Office: BSF 312
Phone: (813) 974-3397
B.A., Mercyhurst College, 1971
M.S., Duquesne University, 1973
Ph.D., University of Rochester, 1983
Our research philosophy centers on the premise that applied research is most effective when it is basic in nature. In past years scientists often distinguished between basic and applied research. A more current line of thinking stresses the point that scientists are accountable to society to interface with industry in an effort to focus their basic understanding of scientific principles on the pertinent needs of society.
We have several exciting areas of research in our laboratories, including: high performance polymer composites with increased resistance to different types of radiation, optically transparent polymer/carbon nanotube composites with enhanced mechanical properties, polymer composites with high thermal conductivity, polymer nanocomposites that exhibit magnetic properties and new biocompatible composites based on hydrophilic polymers.
Our group has made important advances in carbon nanotube composite research. The goal of this research is to use carbon nanotubes as radiation sinks, dissipating energy and decreasing the frequency of radiolysis events. Most recently, progress has been made in solubilizing carbon nanotubes in polymer matrices. Optically transparent polymer composites with increased radiation resistance have been designed and tested and analyzed. This research resulted in two patent applications:
Harmon, J. P., Clayton, L., and Muisener, P., USF Invention Disclosure, "Transparent Polymer Nanotube Composites, "USF Ref No: 01B100, December 2001. Patent pending.
Harmon, J. P., Muisener, P., Clayton, L., and D'Angelo, J., USF Invention Disclosure, "Ionizing Radiation Resistant Carbon Nanotube/Polymer Composites", USF Ref. No. 01B090, December, 2001. Patent pending.
Another area of research in our group focuses on interaction of polymeric materials and highly energetic heavy atoms that are known to be part of Galactic Cosmic Radiation (GCR). A biological effectiveness (amount of damage) of the heavy ions consists of two major parts: a) energy transferred by a heavy particle along its trajectory, b) secondary radiation effects due to the nuclear interactions of incoming particles with shield material. Shield materials composed of atoms with small atomic mass (small number of inner shell electrons) have lower possibility of induced X-ray radiation as well as fewer neutrons to release during the nuclear interactions. Polymers consisting of only small atomic weight atoms (carbon, hydrogen) are considered to be promising materials for the production of GCR shields. Our group is in the process of developing new polymer nanocomposites that will show an enhanced resistance to GCR.
A new area of research is concerned with formulation, modification and characterization of biocompatible coatings. Certain hydrogels, due to their high biocompatibility, have been used in biomedical field as contact lens materials, bioadhesives, artificial tissue and implantable devices. The group is now engaged in synthesis and characterization of novel block-copolymer based hydrogel systems.
An important area of research in our group deals with optical fiber materials. This includes developing fiber core and cladding materials with controlled refractive indexes. One project focuses on designing polymeric core materials that are transparent in the near IR region of the electromagnetic spectrum. Another project involves the design in transparent, low refractive index cladding materials. In addition to stringent optical and mechanical criterion, the effect of ionizing radiation on optical and mechanical properties of these materials is also characterized. This work is applicable to space environments and to particle accelerators where scintillating optical fibers are used. Research involves collaborations with Optical Polymer Research Inc. and Honeywell Space Systems Group.
We have developed expertise in structure-property relations of dendrimers. Dendritic structures currently dominate the field of macromolecular chemistry in hopes that they will meet the need of the 21st century. Applications are found in drug therapy, polymer rheology modification and in nonlinear optical devices. Surprisingly, very little work has been done on characterizing these molecules by dielectric analysis. Our group has performed one of the first known dielectric analyses on neat, dendrimer molecules. These molecules exhibit relaxation phenomenon similar to those of linear macromolecules, exhibiting WLF behavior for the glass transition region and Arrhenius behavior for secondary relaxations. This is an area of expanding interest for our group.
View our currently funded projects here.
Synthetic Polymer/Matrix Crystallization
Inductively Based Fluidic (IBF) Sample Preparation for MALDI
Matrix-assisted laser desorption/ionization time of flight mass
spectrometry (MALDI-TOF-MS) is a powerful tool for the
characterization of biomarkers. Extensive, much needed research
is being devoted to improving the reproducibility and sensitivity
of MALDI signals by optimizing sample preparation techniques. We
are one of two universities worldwide to obtain an experimental
sample deposition device based inductively based fluidics (IBF)
that has the potential of greatly increasing signal to noise ratios
and will, hopefully, lead to the standardization of quantitative
MALDI techniques. IBF employs an electric field to kinetically
energize, direct and transport liquids to targets in a highly
parallel manner. It is well known that a plethora of sample
preparation problems currently hinder researchers. There is a lack
of fundamental understanding on how to formulate and deposit MALDI
targets to quantitatively interpret the observed mass spectrum.
