Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session A01: 101 Years of Polymer ScienceInvited Live Undergrad Friendly
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Sponsoring Units: DPOLY Chair: Connie Roth, Emory University |
Monday, March 15, 2021 8:00AM - 8:36AM Live |
A01.00001: Block Polymers: Extraordinary Consequences of a Few Covalent Bonds Invited Speaker: Frank Bates Block polymers are a ubiquitous form of macromolecules, exploited in myriad areas of fundamental research, and increasingly prevalent in commodity and value added commercial products. These materials are formed by linking together two or more homopolymers with covalent bonds, thus producing hybrid materials embodied with physical properties associated with the individual blocks. This lecture will trace the origins of these fascinating compounds, beginning with the discovery in 1956 by Michael Swarc of “living” anionic polymerization; he immediately recognized the potential to synthesize diblock and multiblock polymers, spawning the development of SIS triblock copolymers, marketed as thermoplastic elastomers in the early 1960’s. By the end of that decade experiments had established the basic molecular weight and composition dependence of nanoscale spherical, cylindrical, and lamellar morphologies in diblock and triblock copolymers. Subsequently, the triply periodic gyroid network phase was added to this list of morphologies. Theory soon followed, catalyzed by the seminal work of Helfand and Leibler, culminating today in the remarkably predictive self-consistent field theory (SCFT). The pace quickened as additional blocks were combined together leading to dozens of documented phases in ABC triblock and higher order multiblocks. And recently, Frank-Kasper and quasicrystalline phases have been discovered in compositionally asymmetric diblock copolymers that form nominally spherical particles. Extraordinary advances in controlled polymerization during the past 3 decades (e.g., RAFT, ATRP, ROMP) has enormously expanded the list of polymers that can be coupled together by individual covalent bonds, offering seemingly unlimited possibilities for creating nanostructured materials of unparalleled sophistication. |
Monday, March 15, 2021 8:36AM - 9:12AM Live |
A01.00002: Computer Simulations of Entangled Polymer Melts: From Segmental Dynamics to Viscoelastic Response Invited Speaker: Gary Grest From the first numerical simulations of single polymer chains in dilute solution to current exascale simulations of highly entangled polymer melts, computer simulations have played a critical role in polymer physics. Numerical simulations have provided microscopic insight into macroscopic behavior. Here the potential of computations to polymer physics in the realm of new computer architectures will be introduced in view of the fundamental insight connecting theory and experiments attained thus far. Capturing the wide range of coupled length and time scales that govern the unique macroscopic, viscoelastic behavior of polymers has been one of the major challenges to surmount. Starting with the simple bead-spring models, through atomistically inspired coarse-grained approaches, it is now possible to capture not only the mobility of the chain but also the viscoelastic properties of entangled polymers. With current and future computational resources, numerical simulations will provide the understanding of viscoelastic response and shear and extensional viscosity of entangled melts for complex architectures bridging the dynamics on the length scale of the atomic level with the macroscopic response. |
Monday, March 15, 2021 9:12AM - 9:48AM Live |
A01.00003: Application of Polymer Physics to tissue viscoelasticity: Entangled active matter Invited Speaker: Francoise Brochard-Wyart
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Monday, March 15, 2021 9:48AM - 10:24AM Live |
A01.00004: Progress in understanding entangled polymer dynamics Invited Speaker: Scott Milner The surprising flow behavior of entangled polymer liquids has been of profound interest throughout the history of polymer science. In the last three decades, substantial progress has been made in mechanistic understanding of entangled polymer rheology, based on the tube ansatz. I will summarize the essential physics of the “success stories”: 1) linear dynamic rheology of entangled linear chains, stars, star-linear blends, H-polymers, polydisperse multiply branched chains, and polydisperse linear chains; and 2) nonlinear extensional flow of linear chains and branched polymers. |
Monday, March 15, 2021 10:24AM - 11:00AM Live |
A01.00005: Polymers Science in Modeling Mushy, Squishy Systems Invited Speaker: Anna Balazs Over the last few decades, there has been rapidly growing interest in soft, stimuli-responsive polymeric materials (“mushy, squishy systems”) that exhibit a global response to a local signal. One motivation for creating such polymers arises from a technological need to produce energy efficient devices that can amplify or convert a small-scale input into a large-scale action. Another inspiration for focusing on responsive polymers comes from biology. One of the exquisitely evolved properties of biological systems is the ability to convert local information into a global action. Few synthetic materials can match the ability of biological systems to undergo large-scale, rapid motion in response to local changes. There are a number of design challenges that must be met in order to create such efficient systems. First, the polymeric material must be capable of not only sensing a local signal, but also reacting in a specified manner. Second, the polymers should ideally be capable of transducing one form of energy (e.g., electromagnetic, optical, chemical) into a mechanical action and thus must be “active”. Developing such responsive polymeric materials poses significant and intriguing scientific challenges, and necessitates the development of robust theoretical and computational models for the behavior of active materials systems. A few examples of these kinds of modeling approaches will be discussed, highlighting efforts that are valuable for developments in future technologies, such as soft robotics and autonomously operating devices. |
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