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2016 Seminars

In this Section

Spring 2016 Seminars

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Friday, February 12, 2016

3:30 p.m.
Bertrand H. Snell Hall Room 212
Dr. Jason B. Benedict

Deptartment of Chemistry

University at Buffalo, the State University of New York

will speak on

Watching crystals work: Structural dynamics of metal-organic frameworks

Abstract:

Photochromic technologies have the potential to transform traditionally passive materials into active materials which change their chemical or electronic properties in response to light stimulus. New photochromic materials are being synthesized and reported at an extremely rapid rate driven in large part by the numerous potential applications for these advanced materials including molecular switches, sensors, data storage, photomechanical devices and even biological switches. One of the newest emerging applications for photochromic technologies being developed in the Benedict research lab is the development of photo-responsive metal-organic frameworks (MOFs): highly porous crystalline frameworks capable of undergoing structural reorganization upon application of light. The Benedict group is also developing cutting edge in situ X-ray diffraction techniques to study the structural reorganization, both photo-induced and through guest exchange, under ‘real world’ conditions in order to develop a molecular level understanding of the processes that occur within these important materials.

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Friday, February 5, 2016

3:30 p.m.
Bertrand H. Snell Hall Room 212
Dr. He Dong

Dept. of Chemistry & Biomolecular Science

Clarkson University

will speak on

Supramolecular Assembly of Peptidic Biomaterials: From Molecular Design and Understanding to Therapeutics Development

Abstract:

Peptide-based supramolecular assemblies represent an important class of soft nanomaterials with hierarchical structural control down to the molecular level. The well-defined molecular structure plays important roles in regulating supramolecular structure, property and various biological activities. In this seminar, I will discuss two self-assembling systems based on de novo designed peptides and their therapeutic applications. The first system is inspired by amyloid nanofibers. By manipulating the attractive and repulsive force through primary sequence variation, nanofibers were formed with desirable features of controlled assembly, nanostructured dimensions, atomically precise localization of chemical functionality ideal for anisotropic nanocarrier design. In a second example, I will discuss a new design of artificial proteins through self-assembly of a two-component chimeric peptide. The synthetic peptide self-assembled into discrete tetrahedron-like protein nanoparticles driven by a combination of symmetry controlled molecular packing and geometric constraint. These preliminary findings are expected to help establish a fundamental understanding of how molecular design impacts folding and assembly of multi-component peptides. It will also help develop more sophisticated peptide-based molecular toolkits for the construction of discrete protein-like nanoparticles with well-defined molecular pattern, increased complexity and diverse functionality.

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Friday, January 29, 2016

3:30 p.m.
Bertrand H. Snell Hall Room 212
Professor Dan Goia

Dept. of Chemistry & Biomolecular Science

Clarkson University

will speak on

“Room temperature sinetrable silver nanoparticles for printable electronics”

Abstract:

Noble metals nanoparticles are widely used in electronics, catalysis, optics, medicine, biology, thin film solar cells, and transparent conductive coatings. The technological advances of all these applications depend on the ability to control the particles size, size distribution, morphology, internal structure, and surface properties. In this regard, there is a strong interest in developing simple, cost effective, and scalable preparation methods capable of synthesizing materials with characteristics that address the specific requirements of a wide range of practical applications.

Inkjet printable conductive structures based on silver nanoparticles are rapidly integrated not only in the traditional electronic components and devices but also in novel applications in displays, sensors, and solar cells. In the case of flexible or thermally sensitive substrates, lowering the sintering temperature of Ag particles is the main technology driver. For this reason, developing particles that could be consolidated into electrically conductive elements/structures at ambient temperature has been for some time now the ‘Holy Grail’ of the electronic industry. The presentation will give an overview of a new type of silver nanoparticles that can form electrically conductive layers at room temperature. The research strategy used in the development of the particles will be discussed in detail and their unique properties will be reviewed. The ability to generate at room temperature (and matter of minutes) highly conductive patterned layers on various substrates will be demonstrated to the audience. Finally, new and exciting applications in existing and emerging technology fields will be proposed.

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Friday, January 22, 2016

3:30 p.m.
Bertrand H. Snell Hall Room 212
Professor Devon A. Shipp

Dept. of Chemistry & Biomolecular Science

Clarkson University

will speak on

“Polyanhydrides: Versatile Biomaterials for Drug Delivery, Shape Memory Polymers, Self-Healing Materials and Nanoparticles”

Abstract:

Polyanhydrides have found a niche in the degradable polymer field, largely because they often undergo surface erosion, but demanding synthesis conditions have held them back from widespread use. To address this problem, we have developed novel polyanhydrides that are based on thiol-ene ‘click’ polymerization, an easy to conduct step-growth mechanism of polymerization that can be applied to make materials that have relatively uniform network structure. Further, thiol-ene ‘click’ polymerization is robust, can be photo-, redox- or thermally-initiated and may use a wide variety of monomers. Thus, these have real potential in a variety of applications, including orthopedics and drug delivery.

