Education

Research Description

Dr. Spontak's research interests include effects of homo/copolymer blending, molecular architecture, monomer sequencing, and solvation on the phase behavior of microstructural polymer systems.

Publications

Communication: Molecular-level description of constrained chain topologies in multiblock copolymer gel networks

Tuhin, M. O., Woloszczuk, S., Mineart, K. P., Pasquinelli, M. A., Sadler, J. D., Smith, S. D., Banaszak, M., & Spontak, R. J. (2018), Journal of Chemical Physics, 148(23).

Ordering and grain growth in charged block copolymer bulk films: A comparison of solvent-related processes

Ryan, J. J., Mineart, K. P., Lee, B., & Spontak, R. J. (2018), Advanced Materials Interfaces, 5(8).

Nafion/IL hybrid membranes with tuned nanostructure for enhanced CO2 separation: Effects of ionic liquid and water vapor

Dai, Z. D., Ansaloni, L., Ryan, J. J., Spontak, R. J., & Deng, L. Y. (2018), Green Chemistry, 20(6), 1391-1404.

Swelling and free-volume characteristics of TEMPO-oxidized cellulose nanofibril films

Torstensen, J. O., Liu, M., Jin, S. A., Deng, L. Y., Hawari, A. I., Syverud, K., Spontak, R. J., & Gregersen, O. W. (2018), Biomacromolecules, 19(3), 1016-1025.

Quasi-solid-state dye-sensitized solar cells containing a charged thermoplastic elastomeric gel electrolyte and hydrophilic/phobic photosensitizers

Al-Mohsin, H. A., Mineart, K. P., Armstrong, D. P., El-Shafei, A., & Spontak, R. J. (2018), Solar RRL, 2(3).

Effect of systematic hydrogenation on the phase behavior and nanostructural dimensions of block copolymers

Ashraf, A. R., Ryan, J. J., Satkowski, M. M., Smith, S. D., & Spontak, R. J. (2018), ACS Applied Materials & Interfaces, 10(4), 3186-3190.

Complex phase behavior and network characteristics of midblock-solvated triblock copolymers as physically cross-linked soft materials

Woloszczuk, S., Tuhin, M. O., Gade, S. R., Pasquinelli, M. A., Banaszak, M., & Spontak, R. J. (2017), ACS Applied Materials & Interfaces, 9(46), 39940-39944.

Nanoscale considerations responsible for diverse macroscopic phase behavior in monosubstituted isobutyl-POSS/poly(ethylene oxide) blends

Caydamli, Y., Yildirim, E., Shen, J. L., Fang, X. M., Pasquinelli, M. A., Spontak, R. J., & Tonelli, A. E. (2017), Soft Matter, 13(46), 8672-8677.

Molecular dynamics study of polystyrene-b-poly(ethylene oxide) asymmetric diblock copolymer systems

Dobies, M., Makrocka-Rydzyk, M., Jenczykt, J., Jarek, M., Spontak, R. J., & Jurga, S. (2017), Langmuir, 33(36), 8856-8868.

Bicomponent block copolymers derived from one or more random copolymers as an alternative route to controllable phase behavior

Ashraf, A. R., Ryan, J. J., Satkowski, M. M., Lee, B., Smith, S. D., & Spontak, R. J. (2017), Macromolecular Rapid Communications, 38(17).

View all publications via NC State Libraries

Grants

EMN-17-F-03 Novel Emulsion-based PDLC Systems with New and Enhanced Functionalities

Eastman Chemical Company(3/01/18 - 10/02/18)

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EMN-17-F-03 Novel Emulsion-based PDLC Systems with New and Enhanced Functionalities

Sponsor: Eastman Chemical Company

Start Date: 3/01/18

End Date: 10/02/18

Abstract

Polymer dispersed liquid crystal (PDLC) materials have been extensively studied for over two decades. However, the current PDLCs suffer from several faults including low viewing angle, switching speeds and voltage, desired transparency and haze, making them untenable for use by Eastman in their smart window applications. We propose creation of three 'emulsion-based' LC platforms to produce PDLCs with fast switching speed and desirable optical properties. These nontraditional, innovative approaches include (1) creation of isotropic LC dispersions/emulsions in a UV curable (or other crosslinkable) polymer matrix via shear driven mixing . This idea, which emanates from prior work in one of our laboratory (Figure 1), will allow us to refractive match various LCs with polymers; and unlike conventional systems will be isotropic in its 'off' configuration (2) development of pickering emulsions of LC domains that will be dispersed throughout the polymer matrix. In this case the LCs are actual emulsion droplets stabilized by colloidal particles acting as surfactant, and ensuring enhanced stability; and (3) creation of oligomer/LC domains within a polymer matrix. One can envision these oligomer/LC domains as emulsions droplets dispersed within the polymer. While initially isotropic, any applied field will create anisotropy by creating phase separation between the LC and oligomer. The strength of our work lies in (i) the suggested platform that will alleviate current problems with PDLCS (e.g., faster response, desired optical properties) to create new functionalities, (ii) our multi-prong approach to ensure success, and (iii) the complementary expertise of the PIs (Velev-LC emulsion creation and optoelectronics; Spontak-LC characterization, morphology and phase behavior; Khan-LC/polymer rheology, crosslinking and mechanical properties) to offer a synergistic team.