The work that we are currently conducting shows that for the same
spot size, the signal to noise ratio for IBF samples is enhanced as
compared to the dry droplet method samples. This is prompting us to
focus more on sample morphology and crystallinity. We are interested
in how the electric field influences uniformity. We are also interested
in how spot sizes effect the signal to noise ratio. It is well known that
methods that concentrate sample spots on targets improve detection. The
IBF unit deposits denser sample with smaller radii than those obtained when
the same volume is deposited via the dry drop method. The nL samples are
enriched. In addition, the delivery is so precise that several depositions
can be made atop one another in layers, affording the opportunity for greater
MALDI samples consist of analytes mixed with a matrix and ion source in a solvent
which are deposited on the MALDI target. The matrix is, in reality, a laser dye.
That is, the spotted target is pulsed via a laser that emits light that is
absorbed by the matrix dye. The matrix is volatilized and pick up the analyte with
it. The analyte is ionized in the process and travels into the mass spectrometer for
analysis. This is a soft ionization technique; the analyte is not fragmented and the
mass can be determined. A vast number of compounds have been tested for use as MALDI
matrices using solvent formulations containing analytes and layering analytes on top
of matrix surfaces. We have selected well studied, high performance, formulations for
this research. Yet, using current deposition techniques, these solid matrices
crystallize during solvent desorption and produce regions of varying analyte
concentrations. For example, when the solutions are deposited by the dry drop method
via a micropipettor, non-uniform sample are produced. When the laser hits the MALDI
target the analyte concentration varies with position. When multiple analytes are used
it is impossible to quantify the concentrations. Matrix non-uniformity has plagued MALDI
operators since the onset of the instrumentation.
We have found that IBF depositions yield samples with distinctively different morphologies.
The series of movies and poster which are linked below illustrate the difference between
sample prepared by IBF and the micropipette. Notice the morphology development versus time
as the samples dry.
The MALDI recipe consists of 5.0 mg/ml Poly (methyl methacrylate) (Mn=10,600 Da)/ 40.0 mg/ml
2,5-dihydroxy benzoic acid/ 5 mg/ml NaTFA/ THF solvent. The components were mixed in a 1:10:1 ratio.
The IBF device was custom designed for us by Nanoliter LLC in Henderson, NV.
- MALDI-TOF-MS Sample Preparation for Synthetic Polymers via Nanoliter Induction Based Fluidic
Link to Poster (PDF) or
- Synthetic Polymer Crystallization Morphology Study for the preparation of samples for MALDI
Video File (Windows Media)
Garrett Craft, Kenneth Kull
- "Synthesis and Performance of Novel Hydrogels Coatings for Implantable Glucose Sensors", Chunyan Wang, Bazhang Yu, Bernard Knudsen, Julie Harmon, Francis Moussy, and Yvvone Moussy, Biomacromolecules, 9(2), 561, (2008).
- "Use of Hydrogel Coating to Improve the Performance of Implantable Glucose Sensors", B. Yu, C. Wang, Y. M. Ju, L. West, Julie Harmon, Y. Moussy, and F. Moussy, In Press, 2007.
- "Microscale Freeform Integration by Directed Self Assembly (review)", Nathan Crane, Mike Nellis, George Nolas, and Julie Harmon, submitted to Proceedings for Solid Freeform Fabrication Symposium, Austin, Texas, August (2007).
- "DC Conductivity and Interfacial Polarization in PMMA/Nanotube and PMMA/Soot Composites", LaNetra M. Clayton, Bernard Knudsen, Martin Cinke, M. Meyyappan, and Julie P. Harmon, Journal of Nanoscience and Nanotechnology, 7(10), 3572, (2007).
- "Dielectric Properties of PMMA/Soot Nanocomposites", LaNetra Clayton, Martin Cinke, M. Meyyappan and J. P. Harmon, Journal of Nanoscience and Nanotechnology, 7(7), 2494-2499, (2007).
- "Dispersion of Single-walled Carbon Nanotubes in a Non-polar Polymer, Poly(4-methyl-1-pentene)", LaNetra M. Clayton, Timofey G. Gerasimov, Martin Cinke, M. Meyyappan, and J. P. Harmon, Journal of Nanoscience and Nanotechnology, 6(8), 2520, (2006).
- "Dielectric Analyses of a Series of Poly(2-Hydroxyethy Methacrylate-co-2,3-Dihydroxypropyl Methacrylate) Copolymers", K. Mohomed, F. Moussy, and J. P. Harmon, Polymer, 47, 3856, (2006).