Discussed in this presentation will the be the synthesis of elastomeric and semi-crystalline polyanhydrides that have controllable degradation rates, and how this approach to network polyanhydrides can provide significant flexibility in tailoring characteristics such as crosslink density, functionality and hydrophilicity. In particular, it will be shown that polyanhydrides can be used in applications such as drug delivery, can also behave as shape memory polymers, exhibit self-healing properties and can be produced as nanoparticles.

Professor Devon Shipp (center) with graduate students Olivia Durham (left) and Kelly Tillman (right)

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Friday, January 15, 2016

3:30 p.m.
Bertrand H. Snell Hall Room 212
Jennifer Ritz

PH.D. Candidate

Clarkson University

will speak on

“Investigations into the Synthesis of Thiolate-Protected Metal Nanoparticles”

Abstract:

The two-phase Brust-Schiffrin synthesis was developed in 1994 to produce alkanethiolate-protected gold nanoparticles (1-10 nm) that are dispersible in organic media.  It has since been widely employed for a variety of different metals because the products are typically highly stable, relatively monodisperse, and can be dried, stored, and redispersed without significant change.  In these syntheses, metal halide anions are phase-transferred from water to toluene using the phase-transfer agent tetraoctylammonium bromide, generating an ion-pair complex in the organic phase. This phase is then isolated and thiol ligands are added. Finally, a two-phase reduction process is initiated with the addition of an aqueous solution of sodium borohydride.

Over the years, these nanoparticles have been studied extensively by several groups, but little attention has been paid to developing thorough mechanistic understanding of the relatively complex, three-step syntheses for various metals. As a result, synthetic control is currently lacking. In this seminar, several mechanistic studies into the Brust-Schiffrin synthesis of thiolate-protected Pd nanoparticles will be presented.

Additionally, a novel method for the single-phase synthesis of organosoluble thiolate-protected nanoparticles of several different metals (Au, Pd, Ag) is presented here.  Ion-pair complexes of tetraoctylammonium cation and different metal-halide anions are reacted in toluene with an organosoluble reductant in the presence of alkanethiol. This facile, single-step reaction utilizes stable, well-defined precursor species and yields monodisperse nanoparticles comparable to those produced using the more complicated, multistep, two-phase methods.

Professor Paul Goulet (right) with Ph.D. Candidate Jennifer Ritz

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Friday, January 8, 2016

3:30 p.m.
Bertrand H. Snell Hall Room 212
Professor David Mitlin

Chemical & Biomolecular Engineering and Mechanical Engineering

Clarkson University

will speak on

“Coupling in-situ TEM and ex-situ analysis to understand heterogeneous sodiation of antimony”

Abstract:

We employed an in-situ electrochemical cell in the transmission electron microscope (TEM) together with ex-situ time-of-flight, secondary-ion mass spectrometry (TOF-SIMS) depth profiling, and FIB - helium ion scanning microscope (HIM) imaging to detail the structural and compositional changes associated with Na/Na+ charging/discharging of 50 and 100 nm thin films of Sb. TOF-SIMS on a partially sodiated 100 nm Sb film gives a Na signal that progressively decreases towards the current collector, indicating that sodiation does not proceed uniformly. This heterogeneity will lead to local volumetric expansion gradients that would in turn serve as a major source of intrinsic stress in the microstructure. In-situ TEM shows time-dependent buckling and localized separation of the sodiated films from their TiN-Ge nanowire support, which is a mechanism of stress-relaxation. Localized horizontal fracture does not occur directly at the interface, but rather at a short distance away within the bulk of the Sb. HIM images of FIB cross-sections taken from sodiated half-cells, electrically disconnected and aged at room temperature, demonstrate non-uniform film swelling and the onset of analogous through-bulk separation. TOF-SIMS highlights time-dependent segregation of Na within the structure, both to the film-current collector interface and to the film surface where a solid electrolyte interphase (SEI) exists, agreeing with the electrochemical impedance results that show time-dependent increase of the films’ charge transfer resistance. We propose that Na segregation serves as a secondary source of stress relief, which occurs over somewhat longer time scales.

Professor Mario Wreidt (left) and Professor David Mitlin