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The 2017 Schoenborn Symposium Was Outstanding

The 2017 Schoenborn Graduate Research Symposium was an unqualified success!

The Symposium is divided into two sections. During the first section, senior-level PhD candidates make formal presentations about their research and the associated results. During the second section, mid-level PhD students make informal poster presentations about their research. Faculty judges select first-, second-, and third-place winners of the formal presentations and graduate student voters select the poster presentation winners.

The 2017  winners are:

Formal Presentations

First Place – Gilbert Castillo
[collapse title=”Functional Silicate Coatings for Polyesters” active=false]Background: The ability to modify the surface of PET in controllable fashion is an important asset to alter surface energy, improve chemical inertness, induce surface cross-linking, increase or decrease surface roughness and hardness, enhance surface lubricity and electrical conductivity, impart functional groups at the surface for specific interactions with other functional groups, and/or provide anti-fouling properties1. Addition of reactive functional groups to PET surfaces can serve as a means of generating anchoring points for grafting materials onto the PET surface, which can be utilized to further tune its surface characteristics. Surface modification of PET aims to take advantage of its inherent mechanical and optical properties, its malleability retain its low cost and ease of manufacturing.Results: We show that PET surfaces react with 3-aminopropyltriethoxysilane in aqueous solutions, and the reaction is much slower in other solvents (alcohols, tetrahydrofuran, and toluene). The procedure described here creates a uniform coverage of hydrolyzed APTES layer on PET surfaces as shown by thickness measurements and ToF-SIMS imaging, which has a lateral resolution of 60 nm. Water is an attractive solvent as it is non-flammable, non-toxic, and inexpensive, and thus makes this process suitable for scale-up. The formation of islands or cross-linked APTES aggregates was not observed either in AFM images or ToF-SIMS images. Furthermore, the described procedure should also be applicable to polyester fibers.Conclusions: The activation of PET with APTES followed by silicate films deposition serves as a platform to endow the surface with various functionalities by taking advantage of excess hydroxyl moieties present on the surface. These surface functionalities include (but are not limited to) (1) biocidal, anti-fouling, hydrophilic coatings for biomedical applications; (2) biocidal and anti-fouling finishes for filtering applications; and (3) hydrophobic surfaces for self-cleaning applications.References:

  1. Chan, C. M. Polymer Surface Modification and Characterization; Carl Hanser, GmbH & Co.: 1994 [/collapse]
Second Place – Jonathan M. Conway
[collapse title=”Building a better biofuels bug: Engineering plant biomass deconstruction and conversion in Caldicellulosiruptor bescii” active=false]Background: Caldicellulosiruptor species are anaerobic bacteria that are the most thermophilic (Topt = 70-75°C) microorganisms currently known to degrade lignocellulosic biomass, making them of interest as platform microorganisms for engineering the conversion of unpretreated plant biomass to bio-based fuels and chemicals. To date, the genomes of 12 Caldicellulosiruptor species have been fully sequenced and genomic, transcriptomic, proteomic, and phenotypic analysis has revealed genes of interest for evaluating and manipulating the native attachment, degradation, and conversion mechanisms of Caldicellulosiruptor species. Of particular interest are the large (~170-220 kDa), multi-domain enzymes produced by Caldicellulosiruptor species containing catalytic glycoside hydrolase (GH) and carbohydrate binding module (CBM) domains [1]. A subset of these enzymes also contains surface layer homology (SLH) domains, which associate these enzymes with the bacterial surface layer (S-layer).Results: Full-length and truncated recombinant versions of several of these enzymes have been produced in E. coli and C. bescii for characterization in vitro [2]. Crystal structures for GH and CBM domains from these enzymes have also been determined, providing structural information to complement the biochemical characterization. In addition to these in vitro analyses, genetic manipulations in C. bescii are being performed, using improved genetic tools [3], to test hypotheses about the role of these enzymes in vivo and to engineer improved plant biomass degradation in this non-model host. A strain of C. bescii expressing a xylanase from C. kronotskyensis showed improved ability to degrade xylan substrates and the enzyme was correctly localized on the cell surface within the S-layer [2]. To probe the role of enzymes involved in cellulose degradation, strategic subsets of enzymes in the glucan degradation locus, a locus of cellulases conserved in cellulolytic Caldicellulosiruptor species, were deleted from the genome. The ability of these strains to degrade crystalline cellulose and plant biomass was evaluated to elucidate the role of these enzymes in the degradation of varied substrates.Conclusions: These complementary in vitro and in vivo approaches are providing an improved fundamental understanding of the native mechanisms of plant biomass recruitment, degradation, and conversion in Caldicellulosiruptor species. Using the advancing genetic tools for manipulating C. bescii, we are leveraging this understanding to engineer strains with improved biomass degradation ability looking towards the production of bio-fuels and bio-chemicals from lignocellulosic feedstocks.References:

  1. Conway, J.M., J.V. Zurawski, L.L. Lee, S.E. Blumer-Schuette, R.M. Kelly. (2015) Lignocellulosic Biomass Degradation by the Extremely Thermophilic Genus Caldicellulosiruptor. In: Thermophilic Microorganisms. Fuli Li, editor. Caister Academic Press. pp 91-120.
  1. Conway, J.M., W.S. Pierce, J.H. Le, J.H. Wright, G.W. Harper, A.L. Tucker, J.V. Zurawski, L.L. Lee, S. E. Blumer-Schuette, R.M. Kelly. (2016) Multi-Domain, Surface Layer Associated Glycoside Hydrolases Contribute to Plant Polysaccharide Degradation by Caldicellulosiruptor J. Biol. Chem. 291, 6732-6747.
  1. Lipscomb, G.L., J. M. Conway, S.E. Blumer-Schuette, R.M. Kelly, and M.W.W. Adams. (2016) Highly Thermostable Kanamycin Resistance Marker Expands the Toolkit for Genetic Manipulation of Caldicellulosiruptor bescii. Appl. Environ. Microbiol. 82(14), 4421-4428. [/collapse]
Third Place – Russell W. Mailen
[collapse title=”Light Responsive, Shape Memory Polymer Sheets” active=”false”]Background: Shape memory polymers (SMPs) represent a class of active materials that can change shape in response to external stimuli such as heat, light, pH, solvents, and magnetic fields. Although SMPs have many applications, we are primarily interested in using the material as environmentally responsive actuators for self-folding origami structures. Thermally activated SMPs can change shape in response to heat, and are desirable due to their low cost and tailorable properties. Self-folding can be used to obtain three-dimensional (3D) structures from planar sheets for an array of applications, including medical stents, antennas, and engineered, origami applications, such as space telescopes.Previously, we developed a method to activate SMPs using light. [1] To do this, we pattern black ink onto pre-strained polystyrene sheets. When placed under an infrared (IR) light, the black ink absorbs light more efficiently than the unpatterned regions of the polymer sheet. This local light absorption results in localized heating beneath the ink, and produces a temperature gradient through the thickness of the sheet. The material shrinks locally wherever the activation temperature, Ta, is exceeded. Because there is a gradient in temperature, there is a gradient in shrinkage, and the material deforms out-of-plane.Results: We investigate the thermo-mechanical response of heat activated SMPs by extending a previously developed finite element model [2] to account for both external and internal heat sources. The SMP can heat due to external heat sources, such as light, or from internal viscous heating. Viscous heating affects significantly the response of SMP sheets by increasing the temperature during pre-strain which accelerates stress relaxation. This stress relaxation results in a slower shrinking rate when the SMP is reheated. Viscous heating also causes a significant increase in temperature during unconstrained recovery. Our model shows how the coupled thermo-mechanical loading conditions affect folding and unfolding of SMP sheets in response to localized heating in a ‘hinged’ region. We conduct a parametric study of sheet thickness, hinge width, degree of pre-strain, and hinge surface temperature, and we demonstrate methods for generating 3D, curved structures.Conclusions: We show the importance of accounting for both external and internal heat sources when predicting the shape of SMP sheets that respond to light. Furthermore, complex shapes can be obtained by carefully designing the placement and darkness of ink on the sheet. The results can be used to set guidelines for the design of functional, self-folding SMP structures.References:

  1. Ying Liu, Y., Boyles, J., Genzer & Michael D. Dickey. Self-folding of polymer sheets using local light absorption. Soft Matter 8, 1-6 (2012).
  1. Mailen, R.W., Liu, Y., Dickey, M.D., Zikry, M. & Genzer, J. Modelling of shape memory polymer sheets that self-fold in response to localized heating. Soft Matter 11, 7827-7834 (2015).[/collapse]

Poster Presentations

First Place – Ishan Joshipura [collapse title=”Reversible Actuation of Soft Liquid Metal Plugs in Microfluidic Systems Using Low Voltages” active=false]

Background: Integrating liquid metals with other low modulus materials, such as elastomers and gels, imparts high electrical conductivity into a composite without altering its mechanical properties. Combined, these materials form ‘softer than skin’ systems that are well-suited for forming conformal interfaces and ultra-compliant soft electronics. This work characterizes the behavior of a eutectic alloy of gallium and indium (75% Ga, 25% In, by weight, ‘EGaIn’) in response to electric fields. The metal remains a liquid at room temperature (M.P., 15.5 oC) and has low toxicity. These fluidic metals are injectable into microfluidic systems, fibers, and capillary networks. Once injected, the metal remains in its place because of the adhesive nature of its thin native oxide. Preventing the oxide adhesion within microchannels enables reversible actuation of EGaIn. Actuating liquid metals may be useful for soft actuators, reconfigurable optical displays, frequency tunable antennas, and other opto-fluidic technologies.

Results: This work studies methods to reversibly move droplets of EGaIn through microchannels using low voltages. Pre-wetting the channels with an aqueous solution prior to injecting the metal prevents oxide adhesion; the water forms an interfacial ‘slip-layer’ between the metal and channel wall. Thereafter, an applied electric field (~10-20 V/m) actuates the liquid metal by establishing a gradient of surface tension; this effect is known as continuous electrowetting (CEW). Although CEW has been utilized before with mercury, which is toxic, the presence of a Ga oxide complicates CEW behavior. This work compares the electro – hydrodynamic behavior of EGaIn with and without the presence of an oxide ‘skin’. Optical microscopy and electrochemical measurements characterize the movement of EGaIn droplets under a variety of conditions. Specifically, we elucidate the influence of the electrolyte (i.e., composition, pH, and viscosity) on the metal-electrolyte interface. In addition, thin film interference characterizes the thickness and dynamics of the interfacial slip-layer of water.

Conclusions: Evaporation of water may cause the slip-layer to disappear and impede CEW. Therefore, this work explores novel microfabrication strategies to design interfaces that prevent oxide adhesion. These interfaces form alternative slip-layers, which also renders microfluidic channels with self- healing and self-cleaning abilities. In addition, these interfaces may be useful for the transport of chemical or biological samples within three-dimensional microfluidic devices and vascular networks using low voltages. [/collapse]

Second Place – Sabina Islam [collapse title=”Structural Color: From Butterfly Wings to Polymer Films” active=false]

Background: Aromatic polyesters are one of the most important classes of polymers in textile and packaging industries due to their superior mechanical, optical, and processing properties. In order to comply with the low-VOC movement, such specialty polyesters were rendered water-dispersible by functionalizing the polymer backbone with ionic monomers. As a result of being partially soluble, these polyesters forms self-assembled nanoscale particles in water without the requirement of any additional stabilizer(s). These extremely small sized (~20 nm) nanoparticles are composed of hundreds of polymer molecules and offer various colloidal and morphological properties that are significantly different from the conventional emulsion polymerized latex particles. For instance, their nanometer dimensions can be very useful for developing nanocoatings with interesting optical properties.

Results: We fabricated nanofilms of brilliant colors using these polymer dispersions via facile convective deposition method. The microscale thickness of these nanofilms could be correlated to their macroscale optical properties via the constructive interference theory. Additionally, surface roughness modulation of these nanocoatings allowed us to obtain thin-film interference on both macro- and micro-level. Moreover, we observed coffee-ring effect as the addition of water droplets on such thin-films created multiple colorful ring-patterns where surfactants or electrolytes suppressed this effect.

