Molecular Characterization of Polymer Networks Polymer networks are complex systems consisting of molecular components. Whereas the properties of the individual components are typically well understood by most chemists, translating that chemical insight into polymer networks themselves is limited by the statistical and poorly defined nature of network structures. As a result, it is challenging, if not currently impossible, to extrapolate from the molecular behavior of components to the full range of performance and properties of the entire polymer network. Polymer networks therefore present an unrealized, important, and interdisciplinary opportunity to exert molecular-level, chemical control on material macroscopic properties. A barrier to sophisticated molecular approaches to polymer networks is that the techniques for characterizing the molecular structure of networks are often unfamiliar to many scientists. Here, we present a critical overview of the current characterization techniques available to understand the relation between the molecular properties and the resulting performance and behavior of polymer networks, in the absence of added fillers. We highlight the methods available to characterize the chemistry and molecular-level properties of individual polymer strands and junctions, the gelation process by which strands form networks, the structure of the resulting network, and the dynamics and mechanics of the final material. The purpose is not to serve as a detailed manual for conducting these measurements but rather to unify the underlying principles, point out remaining challenges, and provide a concise overview by which chemists can plan characterization strategies that suit their research objectives. Because polymer networks cannot often be sufficiently characterized with a single method, strategic combinations of multiple techniques are typically required for their molecular characterization. S. P. O. Danielsen, H. K. Beech, B. M. El-Zaatari, X. Wang, D. J. Lundberg, G. Stoychev, L. Sapir, S. Wang, Z. Wang, T. Ouchi, P. N. Johnson, Y. Hu, S. L. Craig, J. A. Kalow, J. A. Johnson, B. D. Olsen, and M. Rubinstein, Chem. Rev., 2021. Article Link

Tuesday, February 16th, Dr. Darryl Boyd of the US Naval Research Laboratory will present in the Johnson Group Seminar Series, supported by MONET. This seminar is open to all. Attendees need to register here: https://mit.zoom.us/meeting/register/tJUrcu2rrjwjE9DT9aMu31t4vr5CiCaEBMw6 In 1907, the 1st synthetic polymer, Bakelite, was invented by Leo Baekeland. Since that time, synthetic polymers have become ubiquitous in the daily lives of billions of people around the globe due to their wide-ranging properties and utility. In recent years, polymers' environmental and biological dangers have been increasingly made known to both the scientific community and the general public. Despite the awareness of these dangers, the common slime demonstration has remained a staple for those seeking to introduce polymers in educational settings. In this talk, Dr. Boyd will discuss the current state of environmental polymer contamination and propose alternative ways to introduce polymers into STEM education.

Jeremiah Johnson and his team at MIT reports on a simple strategy to access functional MOF NPs in one pot, using a polyMOF ligand that possesses a polymer block for surface functionalization and a coordination block with tunable multivalency for size control. Yuwei Gu, Mingjun Huang, Wenxu Zhang, Matthew A Pearson, and Jeremiah A. Johnson PolyMOF nanoparticles: dual roles of a multivalent polyMOF ligand in size control and surface functionalization Article Link

Members of the MONET team at MIT offer a unifying review of polymer networks and showcase how a deep understanding of structure‐property relationships can lead to advanced networks with exceptional properties. Yuwei Gu, Julia Zhao, and Jeremiah A. Johnson A unifying review of polymer networks: from rubbers and gels to porous frameworks Article Li nk

Members of the MONET team at Duke have teamed up with the Russian Academy of Sciences to present a conceptual framework for adding molecular details of chain extension and force-coupled bond dissociation to the Lake–Thomas model of tear energy in rubbery crack propagation. Shu Wang, Sergey Panyukov, Michael Rubinstein, and Stephen L. Craig Quantitative Adjustment to the Molecular Energy Parameter in the Lake–Thomas Theory of Polymer Fracture Energy Article L ink

Shu Wang, former Craig & Rubinstein graduate student (and founding member of MONET) has received the Henkel Award for Outstanding Graduate Research in Polymer Science and Engineering. The award is given to recognize a graduate student or recent graduate who has completed an outstanding Ph.D. thesis in polymeric research. The award will be presented during at the American Chemical Society National Meeting in Denver, Colorado, August 21, 2024 in the ACS Division of Polymeric Materials Science and Engineering. Congratulations Shu!

Herb Wakefield and Ana Paula Kitos Vasconcelos were part of the Plastic in the Environment: Leaders and Innovators Collaborating from Australia, New Zealand, and United States (PELICANS) program. This was jointly hosted by our fellow Center for Chemical Innovation, NSF Center for Sustainable Polymers (CSP) in collaboration with Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO)

We officially welcome our newest institution to the Center today! Prof. Juana Mendenhall joins from Morehouse College at the start of Year 3. Welcome Juana!

Curt Waltmann has successfully defended his thesis, "Structure and Assembly of Macromolecular Compartments". Congratulations Dr. Waltmann!

Congratulations to Kelsie Wentz and Steven Chapman for being named Arnold O. Beckman Postdoctoral Fellowship recipients! Kelsie's awarded project in the Klausen lab is "Hybrid Inorganic-Organic Polymers with Embedded Silicon Radicals". Steven's awarded project in the Kalow lab is "Photoresponsive Cross-Linkers for Multifunctional Adaptive Materials".

Haley has successfully defended her thesis, "Synthesis, Characterization, and Theory of Polymer Gels to Elucidate Topology-Property Relationships". Congratulations Dr. Beech!

The team had a fantastic meeting in Chicago to present our progress to the review panel. We followed with a day to talk about new collaborative research opportunities.