- "A Broad Spectrum Analysis of the Dielectric Properties of Poly(2-Hydroxyethyl Methacrylate", K. Mohomed, T. G. Gerasimov, F. Moussy, and J. P. Harmon, Polymer, 46, 3847, (2005).
- "Thermal Analysis of Novel Underfill Materials with Optimum Processing Characteristics", Y. Liu, Yi-Feng Wang, T. G. Gerasimov, K. H. Heffner and J. P. Harmon, Journal of Applied Polymer Science, 98 (3), 1300, (2005).
- "Persistent Interactions Between Hydroxylated Nanoballs and Atactic Poly(hydroxyethyl methacrylate) (PHEMA)", Kadine Mohomed, Heba Abourahma, Michael J. Zaworotko and Julie P. Harmon, Chemical Communications, 98 (3), 1300, (2005).
- "The Effect of Host Nanoparticle Interactions on Polymer Relaxations", K. Mohomed, T. Gerasimov, H. Abourahma, M. Zaworotko and J. P. Harmon, Materials Science and Engineering A, Vol. 409/1-2, 227, (2005).
- "Modifying Electronic Character of Single-Walled Carbon Nanotubes through Anisotropic Polymer Interaction: A Raman Study", Bin Chen, Martin Cinke, Meyya Meyyappan, Z. Chi, J. Harmon, P. Muisener, L. Clayton, and J. D'Angelo, Advanced Functional Materials, 15(7), 1183, (2005).
- "Transparent PMMA/SWNT Composites with Increased Dielectric Constants", L Clayton, T. Gerasimov, M. Meyyappan and J. P. Harmon, Advanced Functional Materials, Vol. 15, No. 1, 101, (2005).
- "In Situ Synthesis and Performance of Titanium Oxide/Poly(Methyl methacrylate) Nanocomposites",Uttam C. Bandugula, L.M. Clayton, J.P. Harmon, and Ashok Kumar, Journal of Nanoscience and Nanotechnology, 5(5) 814, (2005).
- "Characterizations of Enriched Metallic Single-walled Carbon Nanotubes in Polymer Composite", B. Chen, J.Yijian, M. Cinke, D. Au, J. P. Harmon, P. Muisener and L. Clayton, Accepted for publication in MRS Proceedings, Volume 856E, Multicomponent Polymer Systems-Phase Behavior, Dynamics and Applications, Editors: K.I. Winey, M. Dadmun, C. Leibig, R. Oliver, 2004.
- "In-Situ Synthesis and Magnetic Properties of Polystyrene/Polypyrrole Nanocomposite Materials With Uniformly Dispersed Nanoparticles", H. Srikanth, P. Poddar, J. L. Wilson, K. Mohomed and J. P. Harmon, Submitted the MRS Meeting Proceedings, Paper 1699, 49864, Symposium L, Fall 2003.
- "Transparent PMMA/SWNT Composites with Increased Dielectric Constants", L Clayton, T. Gerasimov, M. Meyyappan and J. P. Harmon, Submitted to Advanced Functional Materials October, 2003
- "Ionizing Radiation Effects on PMMA/SOOT Nanocomposites", L. Clayton, T. Gerasimov and J. P. Harmon, Submitte to Polymers for Advanced Technologies Manuscript, November, 2003.
- "Modeling and Simulation of Aggregation Processes in Colloidal Systems," Gita T. Iranipour, Luis H. Garcia-Rubio, and Julianne P. Harmon, Submitted to J. of Dispersion and tech, October, 2003.
- "Synthesis and Magnetic Properties of Polymer Nanocomposites with Embedded Iron Nanoparticles", J. L. Wilson, P. Poddar, N. A. Frey, H. Srikanth, K. Mohomed, J. P. Harmon, S. Kotha, & J. Wachsmuth, Accepted for publication in J. Apply. Phys, November 2003.
- "Transparent Polymer-Nanotube Composites Produced Via Solar Radiation, Ionizing Radiation and Heat", L. M. Clayton, J. P. Harmon, M. Meyyappan, M. Cinke, A. Cassell, A. Kumar and A. K. Sikder, Materials Research Society Proceedings, Vol. 697, P9.7 (2002).
- "The Evolution of Surface Morphology of Hydroxyl Ethyl Methacrylate Copolymer Exposed to Gamma Radiation", K-F. Chou, S. Lee, and J.P.Harmon, Submitted for publication in Macromolecules, 36 (15), 5683 (2003).