Conclusions: Structural colors of purely physical origin are gaining a lot of interest in industries and academia due to numerous benefits over pigment-based colors, such as more vibrant color formation, resistance to photobleaching, and environment-friendly as no toxic chemical is required. This research is important in understanding the fundamental mechanism of film formation by these polymer nanoparticles. Moreover, the findings of our study open a new possibility and application of such environment-friendly waterborne dispersions in painting, photonic paper, and optical displays. [/collapse]

Third Place (tie) – Amber Hubbard [collapse title=”Curvature of Light Responsive, Shape Memory Polymers for the Production of Biologically Inspired, Functional Devices” active=false]

Background: Folding and bending are common phenomena found in nature, prominent in the formation of structures ranging from plants to proteins. By harnessing the potential of man-made materials, self-folding structures have applications in everything from biomedical engineering to transportation methods. Past research has focused on the ability to understand self-folding mechanisms of thermoplastics for use in robotic structures or simplistic shape formation [1-3]. Particular interest in self-bending materials has focused on the ability to control bimorph systems composed of hydrogels or elastomeric materials [4-5]. However, hydrogels and elastomers lack the strength needed for many practical applications. This work takes inspiration from nature to design thermoplastic structures that mimic natural systems through the generation and control of self-automated folds and global curvature. By increasing the complexity of possible designs, we can have a greater impact and generate final structures with a wider range of overall applications.

Results: We induce self-actuation into our materials by patterning pre-strained polystyrene films with ink from an inkjet printer. The polystyrene sheets are pre-strained to shrink by ~ 55% when heated above their activation temperature (Ta ~ Tg) which is ~ 103°C. By patterning inked regions along the surface of the material localized heating, and therefore shrinkage, is achieved via strain gradients through the thickness of the material [1]. The design of these inked regions (i.e., ink darkness and distribution) determines the direction of folding, onset actuation time, and final structure. These results are compared with finite element modeling as a predictive tool [6].

Conclusions: An indirect and direct mechanism of curvature were identified and systematically studied with our self-actuated polystyrene material. This global curvature control is useful for the production of positive and negative Gaussian curvature from planar polymer sheets. The degree of curvature is directly related to the ink distribution and darkness of each sample as well as the aspect ratio and geometry of the starting substrates. Experimental and computational results were quantitatively and qualitatively compared with excellent agreement for the production of biologically-inspired gripping devices with the ability to hold ~ 925x their own weight.


  1. Liu, Y., Boyles, J., Genzer, J., & Dickey, M. Self-folding of polymer sheets using local light absorption. Soft Matter. 8, 1-6 (2012).
  2. Felton, S., al., Self-folding with shape memory composites. Soft Matter 9, 7688-7694 (2013).
  3. Liu, Y., Mailen, R., Zhu, Y., Dickey, M., & Genzer, J. Simple geometric model to describe self-folding of polymer sheets. Rev. E 89, 1-8 (2014).
  4. Eugonov, A., Korvink, J., Luchnikov, V. Polydimethylsiloxane bilayer films with an embedded spontaneoud curvature. Soft Matter 12, 45-52 (2016).
  5. Abdullah, A., Braun, P., Hsia, K. Programmable shape transformation of elastic spherical domes. Soft Matter 12, 6184-6195 (2016).
  6. Mailen, R., Liu, Y., Dickey, M., Zikry, M., Genzer, J. Modelling of shape memory polymer sheets that self-fold in response to localized heating. Soft Matter 11, 7827-7834 (2015). [/collapse]
Third Place (tie) Dishit Parekh [collapse title=”LM3D: Liquid Metal-based 3D Printing of Flexible & Wearable Electronic Devices” active=false]

