Recent and Upcoming Seminars and Conferences
2022 ISA-institute of Advanced Studies
17:30 - 19:00, July 12, 2022
17:30 - 19:00, July 12, 2022
"Lecture on Polymers and Viscoelasticity - available on zoom"
Speaker Daniel T. Hallinan
Date/time Tuesday, July 12, 2022
Location: https://site.unibo.it/isa/en/events/polymers-viscoelasticity-and-sustainable-energy or: Sala Rossa, Palazzo Marchesini, Via Marsala, 26 - Bologna
2022 APS March Meeting-Chicago
11:00AM - 2:00PM, March 16, 2022
"Modeling Dynamic Swelling of Polymer-Based Artificial Muscles"
Speaker Shefik D. Bowen
Date/time Wednesday, March 16, 2022
Location: McCormik Place Exhibit Hall F1
2022 APS March Meeting-Chicago
8:00AM - 10:48AM, March 18, 2022
"Assessing Effective Medium Theories for Conduction through Lameller Grains"
Speaker Omar Taleb
Date/time Friday, March 18, 2022
Location: McCormik Place W-185A
Abstracts
Thermal Diffusion in Polymer Electrolyte MembranesAuthors: Daniel T Hallinan (Florida State University), Micah Silverman (Florida State University), Kyoungmin Kim(Florida State University), Jesufane (Jenny) Mentor (Nextera Energy)
In most mixtures, a concentration gradient develops in response to a temperature gradient. Steady state is quantified by the Soret coefficient, which is the ratio of the thermal diffusion coefficient to the mutual diffusion coefficient. Polymer electrolytes are an interesting class of materials to study in this regard because they could potentially be used in thermogalvanic cells to convert temperature gradients to electricity. Soret coefficients were measured in thermogalvanic cells with lithium electrodes and a dry polymer electrolyte composed of poly(ethylene oxide) (PEO) and lithium bis‐trifluoromethanesulfonylimide (LiTFSI). Voltage and power were measured in response to temperature gradients. Voltage was used to calculate the concentration gradient (and thereby Soret coefficient). Interestingly, the magnitude of Soret coefficient was similar to that in small‐molecule electrolytes and significantly less than that in neutral polymer blends. Surprisingly, the Soret coefficient of this polymer electrolyte depends on salt concentration. In order to understand the concentration dependence, separate measurements of mutual and thermal diffusion of LiTFSI in PEO-based polymers was conducted with time-resolved infrared spectroscopy. *Supported by the National Science Foundation (NSF) and Florida State University (FSU). *NSF Award
12:27 PM to 12:39 PM Modeling Dynamic Swelling of Polymer-Based Artificial Muscles
Authors: Shefik D Bowen (Florida State University), Daniel T Hallinan (Florida State University)
Polymer-based artificial muscles could potentially replace traditional motors and actuators in applications where weight and flexibility are important, such as soft robotics, active prosthetics, and microfluidics. Material chemistry and muscle geometry are important parameters that impact device performance, e.g. strain, strain rate, lifetime, achievable work, and efficiency. Modeling the rate and degree of swelling of polymer fibers is an essential part of developing materials and designing muscles that perform as desired. This study is motivated by the possibility of significant actuation from twisted and coiled polymer fibers that rely on radial swelling to produce reversible work. An analytical thermodynamic expression (based on Flory-Huggins Theory) was combined with a numerical transport model in order to simulate transient swelling of a polymeric network driven by diffusion and migration. The numerical model evaluates the impact of polymer swelling on transport in polymers directly by locally accounting for the length increase of discrete elements due to solvent presence, which cannot be done analytically. The combined model of transient radial swelling of polymer fibers can be used for parametric studies or analysis of experimental data. This study will aid efforts to identify the best material candidates for practical use as artificial muscle fibers and will help evaluate the geometry needed to achieve device requirements.
This tudy is supported by *NSF Award Abstract # 1735968CREST Center for Complex Materials Design for Multidimensional Additive Processing (CoManD).