Recent and Upcoming Seminars and Conferences
2020 Virtual AIChE Annual Meeting
11 AM, November 17, 2020
11 AM, November 17, 2020
"Effect of Lithium Salt Dissociation on the Ion Transport Properties in Block Copolymer Electrolytes"
Speaker Kyoungmin Kim
Date/time Tuesday November 17th, 2020 11:00 AM
Spring 2020 FSU Chemistry
4 PM, February 20, 2020
"Structure and Dynamics in Polymeric Nanomaterials for Sustainable Energy"
Speaker Daniel Hallinan
Date/time Thursday February 20th, 2020 04:00 PM
Location: Kroto Auditorium, CSL 1003
Hosted By: Dr. Kennemur
APS March Meeting
March 2-6, 2020
Session B70: Polymer Dynamics at the Nano-to Meso-Scale Revealed by X-ray and Neutron Spectroscopy II
11:15 AM to 2:15 PM, Monday, March 2, 2020
11:51 AM to 12:03 PM Length-Scale Dependence of Block Copolymer Segmental Dynamics
Authors: Daniel Hallinan (FSU), Oluwagbenga Iyiola (FSU), Kunlun Hong (CNMS, ORNL), Monojoy Goswami (CNMS, ORNL), Piotr Zolnierczuk (JCNS-SNS, IFJ), Laura-Roxana Stingaciu (JCNS-SNS, IFJ), William Thomas Heller (NSD, ORNL), Kyoungmin Kim (FSU)
This work examines the effect of interface proximity and tethering on polymer segmental motion. Selectively deuterated block copolymers (BCPs) were studied with neutron spin echo (NSE) spectroscopy. A strongly segregated BCP was used as a model system in which a glassy deuterated polystyrene (dPS) block acted as the interface and the dynamics of a rubbery deuterated polyethylene oxide (dPEO) block was studied. The PEO block was selectively protonated as a label to examine the dynamics near the interface in one sample and near the chain end in another sample. A strong slowing of segmental dynamics in the sample with the protonated label tethered directly to the dPS was observed compared to the dynamics of the sample with the protonated label at the chain end, but with an unexpected length scale dependence. The slowing was only observed at length scales significantly larger than the characteristic PEO segment length (1 nm), and the disparity between interfacial and chain-end dynamics grew with increasing length. The novelty of examining polymer chain motion over a wide range of length scales is enabled by NSE of selectively deuterated BCPs and can impact BCP applications including batteries, water treatment, and gas separations.
*NSF Award 1751450
DOE Office of Science
12:27 PM to 12:39 PM Diffusion of Lithium Salt in Block Copolymer
Authors: Kyoungmin Kim (FSU), Micah Silverman (FSU), Daniel Hallinan (FSU)
Salt-doped polymer electrolytes can replace the flammable liquid electrolytes enhancing safety and chemical stability. The challenges to apply the polymer electrolytes to commercial batteries are dendrite formation and the low ionic conductivity. Understanding the ionic transport is essential to design high-performance batteries. Limitations of the conventional electrochemical measurements arise as the system gets complicated. Accurate and straightforward way to measure the transport properties is required. We successfully applied the measurement technique using time-resolved Fourier Transform infrared - attenuated total reflectance (FTIR-ATR) spectroscopy to polymer electrolytes. The diffusion coefficients of lithium salt through a polystyrene-poly(ethylene oxide) block copolymer (SEO) electrolytes were investigated. Since the concentration gradient is the only driving force, the diffusion coefficient could be decoupled with the ionic conductivity and transference number. The results showed non-monotonic dependence of the diffusion coefficient on the salt concentration implying the polymer structure or ion dissociation plays a role in the diffusion in concentrated polymer electrolyte.
*This study is supported by NSF Award # 1804871.