2016-2017 Seminar Series

2016-2017 Seminar Series

Abstracts will be added below as they come available:

Our current seminar series planning is as follows:

October 11: Lei Jiang – Chinese Academy of Sciences & Beijing University
2pm, Research Auditorium, NCRC Building 10

October 14: Stephen Cheng – University of Akron
3pm, Room TBD

November 14: Shu Yang – University of Pennsylvania
4pm, Johnson Rooms, Lurie Engineering Center

January 17: Timothy Swager – Massachusetts Institute of Technology
2:30pm, Johnson Rooms, Lurie Engineering Center

February 28: Scott White – University of Illinois Urbana-Champaign
3pm, Johnson Rooms, Lurie Engineering Center


October 11: Lei Jiang – Chinese Academy of Sciences & Beijing University
2pm, Research Auditorium, NCRC Building 10

Smart Interfacial Materials from Super-Wettability to Binary Cooperative Complementary Systems

Learning from nature and based on lotus leaves and fish scale, we developed super-wettability system: superhydrophobic, superoleophobic, superhydrophilic, superoleophilic surfaces in air and superoleophobic, superareophobic, superoleophilic, superareophilic surfaces under water. Further, we fabricated artificial materials with smart switchable super-wettability, i.e., nature-inspired binary cooperative complementary nanomaterials (BCCNMs) that consisting of two components with entirely opposite physiochemical properties at the nanoscale, are presented as a novel concept for the building of promising materials.

The smart super-wettability system has great applications in various fields, such as self-cleaning glasses, water/oil separation, anti-biofouling interfaces, and water collection system.

The concept of BCCNMs was further extended into 1D system. Energy conversion systems that based on artificial ion channels have been fabricated. Also, we discovered the spider silk’s and cactus’s amazing water collection and transportation capability, and based on these nature systems, artificial water collection fibers and oil/water separation system have been designed successfully.

Learning from nature, the constructed smart multiscale interfacial materials system not only has new applications, but also presents new knowledge: Super wettability based chemistry including basic chemical reactions, crystallization, nanofabrication arrays such as small molecule, polymer, nanoparticles, and so on.


October 14: Stephen Cheng – University of Akron
3pm, Room TBD

Precisely Functionalized Molecular Nanoparticles Are Unique Elements for Macromolecular Science: From “Nanoatoms” to Giant Molecules

In this talk, we present a unique approach to the design and synthesis of “giant molecules” based on “nano-atoms” for engineering structures across different length scales and controlling their macroscopic properties. Herein, “nano-atoms” refer to shape-persistent molecular nanoparticles (MNPs) with precisely-defined chemical structures and surface functionalities that can serve as elemental building blocks for the precision synthesis of “giant molecules” by methods such as a sequential click approach. Typical “nano-atoms” include those based on fullerenes, polyhedral oligomeric silsesquioxanes, polyoxometalates, and folded globular proteins. The resulting “giant molecules” are precisely-defined macromolecules. They include, but are not limited to, giant surfactants, giant shape amphiphiles, and giant polyhedra. Giant surfactants are composed of “nano-atoms” tethered with flexible polymer tails of various compositions and architectures at specific sites that have drastic chemical differences such as amphiphilicity. Giant shape amphiphiles are built up by covalently-bonded molecular segments with distinct shapes where the self-assembly is driven by the shape of the molecular segment as well as the chemical interaction. Giant polyhedra are either made of a large MNP or by deliberately placing “nano-atoms” at the vertices of a polyhedron. Giant molecules capture the essential structural features of their small-molecule counterparts in many ways but possess much larger sizes; therefore, they are recognized in some cases as size-amplified versions of those counterparts and often, they bridge the gap between small-molecules and traditional macromolecules. Highly diverse, thermodynamically stable and metastable hierarchal structures are commonly observed in the bulk, thin-film, and solution states of these giant molecules. Controlled structural variations by precision synthesis further reveal a remarkable sensitivity of their self-assembled structures to the primary chemical structures. Unconventional nanostructures can be obtained in confined environments or through directed self-assembly. All the results demonstrate that MNPs are unique elements for macromolecular science, providing a versatile platform for engineering nanostructures that are not only scientifically intriguing, but also technologically relevant.


November 14: Shu Yang – University of Pennsylvania
4pm, Johnson Rooms, Lurie Engineering Center

Foldable and Responsive Soft Metamaterials

Reconfigurable soft metamaterials that can bend, fold, or transform the shape in response to external stimuli have attracted significant interests in design of actuators, sensors, and smart materials and devices. We fabricate a variety of microstructured polymer networks, including tilted and straight polymeric pillar arrays and porous membranes with different size, shape and arrangement from poly(dimethylsiloxane) (PDMS), poly(2-hydroxyethyl methacrylate) (PHEMA) based hydrogels, and epoxy based shape memory polymers (SMPs). By exploiting mechanical instabilities in these material systems, we investigate dynamic tuning of the microstructures in respond to environmental cues, such as pH, heat, light, and mechanical stretching, for potential applications such as tunable dry adhesion, water harvesting, and smart windows.

To control the actuation, we design and synthesize anisotropic materials from nematic liquid crystal monomer (LCM) systems. By introducing strong dipole-dipole interactions in mesogens, we achieve stable nematic phases, strong surface anchoring ability, and fast photopolyemrization. Photopolymerization allows us to directly visualize the LC director field and defect structures by scanning electron microscopy (SEM) in real space with 100 nanometer resolution. Building upon fundamental understanding of surface effects and LCM chemistry, we prepare nematic liquid crystal elastomers (NLCEs) with anisotropic strains by precisely aligning the monomers within the patterned microchannels. Thus, we demonstrate to pre-program the folding of 2D sheets into 3D with various curvatures by embedding cues in surface patterns.


January 17: Timothy Swager – Massachusetts Institute of Technology
2:30pm, Johnson Rooms, Lurie Engineering Center


February 28: Scott White – University of Illinois Urbana-Champaign
3pm, Johnson Rooms, Lurie Engineering Center

 

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