Oxford Instruments Asylum Research is pleased to announce an online virtual symposium on Applications of Atomic Force Microscopy in Polymer Research. The symposium will feature a panel of experts who will describe the role of atomic force microscopy in their research projects and share recent results. Individual Q&A sessions after each presentation and a panel discussion will allow attendees to address questions to the speakers.
Register now! You will receive an email confirmation of your registration from which you can add the event to your calendar to save the date.
Wednesday, October 27th, 2021
7-9 am PDT (14:00-16:00 UTC)
University of Chicago
Dr. Richard Sheridan
Dr. Kenneth Strawhecker
U.S. Army Research Laboratory
Julia Murphy is currently a doctoral candidate under the advisement of Prof. Steven Sibener at the University of Chicago. Her research focuses on the self-organization and surface dynamics of polymer thin films in confinement using in situ AFM. She received her B.S. in Chemistry from the University of Alabama in 2016.
Understanding the dynamic properties and organization of polymeric thin films is critical for achieving perfection in polymer nanopatterns, a goal for fundamental science as well as technology applications. The Sibener group uses environmentally controlled atomic force microscopy (AFM) to examine the mobility of these films in elevated temperatures above the glass transition temperature and in liquid environments. In this talk, I will present recent work on in situ AFM studies of swollen terraced poly(styrene-block-methyl methacrylate) (PS-b-PMMA) thin films under cyclohexane. We observe high anisotropic swelling of the polymer network, leading to softer terraces that become sensitive to damage from the AFM scanning probe. Additionally, we determined the swelling dynamics are mediated by the chain relaxation rate, as indicated by the propagation of swelling from the terrace step edges via a sharp solvent front. Next, I will discuss experiments using temperature-controlled AFM to directly capture the dynamics of topographically confined cylinder-forming PS-b-PMMA. The confinement drives linear alignment of the polymer domains and, in combination with the increased time resolution from disabling the slow-scan axis, allows in situ observation of interfacial fluctuations, pattern roughness, and defect behavior and annihilation. Through confinement in tapered-width lithographic trenches, we examine the pathways by which defects evolve and annihilate during thermal annealing and seek to understand how these structural defects influence thermal fluctuations of the polymer film.
Richard Sheridan is a Research Scientist in the Brinson Advanced Materials Laboratory at the Duke University Department of Mechanical Engineering and Materials Science. Richard received his Ph.D. from the University of Colorado at Boulder for studying the rheology and applications of thermoreversible polymer networks while funded by a GAANN fellowship. He then accepted a postdoctoral position at the National Institute of Standards and Technology (NIST) where he received an NRC Postdoctoral Associateship to research the physics and metrology of polymer films and interfaces. Subsequently, he was funded by Owens Corning and then a NIST-CHiMaD fellowship to measure the interphase of glass fiber epoxy composites and the effect of that interphase on strength and fatigue of fiberglass materials. His current research interests include optimal experimental design, uncertainty quantification, and AI-augmented laboratory techniques, especially in the context of AFM nanomechanics.
Scanning probe microscopy encompasses techniques that span length scales, time scales, and operational complexity scales. Because of the existence and value of these complex measurements, it is typical for an eager, new user to require extended training together with an expert to reliably acquire the advanced, precise data they hope to collect. In our new review in Progress in Polymer Science , we attempt to address the nuances of extended training by providing a resource in the form of a collection of recommendations and best practices in the nanomechanical characterization of polymers and other soft/heterogeneous materials. The review discusses and compares the variety of nanomechanical techniques available, provides details and practical considerations for real nanonomechanical experiments, and summarizes notable published works as case studies for the application of available modes for nanoscale property mapping. This presentation selects a very small subset of the content to demonstrate the utility of the review as a guide, but also to draw attention to some unanswered questions that were raised as this domain continues to mature.
 Collinson DW, Sheridan RJ, Palmeri MJ, Brinson LC (2021) Best practices and recommendations for accurate nanomechanical characterization of heterogeneous polymer systems with atomic force microscopy. Progress in Polymer Science, 101420. https://doi.org/10.1016/j.progpolymsci.2021.101420
Dr. Strawhecker is a Materials engineer at the Army Research Laboratory in the Composite and Hybrid Materials Branch and leads the Multiscale Behavior of Fibers and Textiles portion of the Soldier Materials/Soft Armor Program. His research interests include processing-structure-property-performance relationships for a variety of materials, especially high-performance ballistic fibers. Dr. Strawhecker has co-authored over 35 journal publications and book chapters and contributed to more than 35 conference proceedings. Many of his recent works highlight novel sample preparation and probing techniques which he developed and which are sought by industrial and academic researchers in fiber science towards developing next generation anti-ballistic fibers.
The Army desires to reduce Warfighter burden through increased protective packages. To do so, ballistic fiber and composites processing can be varied to achieve better performance. Sub-fiber structural information is a key detail needed to enrich processing steps. ARL has developed unique techniques to make these fiber morphology measurements and correlate fiber structure to properties. The measurements can be made from the micron to the molecular scale and these results have recently been published for Aramids and UHMWPE. AFM methods to collect and analyze these data will be discussed particularly with respect to processing-structure-property relationships of the high-performance fibers. These measurements will enable performance enhancements and weight reductions in Next Gen lightweight armor packages.
Distribution A: Approved for public release. Distribution is unlimited.