Date/Time
Date(s) - 03/11/2021
3:30 pm - 4:30 pm

Dr. Greg Grason – University ofMassachusetts Amherst
(https://www.pse.umass.edu/faculty/researchgroup/grason/research

Date: November 3, 2021

Time: 3:30 PM

Title: Towards programmable self-assembly through geometric frustration

In hardmaterials, geometric frustration (GF) is most often associated with thedisruption of long-range order in the bulk and proliferation of defects in theground state.  Soft and self-assembled materials,on the other hand, are composed of intrinsically flexible building blocks heldtogether deformable and non-covalent forces. As such, soft assemblies systemsare able to tolerate some measure of local misfit due to frustration, allowingimperfect order to extend over at least some finite range. This talk willoverview an emerging paradigm for self-organized soft materials, geometrically-frustrated assemblies (GFAs),where interactions between self-assembling elements (e.g. particles,macromolecules, proteins) favor local packing motifs that are incompatible withuniform global order in the assembly. This classification applies to a broad range of material assembliesincluding self-twisting protein filament bundles, amyloid fibers, chiralsmectics and membranes, particle-coated droplets, curved protein shells andphase-separated lipid vesicles.  Inassemblies, GF leads to a host of anomalous structural and thermodynamicproperties, perhaps most significant, the existence of self-limitingequilibrium states which terminate assembly at finite multi-block dimensions.  I will highlight the some of the basicprinciples and common outcomes GFA, focusing on, in particular morphologicalmechanisms of frustration escape, inwhich assemblies overcome the thermodynamic limits of finite assembly.  I will describe opportunities, challenges andon-going efforts to exploit the scale-dependent thermodynamics of GFA incombination with state-of-the-art approaches to synthesize shape-controlledparticles to engineer new classes of intentionallyill-fitting assemblies that target equilibrium architectures withwell-defined dimensions on length scales that extend far beyond the size of thebuilding blocks or their interactions.

Location: Zoom

Host: Drs. An-Chang Shi & Paul Higgs