Background: 3D printing is the process of joining materials to build objects from a computer-aided model (CAD) data, usually layer-upon-layer. Polymers are the most common materials to be printed today due to the simplicity of extruding them in molten form that quickly cools and hence solidifies. Although there is a great demand for printing conductive inks for electronics [1], current methods for 3D printing metals tend to be prohibitively expensive, and use energy-intensive lasers at sintering temperatures in excess of 800°C. Secondly, they need vacuum-like pressures to avoid oxidation while handling metal nanoparticles, leading to porosity in finished parts, low resolution and poor electrical conductivity, apart from having slow printing speeds. Finally, the operating procedures are impossible to integrate them with various polymeric, organic, soft and biological materials. Here, we present an alternate but simple approach that utilizes low melting point gallium-based alloys as complements to existing materials for 3D printing electronics allowing co-printing of these metals with polymers at room temperature.

Results: We have utilized these metals to build mechanically stable structures due to the formation of a thin oxide skin on the surface [2] despite having high surface tension (~10x water). The oxide skin is passivating, forms spontaneously in presence of air or dissolved oxygen and allows us to direct-write planar as well as free-standing, out-of-plane conductive microstructures down to a resolution of ~10 microns [3], on-demand using a shear-driven flow occurring at relatively low pressures (~10s of kPa). We exhibit the patterning of 3D multilayered microchannels with vasculature using these printed liquid metals acting as a sacrificial template at room-temperature [4], that can be employed in numerous lab-on-a-chip devices. We also demonstrate rapid prototyping of functional electronics such as flexible and stretchable antennas for radio-frequency defense communications, as well as consumer-based electronic devices like inductive power coils for wireless charging of smartphones, and wearable thermoelectric generators (TEGs) for energy-harvesting applications.

Conclusions: In summary, we show that a shear-driven flow dispensing approach for printing liquid metals can fabricate 2D & 3D microarchitectures. This mechanism validates that skin forming liquids can be molded into several shapes earlier prohibited by the weakening effects of gravity and surface tension, in order to print soft electronic devices at room temperature.


  1. Parekh, Dishit P., Denis Cormier, and Michael D. Dickey (2015). Multifunctional Printing: Incorporating Electronics into 3D Parts Made by Additive Manufacturing. Additive Manufacturing, CRC Press, 8: 215-258.
  1. Michael D. Dickey (2014). Emerging Applications of Liquid Metals Featuring Surface Oxides. ACS Appl. Mater. Interfaces., 6: 18369-18379.
  1. Trlica, C., Dishit P. Parekh, Laza Panich, Collin Ladd, and Michael D. Dickey (2014). 3-D Printing of Liquid Metals for Stretchable and Flexible Conductors. Proceedings of SPIE, 9083: 1-10.
  1. Parekh, Dishit P., Collin Ladd, Laza Panich, Khalil Moussa, and Michael D. Dickey (2016). 3D Printing of Liquid Metals as Fugitive Inks for Fabrication of 3D Microfluidic Channels. Chip, 16: 1812-1820. [/collapse]

View the complete program here

 Alum Dr. Elizabeth Wilder (Ph.D., 2003)  delivered the Keynote talk, “Beyond Technical Mastery:  The leadership skills that can make you stand out.”  Dr. Widener is a Senior Scientist at Procter & Gamble.

The Vivian T. Stannett Fellow Award is also presented at the Symposium. It’s named in memory of Professor Vivian T. Stannett, a CBE faculty member who was an internationally renowned polymer scientist, research leader, and member of the National Academy of Engineering. The Award recognizes research excellence, initiative, focus and tenacity during the early careers of Ph.D. candidates in the department.  The 2017 award winners are Ryan Leenay, Fellow, and Ishan Joshipura, the second-place awardee.

The Fall 2017 Praxair Exceptional Teaching Assistant Award was presented to Kaihang Shi.  The Award recognizes instructional effectiveness and management skills of Ph.D. candidates who serve as exemplary teaching assistants in CHE courses. The Award recipient goes above and beyond the call of duty and provides students with tireless and selfless attention to high-quality instruction and professionalism.

Congratulations to the Schoenborn competition, Stannett and Praxair award winners and their advisers. Well done to all!

Be sure to mark your calendar for next year’s Symposium on January 22, 2018.