Current Projects

Metal nanoparticles: near and far field manipulation of light

A research tool for nanoscale physics

Nanoscale metal objects possess a localized surface plasmon resonance (LSPR) -- that is, resonant optical light can excite a coherent oscillation of conduction electrons ("plasmon"). This oscillation enhances the local electric field around the nanostructure, and can also influence the properties of other objects located close to the metal structure.

  • On fairly short time scales, the plasmon damps out and thereby releases the energy as heat within the nanostructure which through thermal transport processes, propagates outwards from the nanoscale metal object into the surrounding environment; this overall "light-to-heat" conversion process is referred to as a photothermal effect. Our research efforts have recently focused on utilizing such "nano-heater" objects using sample systems when they are intentionally embedded within solid materials and illuminated with appropriate light to excite the LSPR, in order to demonstrate thermal processing outcomes which are unrealizeable by traditional heating means which is typically 1) from the outside of an object to the inside, and 2) not originating from nano-sized structures. We have developed unique (mainly optical-based) research tools to subsequently measure the spatial temperature distribution at nanoscale length scales which arise under such photothermal heating. These efforts mainly employ the unique and robust absorptive properties of the metal nanoparticles themselves, as well as independent signals generated from molecular fluorophores, randomly-distributive within the material matrix.

  • Future work will focus on fundamental light-matter interactions by exploring the influence of metal nanoparticles on the emission properties of quasi-resonant light-emitters intenionally placed extremely near the metal nanoparticle while their LSPR is also excited. In this regime, the extremely strong local electric field can dramatically modify the emissive and absorptive properties of the light-emitters. We will separately experiment with both atom-nanoparticle as well as molecule-nanoparticle interactions, in two related, but different realized systems.

Most recent papers:
  • Ju Dong, G. Firestone, J. R. Bochinski, L. I. Clarke, and R. E. Gorga,
    "In-situ curing of liquid epoxy via gold-nanoparticle mediated photothermal heating,"
    Nanotechnology 28, 065601 (2017).
    (journal) [paper] [DOI: 10.1088/1361-6528/aa521b]

  • V. Viswanath, S. Maity, J. R. Bochinski, L. I. Clarke, and R. E. Gorga,
    "Enhanced crystallinity of polymer nanofibers without loss of nanofibrous morphology via heterogeneous photothermal annealing,"
    Macromolecules 49, 9484 (2016).
    (journal) [paper] [DOI: 10.1021/acs.macromol.6b01655]

  • S. Maity, Wei-Chen Wu, C. Xu, J. B. Tracy, K. Gundogdu, J. R. Bochinski, and L. I. Clarke,
    "Spatial Temperature Mapping within Polymer Nanocomposites Undergoing Ultrafast Photothermal Heating via Gold Nanorods,"
    Nanoscale 6, 15236 (2014).
    (journal) [paper] [DOI: 10.1039/C4NR05179C]

  • D. B. Abbott, S. Maity, M. T. Burkey, R. E. Gorga, J. R. Bochinski, and L. I. Clarke,
    "Blending with Non-Responsive Polymers to Incorporate Nanoparticles into Shape Memory Materials and Enable Photothermal Heating: The Effects of Heterogeneous Temperature Distribution,"
    Macromolecular Chemistry and Physics 215, 2345 (2014).
    (journal) [paper] [DOI: 10.1002/macp.201400386v]

  • (See Publications for a more complete list of papers.)

    Edge electrospinning

    Creating, controlling, and scaling up production of nanofibrous structures

    Traditional solution-phase needle electrospinning is a remarkably simple approach to create nanometer-sized homogeneous pure or composite polymeric fibers; a single conducting needle held at high electric potential controllably expels (via a mechanical pump) a polymer solution, which may contain chemically-compatible additives to enhance the electrical, optical, or mechanical properties of the ultimately-formed composite. The solution subsequently undergoes a linear jetting, before choatically whipping (and physically eliminating the solvent from the material) and finally depositing a dry fiber onto a grounded collector plate. While extremely successful for facile, low mass research laboratory requirements, the approach is labor-intensive and the fabrication rate is slow; incompatible for industrial-level mass production requirements.

    • By understanding the underlying physical principles that control the electrospinning process, alternative geometries can be realized which have improved production rates as well as other enhanced capabilities.

    • In turn, these alternative configurations can potentially enable more optimal applications of electrospinning using polymer melts (instead of necessitating solvating the material), with dramatic improvements in through-put (i.e., an increased mass-production rate) while retaining the desirable characteristics of high surface-to-volume ratio and porosity of the fabricated nano-materials.

    Most recent papers:
  • N. M. Thoppey, R. E. Gorga, L. I. Clarke, and J. R. Bochinski,
    "Control of the electric field - polymer solution interaction by utilizing ultra-conductive fluids,"
    Polymer 55, 6390 (2014).
    (journal) [paper] [DOI: 10.1016/j.polymer.2014.10.007]

  • Q.-Q. Wang, C. K. Curtis, N. M. Thoppey, J. R. Bochinski, R. E. Gorga, and L. I. Clarke,
    "Unconfined, melt edge electrospinning from multiple, spontaneous, self-organized polymer jets,"
    Materials Research Express 1, 045304 (2014).
    (journal) [paper] [DOI: 10.1088/2053-1591/1/4/045304]

  • (See Publications for a more complete list of papers.)