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EMN-15-F-S-01 Molecular Modeling of Amines for Gas Sweetening

Eastman Chemical Company(4/01/16 - 12/31/17)

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EMN-15-F-S-01 Molecular Modeling of Amines for Gas Sweetening

Sponsor: Eastman Chemical Company

Start Date: 4/01/16

End Date: 12/31/17

Abstract

Amines have been used for decades for the capture and removal of carbon dioxide in different chemical processes. The space of possible amines for this application is, however, very large, and exploring it poses a big challenge. In this work, we will develop computational techniques to carry out high-throughput screening of amines for carbon dioxide capture, and will also explore materials where the amine is immobilized in a polymer matrix, which might provide enhanced absorption and regeneration capabilities.

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EMN-15-S-01 Applications of Nanocellulose in Waterborne Coatings Systems

Eastman Chemical Company(1/01/16 - 12/31/18)

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EMN-15-S-01 Applications of Nanocellulose in Waterborne Coatings Systems

Sponsor: Eastman Chemical Company

Start Date: 1/01/16

End Date: 12/31/18

Abstract

We will use unmodified and chemically modified nanocellulose materials to develop rheology, dewatering and film formation routes that will lead to films and coatings with target physical appearance, mechanical integrity and thermo-chemical and wetting properties. For this purpose we will use precursors from three different nanocelluloses: cellulose nanocrystals (CNC), cellulose nanofibrils (CNF) and lignocellulose nanofibrils (LCNF).

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EMN-14-F-S-06: Phase-Change Gels Designed for Laminated Products for Use in Home and Office Settings

Eastman Chemical Company(1/01/16 - 3/31/17)

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EMN-14-F-S-06: Phase-Change Gels Designed for Laminated Products for Use in Home and Office Settings

Sponsor: Eastman Chemical Company

Start Date: 1/01/16

End Date: 3/31/17

Abstract

EMN-14-F-S-06 Phase-Change Gels Designed for Laminated Products for Use in Home and Office Settings Phase change materials (PCMs) constitute a broad class of chemical compounds that typically undergo a first-order phase transition (e.g., melting/freezing or evaporation/ condensation) at a temperature that lies near a target value for a given application. Associated with this thermodynamically-reversible transition is a latent heat that must be overcome before a rise or fall in temperature proceeds. In this fashion, the PCM can be used effectively to extract heat from (and thus cool) a warm body or provide heat to a cool body. For illustrative purposes, consider a PCM that is heated from a temperature below its transition temperature. Initially, the temperature of the PCM increases according to its heat capacity, which is a material property that relates a change in heat to the corresponding change in temperature. Once the PCM reaches its transition temperature, however, it remains isothermal until it fully undergoes its phase transition. Beyond this temperature, the PCM continues to change temperature with a new, higher heat capacity. This series of events is schematically depicted in Figure 1. As is evident from this heating scenario, an effective PCM must possess (1) a target-specific transition temperature, (2) a relatively high latent heat to absorb/emit heat under isothermal conditions, and (3) relatively high heat capacities to absorb heat without changing temperature significantly above and below the transition temperature. Another consideration is the extent of thermal expansion at temperatures lower than and above the thermal transition, as well as at the transition itself. For this reason, while high latent heats can be best achieved with PCMs designed to possess an evaporation/condensation transition, the associated volume increase and likelihood of losing PCM vapor from a reusable thermal comfort system preclude such materials from further consideration. Challenges in the use of PCMs that activate upon melting/freezing include incorporating the mass required to achieve adequate performance under target conditions, heat transfer limitations and the degree of cooling required to induce freezing (along with crystallization kinetics). To avoid complications due to melting of the PCM, we intend to use a technology derived from thermoplastic elastomers wherein the PCM is incorporated into the matrix of the TPE. In this manner, melting of the PCM results in a thermodynamically stable gel that does not flow. To improve heat transfer, the PCMs will be modified with thermally conductive nanoparticles at concentrations above the percolation threshold to expedite thermal conduction. For this reason, we refer to these hybrid nanomaterials as Phase-Change Elastomer Nanocomposites (PCENs). Promising and economically viable conductive nanoparticles for use in this design include high-aspect-ratio silver nanowires, which tend to possess relatively low percolation thresholds (ca. 1 wt%). Analysis of these materials sandwiched between polymers of interest to Eastman (e.g., Tritan) will be conducted to ascertain the cooling/heating efficiency of such laminates for use in homes and/or automobiles.

