Dr.Js' presentations at MRS 4/6-10/15 spring mtg:
8:00 PM - W5.13
Generation of Long-Lived Room Temperature Phosphorescence Using Organic Exciplex
Tianlei Zhou1, Yue Wang2, Ghassan Jabbour1.
1, , University of Nevada, Reno, Reno, Nevada, United States; 2, Chemistry, Jilin University, Changchun, Jilin, China.
Abstract
Long-lived room temperature phosphorescence (RTP) from metal-free organic material system is very rare due to the very low intersystem crossing rate in organic molecules and long-lived excited triplet state, which can be easily quenched by oxygen and thermal perturbations.
Since the first reports on long-lived emission from pure crystalline organic compounds in 1978, C.S. Bilen1, there has been limited interest in this area. Recent progress in this area indicates the need for specific conditions to observe such long-lived emission.2-5 For example, small organic molecules were shielded by larger molecules in order to have their phosphorescence stabilized and protected from oxygen quenching. Other approaches relied on crystallizing the molecules or mixing them in specific host matrix in order to observe the long-lived phosphorescence.
In this work, we will present an intense long-lived RTP originating from organic exciplex in the absence of phosphorescence protector or stabilizer. The experimental observation indicates that such exciplex is relatively resistant to oxygen quenching. Moreover, the ease of forming such materials system by simple grinding of commercially available organic components is an attractive low cost approach.
8:00 PM - II3.06
Blade Coating Processing of Nanothick Nano-Cellulose Transparent Paper
Tianlei Zhou1, Hyung Woo Choi1, Ghassan Jabbour1.
1, , University of Nevada, Reno, Reno, Nevada, United States.
Abstract
Due to its small fibril dimension, nano-cellulose materials possess unique optical and structural properties.1-4 This has heightened the interest in nano-cellulose due to its potential in various optical, electrical and mechanical applications, to mention a few. The natural abundance of such environment friendly material makes it even more attractive.
Generally, nano-cellulose fibrils are prepared from natural cellulose fibers through chemical and mechanical treatments in aqueous solution. Their dry film is usually obtained by vacuum filtration followed by solvent evaporation. Because of the slow filtration and evaporation rate of water, the entire film preparation takes relatively a long time,which limits the use of such approach in an industrial setting.
This work will present a fast and economic blade coating approach that is potentially useful for industrial mass production of nano-cellulose film. In such approach, nano-cellulose films and their nano-composites of different optical properties were prepared in ca. one hour time, including the preparation period of the materials water suspension (gel). In particular, a film of only 800 nm thick was successfully made, which, to the best of our knowledge, is the thinnest nano-cellulose transparent paper ever reported to date.
This one is not Jabbour but typical of useful sessions
8:00 PM - LL3.06
Ink Composition of PEG Filler Inks for Printed 3D Microfluidic Devices
Owen Hildreth1, Christopher Lefky1, Avinash Mamidanna1, Jignesh Vanjaria1.
1, , Arizona State University, Tempe, Arizona, United States.
Abstract
The ability to directly print a 3D microfluidic device and sensor using the equivalent of a home printer is a very attractive technology for rapidly deploying chemical and biological sensors. One of the challenges of printing a 3D microfluidic device is removing the “filler” material that is used to define the future microfluidic channel. In this work we examine the use of common Poly(Ethylene Glycol) (PEG) ink as a phase-change filler material with Polydimethylsiloxane (PDMS) ink acting as a printed matrix material. The printed PEG is solid near room temperature and undergoes a phase-change at mild temperatures enabling the filler to be simply “pushed” out of the microfluidic device. This ink combination allows us to print a fully functioning microfluidic device from a 3D Computer Aided Design (CAD) file using drop-on-demand printing techniques.
This work examines how PEG and PDMS molecular weight, ink composition, solvent type, print viscosity, jetting parameters, and substrate temperature impact printed feature resolution. Computational models and experiments show how PEG melt viscosity impacts both directly driven flow channel clearing along with pocket clearing where diffusion is required to completely remove the filler material from a “dead-end” reservoir. A simple chemical detector is exampled by printing metal electrodes using metal-reactive inks. Overall, this work demonstrates a simple method to fabricate 3D microfluidic devices using readily available drop-on-demand printing techniques and helps bring the concept of at-home device fabrication one step closer to reality.
