Events

We are happy to announce  that since the IPR Symposium originally scheduled on May 6^th had to be cancelled due to Covid-19, and since we do not foresee the possibility of having large gatherings on the UW campus in the Fall term, we have decided to organize a virtual IPR Symposium in the afternoon of Wednesday, September 2^nd, 2020.

Introduction of water-based polyurethane

Abstract

                                               The Hierarchy of Protein Folding

Abstract

Abstract: Some years ago we introduced the concept of fusing rigid 3D molecular building blocks into polymer backbones as a mechanism to create space between polymers. The first systems were conjugated poly(phenylene ethynylene)s with pentiptycene groups, which displayed robust emissive properties in thin films. These systems demonstrated size exclusion properties, amplified sensory responses as a result of excitonic transport, and led to the commercialization of the Fido^TM explosives detectors, which 20 years after their introduction remain the most sensitive portable explosives sensors produced. The critical design principle that the 3D group must be fused within the polymer rather than simply be pendant has become a robust design principle and is fundamental to the design intrinsically porous organic polymers. We have a continuing interest in intrinsically porous polymeric materials, and I will detail our most recent emissive sensors for perfluoroalkyl substances (PFAS) that make use of excitonic transport to create high (ppt) sensitivity. Excitonic transport and the semiconducting properties of these materials need not be limited to sensing applications, and I will detail our demonstrations of the extension to photoredox catalysis. The combination of excitonic and charge (electrons or holes) transport is demonstrated to provide enhanced rates and higher efficiency in these processes.  Catalytic porous organic polymers represent a new approach to heterogenous catalysis; therein the molecular environment can be tailored to meet or exceed the selectivity and activity of homogenous systems. Moreover, they enable the formation of durable catalysis coatings on the surfaces of impellers, glassware, magnetic particles, or tubing for recycling and use in flow reactors.  In addition to photoredox, methods, I will briefly introduce catalytic polymers containing palladium that allow for high activities (>200,000 turnovers/metal center).

Biography: Timothy M. Swager is the John D. MacArthur Professor of Chemistry at the Massachusetts Institute of Technology. A native of Montana, he received a BS from Montana State University in 1983 and a Ph.D. from the California Institute of Technology in 1988.  After a postdoctoral appointment at MIT he joined University of Pennsylvania 1990-1996 and returned to MIT in 1996 as a Professor of Chemistry and served as the Head of Chemistry from 2005-2010.  He has published more than 500 peer-reviewed papers and more than 120 issued/pending patents. Swager’s honors include: Election to the National Academy of Sciences, an Honorary Doctorate from Montana State University, National Academy of Inventors Fellow, The Pauling Medal, The Lemelson-MIT Award for Invention and Innovation, and Election to the American Academy of Arts and Sciences. His research interests are in design, synthesis, and study of organic-based electronic, sensory, energy storage, membranes, liquid crystals, and colloids.  He has founded five companies (DyNuPol, Iptyx, PolyJoule, C­₂ Sense and Xibus Systems).

Ultimately the conformation of macromolecules in solution governs their solution and physical properties. Therefore, polymer scientists must have access to experimental tools capable of probing macromolecular conformations. The current techniques used to characterize macromolecular conformations can be broadly divided into four categories depending on whether they are based on microscopy, computation, scattering, or spectroscopy. Each category of experiments has provided useful insights on macromolecular conformations, but like any experimental method, each one comes with its own set of advantages and limitations.

For example, there exists a wide array of microscopy-based experiments, such as scanning electron (SEM), transmission electron (TEM), atomic force (AFM), etc microscopy, all of which excel at generating images of macromolecules. Depending on the specific instrument, experimental approach, sample type, and preparation applied, different features about a macromolecule can be detected. Microscopy images allow us to predict what conformation a macromolecule will adopt in solution. However, such deductions must be carefully considered since the conformation of a macromolecule adsorbed onto a 2D surface might not be fully representative of the 3D conformation of the macromolecule in solution or in the bulk.

Computation-based experiments, in contrast to microscopy-based experiments, yield 3D macromolecular structures with atomic resolution. The experimentalist imposes the type and length/time scale of interactions, which occur in the system. Consequently, computational methods enable one to account for any interaction which may occur, which is an admirable feature. However, this strength is also a major limitation. Due to the multitude of potential interactions, accounting for all of them in any given system is computationally impossible. Instead, assumptions, custom restraints, and simplifications are required. But since the outcome of these approximations is unknown, they must be benchmarked against experimental data collected from other techniques before being released for wide application.

In comparison, scattering techniques such as small angle X-ray (SAXS), small angle neutron (SANS), and static light (SLS) scattering are well-suited for probing the local density of macromolecules. This, in turn, provides insight on the macromolecules size, shape, and surface. However, scattering experiments typically require high concentrations of monodisperse samples, a feat which can be difficult to achieve for many synthetic macromolecules.

Spectroscopy-based experiments, such as nuclear magnetic resonance (NMR), rely on the ability of a macromolecule to interact with electromagnetic radiation. Specifically, NMR probes the local environment of a given nucleus and its proximity to adjacent nuclei, which, in turn, can be used to generate 3D images of the macromolecular structure. Unfortunately, the minute difference in the local environment experienced by synthetic macromolecules coupled with their broad signals limits the structural information that can be extracted for polymers from NMR experiments. 

The purpose of the present seminar is to discuss the advantages and disadvantages of the current experimental techniques used to probe macromolecular conformations, with an emphasis on their fundamental principles. These advantages and disadvantages will then be compared to those encountered when using pyrene excimer formation (PEF) as a novel methodology for probing macromolecular conformations.

We are excited to announce that this year’s IPR Symposium will be a two day event!  Students and two keynote speakers will present on Day 1 as normal Please find schedule here.  On Day 2 the academic members of the IPR (your supervisors) will be giving a presentation!