Symposium FF03: Building Advanced Materials via Particle-Based Crystallization and Self-Assembly of Molecules with Aggregation-Induced Emission

Qian Chen, University of Illinois at Urbana-Champaign

Direct Imaging of Layer-by-Layer Growth in a Colloidal Nanoparticle Superlattice

Written by Alana F. Ogata

Who doesn’t love a good movie? Qian Chen’s talk was filled with movies at the nanoscale as she presented recent in situ transmission electron microscopy (TEM) studies of nanoparticle superlattices. In situ TEM circumvents the limitations of vacuum-conditions in traditional TEM and enables direct imaging in a liquid cell. Chen utilizes low dose in situ TEM to study the crystallization of nanoparticles during the formation of superlattices. The audience next watches a video of cubic nanocrystals accumulating layer-by-layer at the crystal surface revealing the growing morphology of a superlattice. Beyond watching movies, molecular dynamic simulations reveal a 2-step nucleation mechanism comprised of an amorphous precursor nucleation domain and crystal nucleation within the amorphous precursor. In situ TEM movies are captivating but typically suffer from criticisms that come from electron beam radiation damage and challenges controlling the local environment. Careful optimization of in situ TEM studies presented in this talk, Chen points out, was extensive and detailed in a 75-page supplementary document.

Symposium EN03: Green Electrochemical Energy Storage Solutions—Materials, Processes and Devices

Yunya Zhang, University of Virginia

Converting Eggs to Flexible, All-Solid Supercapacitors

Written by Tianyu Liu

How do you typically enjoy an egg? Hard boil? Blend it with rice? For Yunya Zhang from the University of Virginia, he chose not to eat the egg but transformed it into a functional device—a supercapacitor that can store electrical energy!

Zhang’s supercapacitor was derived from eggs exclusively. The research group synthesized graphene-like porous carbon sheets by pyrolysis of blends of yolk, white, and shell pieces, blended the yolk and white with potassium hydroxide to solidify the liquid into a gel as an electrolyte, and used a piece of eggshell membrane as a separator. With the electrodes, electrolyte, and separator at hand, the researchers assembled an all-egg-based supercapacitor that could store electricity! Zhang concluded his presentation by acknowledging his PhD advisor, who allowed him to conduct the “crazy” work.

Symposium MS02: Mechanics of Nanocomposites and Hybrid Materials

Qing Hua Wang, Arizona State University

Defect-Mediated Chemical Modification of Semiconducting 2D Metal Chalcogenides

Written by Jahlani Odujole

Qing Hua Wang and her research team were aiming to create nanoscrolls by using a novel functionalization method. Nanoscrolls are less popular than carbon nanotubes, which have gained recent popularity. She presented two videos of movement (at 55 K and 355 K) to demonstrate how functionalization can be used to attach proteins. The researchers determined that a combination of air plasma and water vapor was essential for rolling nanoscrolls onto a SiO2 substrate. Different bonding energies were also observed for different orientations of the crystallographic lattice structure. This research allows for the chemistry of two-dimensional (2D) materials to be used to modify properties. The analysis of defects was presented as a means to characterize and gain a better understanding of 2D materials. The ability to grow chains of molecules form the basis of their future work.

Symposium EN03: Green Electrochemical Energy Storage Solutions—Materials, Processes and Devices

Chuan Xia, Rice University

Direct Electrosynthesis of Pure Aqueous H2O2 Solutions Up to 20% by Weight Using a Solid Electrolyte

Written by Tianyu Liu

Have you used hydrogen peroxide for disinfection and cleaning at home? Where did you get the chemical? From a pharmacy? A technology developed by Chuan Xia and co-workers from Rice University might allow you to make high-purity hydrogen peroxide on-site and on-demand. No more complaining about the traffic jam on your way to pharmacy shops! Xia and co-workers designed an electrochemical cell allowing H2 and O2 gases to react peacefully and produce hydrogen peroxide. O2 stream flowed into the catalyst-loaded cathode of the cell and was reduced to HO2-. H2 gas entered the anode of the cell and was oxidized to H+. These electrochemically generated HO2- and H+ ions met each other in a porous, solid-state electrolyte and yielded H2O2. Xia said that their cell exhibited over 90% selectivity of H2O2, and could convert ~25 vol.% of H2 gas.

Symposium SB09.03/SB06.11.03: Interfacing Bio/Nano Materials with Cancer and the Immune System

David Mooney, Harvard University

Viscoelasticity and Cancer

Written by Alana F. Ogata

Understanding the time-dependent mechanical properties of matrices in the body can reveal important mechanisms in cancer biology. When a cell is placed in a collagen medium, the cell will reach out to grab, pull, and push itself through the matrix, leading David Mooney to hypothesize that mechanical forces can provide feedback to the cell about its environment. Mooney uses alginate hydrogels to effectively decouple key variables, such as stiffness and ligand density, to study viscoelasticity and its effects on cancer cell proliferation. Upon comparison of hydrogels with identical stiffness, cancer cells rapidly proliferate through more viscoelastic gels. When exploring the effects of viscoelasticity on tumor volume in mice, more tumor growth was observed in viscoelastic conditions compared to tumor growth in elastic conditions. Outside of cancer invasion, viscoelasticity also plays a key role in providing mechanical cues to regulate the immune system. Fascinating results from David Mooney’s talk provide insight into how immune cells respond to elastic-to-viscoelastic transitions and how mechanical checkpoints may largely impact the fate of immune cells in tumors.