- Harmon, Julie P.; Johns, Ken; Thomas, Richard R.; Galli, Giancarl; Owen, Michael J.; Smith, Dennis W.; Kharitonov, Alexandre P.; Tressaud, Alain; Goodwin, Andy; Weinert, Raymond; Poggio, Tiziana; Masuda, Sho; Lin, Shiow-Ching; Dasgupta, Dip; Ameduri, Druno; Clarson, Stephen; Wood, Kurt; Zhang, Yunxiang; Montefusco, Francesca; Miller, William A.; Dietz, Timothy. Fluorine in Coatings V. (Conference Papers held in Orlando, Florida 21-22 January 2003.).
- "A MALDI, TGA, TG/MS and DEA Study of the Irradiation Effects on PMMA", S. R.Tatro, G. R. Baker, K. Bisht and J. p. Harmon, Polymer, 44, 167 (2003).
- "2,3-Dihydroxypropyl Methacrylate and 2-Hydroxyethyl Methacrylate Hydrogels: Gel Structure and Transport Properties" G. Gates and J. P. Harmon, Polymer 44, 215 (2003).
- "Intra and Intermolecular Relaxations 2,3-Dihydroxypropyl Methacrylate and 2-Hydroxyethyl Methacrylate Hydrogels" G. Gates and J. P. Harmon, Polymer 44, 207 (2003).
- "Thermally-Induced Crack Healing in Poly(Methyl Methacrylate)"., Shen JS, Harmon JP, Lee S, Journal of Materials Research, 17, No. 6, 1335 (2002).
- "Effects of Gamma Radiation on Poly(methyl methacrylate)/ Single-wall Nanotube Composites," O'Rourke Muisener, P., Clayton, L., D'Angelo, J., and Harmon, J. P, Journal of Materials Research, 17, No. 10, 2507 (2002).
- "Ionizing Radiation Effects on Interfaces in Carbon Nanotube-Polymer Composites," Julie P., Muisener, P. A. O., Clayton, L., D'Angelo, J., Sikder, A. K., Kumar, A., Meyyappan, M., and Cassell, A. M., Materials Research Society Proceedings, Vol. 697, P9.7 (2002).
- "Matrix Assisted Laser Desorption/Ionization (MALDI) Mass Spectrometry: Determining Mark-Houwink Sakaurada Parameters and Analyzing The Breadth of Polymer Molecular Weight Distributions", S. Tatro, G. Baker, R. Fleming and J. Harmon, Polymer,43 (8) 2329 (2002).
- "Evaluation of Mechanical and Triboloical Behavior, and Surface Characteristics of CMP Pads", A. K. Skidder, I. M. Irfan, A. Kumar, S. Ostapenko, M. Calves, J. P. Harmon and J. M. Anthony, Materials Research Society Symposium Proceedings, Vol. 671, M1.81 (2001).
- "Viscoelastic Properties and Phase behavior of 12-tert-Butyl Ester Dendrimer/Poly (Methyl Methacrylate) Blends", S. Emren, Y. Liu, G. Newkome and J. P. Harmon, Journal of Polymer Science Part B: Polymer Physics, Vol. 39, 1381 (2001).
- "Water Structure in Hydroxyethyl-Co-Glycerol Methacrylate Materials," G. Gates, J. P. Harmon, J. Ors and P. Benz, ANTEC, Proceedings of the Annual Technical Conference and Exhibition, Vol. XLVII, Dallas, Texas, May 6-11, 2001, 1891.
- "Creep and Stress Relaxation in Methacrylate Polymers; Two Mechanisms of Relaxation Behavior Across the Glass Transition Region," P. Bertolucci and J. P. Harmon, Polymer Engineering and Science, Vol. 41, No. 5, 873 (2001).
- "Polymers for Optical Fibers and Waveguides," J. P. Harmon. Advances in Optical Fibers and Waveguides, Eds. J. P. Harmon and G. Noren, American Chemical Society Symposium Series 795 ( 2001) 1.
- "Miscibility Investigation of Fluorocarbon Copolymer and Methacrylate Copolymer Blends", M. Calves and J. P. Harmon, . Advances in Optical Fibers and Waveguides, Eds. J. P. Harmon and G. Noren, American Chemical Society Symposium Series 795 ( 2001) 91.
- "Polymer Scintillators - Continuous Versus Intermittent Gamma Irradiation Effects", E. Biagtan, E. Goldberg, R. Stephens, E. Valeroso, M. Calves and J. P. Harmon, .Advances in Optical Fibers and Waveguides, Eds. J. P. Harmon and G. Noren, American Chemical Society Symposium Series 795 ( 2001) 221.
- "Enzyme Catalyzed Ring-Opening Copolymerization of 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) with Trimethylene Carbonate (TMC): Synthesis and Characterization," T. F. Alzemi, J. P. Harmon and K. S. Bisht, Biomacromolecules, Vol. 1, 493 (2000).