Conjugated polymer brush (CPB) films are more robust and exhibit more vertically aligned polymer chains than their spun-cast analogs. We prepare CPB films of poly(3-hexylthiophene) (P3HT) by coupling an amine-terminated surface (ATS) formed from (3-aminopropyl)triethoxysilane (APTES) on Si/SiO2 to 4-bromobenzoic acid using standard, inexpensive peptide coupling reagents. The resulting terminal bromobenzene is reacted with Pd(PtBu3)2 and immersed in the monomer solution. X-ray photoelectron spectroscopy, spectroscopic ellipsometry and static water contact angle measurements confirm the surface chemistry at each stage of P3HT CPB preparation. Atomic force microscopy(AFM) and UV-vis spectrophotometry indicate that the CPB films prepared by this method exhibit similar morphology and optical properties to those produced from other methods of poly(3-alkylthiophene) CPB film preparation. Variations of the standard approach, such as using a pre-synthesized silane counterpart or with (11-aminoundecyl)triethoxysilane, show comparable film morphologies by AFM. This method is used to produce the first CPB film of poly(3-dodecylthiophene), showing its utility for exploring CPB films of more sterically demanding polymers. Peptide coupling is used to prepare an analogous functionalized thiol for initiating P3HT CPB film growth from Au surfaces, and microcontact printing with this thiol allows preparation of the first patterned CPB film of P3HT. image

Micro/nanoporous thin films of poly(methyl methacrylate) (PMMA) have been prepared by spin-deposition onto Si substrates from solutions of high molecular weight (similar to 996 kg/mol) PMMA and solvent tetrahydrofuran (THF) at a solution concentration of 15.0 mg/ml. Mean pore areas are <0.1 mu m(2) as determined by atomic force microscopy and vary significantly depending on preparation conditions of PMMA/THF solutions. THF is a poor solvent for PMMA using Lewis acid-base and Gutmann's acceptor number theories. We propose that the nature of THF-PMMA interactions in solution produce the porous structure as a result of a complex interplay between the polymer, the solvent, the antioxidant stabilizer butylated hydroxytoluene (BHT), and ambient humidity. Controlling the BHT at concentration ranges between 0 and 1500 ppm and H2O concentrations using a N-2 glovebox and rigorous drying procedures during solution preparation is critical to reproducibly create such nanoporous films. The resulting porous films have similarities to breath features (BF) reported in the literature but lack the highly ordered hexagonal pore structure characteristic of BF films resulting from humidity effects. We have also observed that the color of thin film optical interference effects seen using optical microscopy can be correlated to the size and density of micropores in the cast films. Finally, we propose a model using Lewis acid-base theory to understand the molecular interactions that result in the nanoporous film microstructure.

Submitted for the MAR15 Meeting of The American Physical Society The Utilization of Chloroform Post-Treatment to Improve the Adhesion of Au Thin Films onto PMMA KATHLEEN KRIST1, CHRIS HUGHES, XIAOFENG HU, James Madison University, BRIAN AUGUSTINE, High Point University — The metallization of Au onto plastics is an important processing step in the fabrication of microfluidic devices. While its corrosion resistance and excellent electrical and thermal conductivity make Au a good choice, its inertness results in poor adhesion to polymer surfaces. Previous studies have indicated that exposing commercially available Poly(methyl methacrylate) (PMMA) sheets to chloroform vapor following Au deposition significantly improves adhesion. In this study, we deposited 6 nm of Au onto 1.50 mm thick PMMA and exposed the samples to vapor released from chloroform heated on a hot plate set at 70 ◦C. The force required to remove the Au thin films was determined by placing samples on a polisher spinning at 150 rpm and utilizing UV-VIS spectroscopy to measure the transmittance of 700 nm light through the films to quantify their removal as a function of applied polishing force. The Au thin films were also characterized using AFM. AFM images demonstrated a progressive roughening of the surface corresponding to an increase in applied force. Additionally, these images support a model in which the chloroform treatment softens the PMMA surface, producing a softened layer that the polisher removes simultaneously with the Au thin film.

James Madison University (JMU) faculty and K-12 teachers founded in 2011 the Shenandoah Valley Nanoscience Outreach Collaboration (SVNOC) effort. The goal of SNVOC is to help K-12 teachers incorporate nanoscience concepts into their classrooms. In this work we present how SVNOC participants use the Nanodays experimental kits to help students understand basic nanotechnology principles such as “How small is small?” Our preliminary results show that for PE the best experiments are the ones that are outside the operating schema of kids so they can stimulate further research. At the HS level, there is a consensus that students need more challenging mathematics that can be extracted from these experimental kits.

Due to their unique properties, nano-composite polyhedral oligomeric silsequioxane (POSS) copolymer films are attractive for various applications. Here we show that their natural hydrophobic character can become hydrophilic when the films are modified by a thin oxide layer, up to 8 nm thick, prepared using atomic layer deposition. A proper choice of the deposition temperature and thickness of the oxide layer are required to achieve this goal. Unlike other polymeric systems, a marked transition to a hydrophilic state is observed with oxide layers deposited at increasing temperatures up to the glass transition temperature (∼110 °C) of the POSS copolymer film. The hydrophilic state is monitored through the water contact angle of the POSS film. Infrared absorbance spectra indicate that, in hydrophilic samples, the integral of peaks corresponding to surface Al–O (hydrophilic) is significantly larger than that of peaks linked to hydrophobic species.

