T. Chan, and H. Daniel Ou-Yang, "Measurement of optical binding force between two colloidal particles," SPIE Optics Photonics, San Diego, USA, 2009. (SPIE Proc. Vol. 7400, 2009).
Joseph Junio and H. Daniel Ou-Yang, “Measurements of the compressibility of colloidal suspensions by radiation pressure,” SPIE Optics Photonics, San Diego, USA, 2008. (SPIE Proc. Vol. 7038, 2008).
Joseph Junio, Eric Blanton, and H. Daniel Ou-Yang "The Kerr effect produced by optical trapping of nanoparticles in aqueous suspensions," SPIE Optics Photonics, San Diego, USA, 2007. (SPIE Proc. Vol. 6644, 2007).
Jing Wang, Huseyin Yalcin, Angela Lengel, Corey Hewitt, and H. Daniel Ou-Yang, “Development and applications of an optical tweezer-based microrheometer: case studies of biomaterials and living cells,” SPIE Photonics West, San Jose, USA, 2007. (SPIE Proc. Vol. 6441, 2007).
L.E. Dewalt, Z. Gao, and H.D. Ou-Yang, "Transient polymeric bridging of colloids," Hydrophilic Polymers: Performance with Environmental Acceptance, Advances in Chemistry Series 248, ed. J. E. Glass, 395 (1996).
L.E. Dewalt, K.L. Farkas, C.L. Abel, H.D. Ou-Yang, M.W. Kim, and D.G. Peiffer, "Shear induced structure and dynamics of tube-shaped micelles," Flow Induced Structure in Polymers, ACS Symposium Series 597, eds. A. I. Nakatani and M. D. Dadmun, 263 (1995).
Z. Gao and H.D. Ou-Yang, "Kinetics of grafted chains in polymer brushes," Colloid-Polymer Interactions, ACS Symposium Series 532, eds. Paul L. Dubin and Penger Tong, 70 (1993).
L.E. Dewalt, H.D. Ou-Yang, M.W. Kim, S.N. Liu, D. Pine, P. Dixon, and D.G. Pieffer, "Kinetics of shear induced micellar sssociation," Material Research Society Symposium Proceedings 248, 203 (1992).

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