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2021 Midwest Mechanics Seminar Series: Nanomechanical AFM for structure, properties and data in multiphase polymers

Event Type
Mechanical Science and Engineering
4100 Sidney Lu Mechanical Engineering Building
Apr 19, 2022   4:00 pm  
Professor L. Cate Brinson, Duke University
Amy Rumsey
Originating Calendar
MechSE Seminars


For polymer composites, nanocomposites and polymer thin film systems, the local properties of polymers can be altered by the chemical and physical interactions with substrates and embedded particles over a length scales exceeding 100nm. In order to better understand and design nanocomposites, polymer coatings and electronic components, it is essential to develop better understanding and robust design strategies. Two key missing links are understanding of altered polymer properties near surfaces/particles and ability to quantitatively leverage prior data for these systems, predictively in a robust manner. Therefore there is great interest in utilizing scanning probe methods to quantify the local property changes in the polymer region near surfaces. Additionally, there is great need to harvest, record and be able to learn from the vast amount of data archived in journal articles.

In the first part of this presentation, we will tackle the challenge to use scanning probe methodologies to generate quantitative measurements of local mechanical properties on polymers and soft materials. In multiphase soft materials, local changes in the sample modulus and tip-sample interactions impact the acquired force curves. Secondary effects, such as the ‘substrate effect’, require careful treatment to ensure that measured property gradients are due to changes in polymer structure. Simulations and experiments have been performed to addresses stress field artifacts when indenting near substrates or embedded particles. Simulations of indentations into a rubber interphase demonstrated that structural effects of the particle in an idealized system can be estimated and removed. We developed a ‘master curve’ that approximates the substrate effect and applied it to AFM indentations of rubber – carbon nanocomposites, demonstrating that substrate effects are well predicted by the ‘master curve’ and can be differentiated from bound rubber.

In the second part of this presentation, a new and growing platform for data, analysis tools and simulation portals for polymer nanocomposites will be presented: NanoMine. NanoMine utilizes a robust schema and ontology to hold the data in a software infrastructure with query, visualization and microstructure analysis tools. Case studies are demonstrated which connect the property-structure-property domains through a combination of machine learning and physics-based modeling, demonstrating the ability to identify the most critical features influence properties. Together this work illustrates a new approach to tackle materials design principles for the complex, high dimensional problems inherent in the multi-phase polymer space. 

About the Speaker:

L. Cate Brinson is currently the Sharon C and Harold L Yoh III Professor of Engineering and the Donald M Alstadt Department Chair of the Mechanical Engineering and Materials Science Department at Duke University. After receiving her Ph.D. in 1990 from Caltech, Dr. Brinson performed postdoctoral studies in Germany at the DLR and began her academic career at Northwestern University in 1992, serving in many roles, including as Department Chair for Mechanical Engineering and an Associate Dean in the McCormick School of Engineering. Her current research investigations involve characterization of local polymer mechanical behavior under confinement, nanoparticle reinforced polymers, nano and microscale response of soft biomaterials and additively manufactured polymers, and materials genome informatics research, where investigations span the range of molecular interactions, micromechanics and macroscale behavior. Dr. Brinson has received a number of awards, including the Eringen Medal of SES, Nadai Medal of the ASME, the Friedrich Wilhelm Bessel Prize of the Alexander von Humboldt Foundation, the ASME Tom JR Hughes Young Investigator Award, and an NSF CAREER Award; she is a Fellow of the American Association for Advancement of Science, the Society of Engineering Science, the American Society of Mechanical Engineering and the American Academy of Mechanics; and she served as a member of the Defense Science Study Group. She has given many invited technical lectures on her research and has authored one book and over 170 refereed journal publications. She has over 25000 citations and an h-index of 70 in Google Scholar. Her book has had over 60,000 chapter downloads from the e-version since publication in 2008 and a second edition published in 2015. She is a member of several professional societies, served 5 years on the Society of Engineering Science Board of Directors, including one year as President of the society, and is a founding member of the Materials Research Data Alliance (MaRDA). She has also been an Associate Editor of the Journal of Intelligent Material Systems and Structures and the Journal of Engineering Materials and Technology, served two terms on the National Materials Advisory Board of the National Academies and has chaired two National Research Council studies.

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