The adhesion of vapor deposited Au and Pt thin films onto poly(methyl methacrylate) (PMMA) substrates can be significantly enhanced by either spin‐casting or vapor‐exposure to hydrohalocarbon solvents prior to metal deposition. X‐ray photoelectron spectroscopy (XPS) and evolved gas analysis Fourier transform infrared spectroscopy detect residual halogenated solvent at the PMMA surface which chemically activates the surface. Density functional theory (DFT) calculations show that the solvent molecules form a Lewis acid‐base adduct with the ester oxygens in PMMA. DFT predicts that the deposited metal atom (M) inserts into the C–halogen (X) bond on either CHCl3 or CHBr3 to form a O–M–X interaction. This is consistent with M–X bonding observed in high resolution XPS. A model is proposed in which the bond energy of the C–X bond of the solvent must be weak enough so that it can be cleaved by the metal atom to form a M–X bond. A negative control of PMMA exposed to CHF3 is shown to have no effect on Au or Pt adhesion since the bond dissociation energy of the C–F bond is stronger than the C–Cl and C–Br bond energy compared to the metal halide bond energies.

There has been considerable interest in developing curricular programs and materials for teaching undergraduate courses in nanoscience in the United States and other developed countries in the past decade. Materials science and nanoscience research programs are growing in developing countries in South America, Africa and Asia. However, there still exists a significant disconnect between the research efforts in developing countries and undergraduate coursework. This report will focus on the teaching of an upper-division one semester lecture/laboratory course developed at James Madison University (JMU) called “The Science of the Small: An Introduction to the Nanoworld” taught in the School of Chemistry at the University of KwaZulu-Natal in Pietermaritzburg (UKZN-PMB), South Africa in 2009 through the Fulbright U.S. Scholar program. We report insights into the preparation needed to teach a cutting-edge laboratory course in South Africa. Also addressed will be some of the challenges of teaching an instrument-intensive laboratory course in a developing country, academic preparation of the typical native isiZulu-speaking UKZN undergraduate student compared to a typical U.S. student, and pre and post attitudes and content assessment of students who were enrolled in the course. Further discussed will be observations of post-apartheid science and math education in South Africa, and the beginning of a pilot program bringing South African undergraduate students to the U.S. to gain undergraduate research experience.

A variety of substrates have been used for fabrication of microchips for DNA extraction, PCR amplification, and DNA fragment separation, including the more conventional glass and silicon as well as alternative polymer-based materials. Polyester represents one such polymer, and the laser-printing of toner onto polyester films has been shown to be effective for generating polyester-toner (PeT) microfluidic devices with channel depths on the order of tens of micrometers. Here, we describe a novel and simple process that allows for the production of multilayer, high aspect-ratio PeT microdevices with substantially larger channel depths. This innovative process utilizes a CO2 laser to create the microchannel in polyester sheets containing a uniform layer of printed toner, and multilayer devices can easily be constructed by sandwiching the channel layer between uncoated cover sheets of polyester containing precut access holes. The process allows the fabrication of deep channels, with similar to 270 mu m, and we demonstrate the effectiveness of multilayer PeT microchips for dynamic solid phase extraction (dSPE) and PCR amplification. With the former, we found that (i) more than 65% of DNA from 0.6 mu L of blood was recovered, (ii) the resultant DNA was concentrated to greater than 3 ng/mu L., (which was better than other chip-based extraction methods), and (iii) the DNA recovered was compatible with downstream microchip-based PCR amplification. Illustrative of the compatibility of PeT microchips with the PCR process, the successful amplification of a 520 bp fragment of lambda-phage DNA in a conventional thermocycler is shown. The ability to handle the diverse chemistries associated with DNA purification and extraction is a testimony to the potential utility of PeT microchips beyond separations and presents a promising new disposable platform for genetic analysis that is low cost and easy to fabricate.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Alan K. Mo, Thomas C. DeVore, Brian H. Augustine, Vezekile P. Zungu, Laura L. Lee, Wm. Christopher Hughes; Improving the adhesion of Au thin films onto poly(methyl methacrylate) substrates using spun-cast organic solvents. J. Vac. Sci. Technol. A 1 May 2011; 29 (3): 030601. https://doi.org/10.1116/1.3562167 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAVS: Science & Technology of Materials Interfaces and ProcessingJournal of Vacuum Science & Technology A Search Advanced Search |Citation Search

We describe a model used for seeding nanoscience topics throughout the undergraduate chemistry curriculum at James Madison University (JMU). An overview of the evolutionary changes to the chemistry curriculum as a result of this program will be presented. Lecture topics in general, inorganic, organic, materials science and physical chemistry have been added or improved and laboratories for general, organic and physical, have been developed and implemented. A new general physical science course for nonscience majors and an upper-division majors lecture-laboratory course called, "Science of the Small: An Introduction to the Nanoworld" have been developed and will be broadly described. Nanoscience topics from the current scientific literature have been introduced into materials science, physical chemistry lab, and literature and seminar courses. We will further describe how a new series of vertically integrated laboratory experiments exploring the properties of supramolecular micelles are being used to introduce nanoscience into several different courses. In addition, we will discuss how this project, in particular the Science of the Small course, has helped to catalyze "top-down" thinking about seeding a range of interdisciplinary topics throughout the undergraduate chemistry curriculum. Finally, we address how this evolutionary approach can be used by non-experts to begin to seed nanoscience topics into the undergraduate chemistry curriculum.