Symposium EN06: Development in Catalytic Materials for Sustainable Energy – Bridging the Homogeneous/Heterogeneous Divide

Qi Dong, Boston College

Understanding the Role of Electrolyte in Electrochemical CO2 Reduction Reactions

Written by Tianyu Liu

Researchers have unveiled the role of water with different concentrations in electrochemical CO2 reduction reactions (CO2RR). Wait, did you ask what the water concentration mean? I had the same question when Qi Dong from Boston College began to present in the Thursday morning session of Symposium EN06. It turned out that Dong's work was associated with a unique solution system—water-in-salt.

Water-in-salt systems are solutions with highly concentrated salts. The salt concentration is so high that water molecules could be treated as solutes dispersed among salt ions. Utilizing Li-salt-based water-in-salt solutions, Dong and co-workers investigated the reaction kinetics of CO2RR over the Au surface and at different water concentrations. They revealed that the rate-determining step of CO2RR on Au should be the direct transfer of electrons to CO2, rather than proton-coupled electron transfer.

Symposium SB09.03/SB06.11.03: Interfacing Bio/Nano Materials with Cancer and the Immune System

Andres Garcia, Georgia Institute of Technology

Biosynthetic Hydrogels for Islet Engraftment and Immune Acceptance

Written by Alana F. Ogata

Islet transplantation is currently the only promising cure for Type 1 diabetes. However, phase three clinical trials show that grafts last 3-5 years due to immediate islet death upon transplantation and inadequate vascularization for the islets that remain. Andres Garcia demonstrates how hydrogel technology can be engineered for improved immune acceptance of islet grafts and successful islet transplantation. Microgels containing a Fas ligand are produced via microfluidic polymerization and injected into the kidneys of mice. In combination with a dose of rapamycin, over 90% of grafts preform in diabetic mice without any immunosuppression. This promising work has been validated in fully mismatched MHC non-human primate models. Monkeys treated with the hydrogel-FasL technology showed excellent recovery of blood glucose control without the need for chronic immunosuppressants after graft implantation. Hydrogel-FasL technology is now in clinical trials for delivery to clinically relevant sites and shows great promise for enhancing islet translation and curing Type 1 diabetes.

Symposium FF01: Beyond Graphene 2D Materials|EL04: Emerging Chalcogenide Electronic Materials

Dinh Loc Duong, Sungkyunkwan University

Elif Ertekin, University of Illinois at Urbana Champaign

Doping of inorganic semiconductor materials

Written by Tomojit Chowdhury

The choice of dopants in semiconductor materials dictates their key materials properties, such as magnetism. Dinh Loc Duong from the Sungkyunkwan University gave a detailed account of vanadium (V) doped single-layer (3-atom-thick) tungsten diselenide (WSe2), which were characterized by a combination of magnetic force and transmission electron microscopies. In addition, the research group studied the magnetic domain modulation by an electronic gate, which was indicative of gate-controlled magnetic response of the doped materials. While Duong highlighted the importance of doped layered materials, Elif Ertekin of the University of Illinois talked about the influence that dopants/doping level has on bulk telluride-based diamond- like semiconductors (DLS). Ertekin’s group utilized first principle density functional theory (DFT) calculations to “screen” extrinsic dopants, and thereafter carried out experiments to study the new thermoelectric properties of these materials.

Symposium MS03: Mechanics of Nanocomposites and Hybrid Materials

Ara Kim, University of Massachusetts - Amherst

High-Strain Rate Plasticity of Block Copolymer Microspheres Correlating with Microphase Separation

Written by Jahlani Odujole

Motivated by cold-spray additive manufacturing, Ara Kim’s research group examined polystyrene (PS) and polydiomethylsiloxane (PDMS) for their impact behavior. Microparticles were fabricated. The researchers showed that furnaces anneal microparticles. A laser induced projectile test (LIPIT) was also introduced. The collision with the substrate were tracked using a microscope camera on the order of femtoseconds. Four substrates were tested in this process. Pre-impact deformation of the polymer materials occurred. The deformation effect was related to the acceleration. An analysis was done to compare bonding windows and critical velocity. The researchers are able to produce stable annealed microparticles. The goal of this research was to conduct experiments capable of providing information about the relationship between microspheres and their resulting separation.

Joint Symposia: FF01.15.01/FF02.07.01/MS02.08.01

Andre Geim, University of Manchester

Molecular Transport through Two-Dimensional Capillaries

Written by Jahlani Odujole

Nobel laureate Andre Geim introduced his research to the audience in this standing room only event, where he described a simple method for isolating single atomic layers of graphite. The purpose is to observe van der Waal properties of small cavities. For larger channels, flow tends to revert back to Knudsen. Geim presented two test cases for examining particles transport through the graphite capillary. First, he presented a helium gas passing through in a closed system. He then followed up with a discussion about water molecules in the system. For certain sizes below a threshold, water can become non-electric, which has huge implications in the field of flexible and responsive electronics. Although the research is still in the theoretical phase, it sets the framework for a vast array of applications. This is important because it challenges our current understanding of the manner in which molecules travel through certain materials. The system will serve as a fundamental reference for years to come.