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EMN-13-F-S-06 Structure-Property-Process Relationships for Polyester Polyols

Eastman Chemical Company(12/01/14 - 8/31/18)

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EMN-13-F-S-06 Structure-Property-Process Relationships for Polyester Polyols

Sponsor: Eastman Chemical Company

Start Date: 12/01/14

End Date: 8/31/18

Abstract

As new polyester polyols chemistries are being synthesized for use in various coating applications, there is a strong need to understand how material chemistry affects crosslinking/curing of these systems and final film/solid properties. This project, involving experiments and molecular modeling, is geared towards providing a rational guideline to correlate molecular level chemistries to macro and micro characteristics.

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Magnetically-Driven Orientation of Multiphase Polymer Systems: A Ligand-Functionalized, Magnetic Nanoparticle Approach

National Science Foundation (NSF)(5/01/10 - 4/30/14)

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Magnetically-Driven Orientation of Multiphase Polymer Systems: A Ligand-Functionalized, Magnetic Nanoparticle Approach

Sponsor: National Science Foundation (NSF)

Start Date: 5/01/10

End Date: 4/30/14

Abstract

There is a great interest in dispersing nanoparticles in polymers for enhancing their mechanical, optical, electrical, and magnetic properties. The research objective of this proposal is to demonstrate the feasibility of using field-aligned surface-functionalized magnetic nanoparticles (NPs) to generate new multiphase polymeric materials with potentially new properties. The effects of magnetic NP chains formed in homogeneous polymer mixtures by externally applied, uniform magnetic fields, on the microstructure and morphology during (micro)phase separation (upon cooling or solvent removal) will be explored in two systems, polymer blends and block copolymers of poly(styrene)/poly(methyl methacrylate) (PS/PMMA). We hypothesize the magnetic-field driven formation of oriented lamellar structures with unusually large grain sizes. Nanoparticle surfaces with native long-chained aliphatic functional groups are expected to agglomerate at the interface serving as stabilizing sites. This prediction will first be verified using non-magnetic (Au) NPs, and then controlled formation of oriented interfaces will be attempted using magnetic (Fe3O4 and FePt) NPs under magnetic fields of up to 20 kOe to induce formation of linear NP chains. These NP chains are predicted to template formation of the interface through their pinning behavior. For exploring a different regime of thermodynamic behavior, NPs will be functionalized with oligostyrene (PS) or oligo(methyl methacrylate) (OMMA) to impart selective solubility in one of the polymer constituents. The microstructures and morphologies of field-controlled (micro)phase separation will be compared for magnetic NP chain formation at the interface versus within one of the constituents. Binary core Au/Fe3O4 NPs will also be prepared. Owing to the distinct Au and Fe3O4 surface chemistries, each half will be independently functionalized ? one half with OPS, and the other with OMMA. The possibility or forming interfaces with oriented Au/Fe3O4 NPs will be explored. Multiscale molecular dynamics simulations complementing experiments will be performed to provide a theoretical framework of the dynamics of interfacial assembly and to guide experimental design.

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In-Plane Nanostructural Organization of Copolymer Molecules Along Polymer/Polymer Interfaces

National Science Foundation (NSF)(8/01/08 - 7/31/10)

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In-Plane Nanostructural Organization of Copolymer Molecules Along Polymer/Polymer Interfaces

Sponsor: National Science Foundation (NSF)

Start Date: 8/01/08

End Date: 7/31/10

Abstract

Incorporation of an AB diblock copolymer into a thin polymer film alters the rate and mechanism by which the film dewets from an immiscible polymer substrate. Films of constant thickness with little or no AB dewet from the substrate by nucleation and growth of circular holes. Increasing the AB content creates a chemically and structurally heterogeneous interface and promotes spinodal-like dewetting wherein the fastest growing wave vector scales with time (t) as t^−0.332±0.004. This behavior is identical to that observed for spinodal decomposition of polymer blends and spinodal dewetting of ultrathin polymer films. Our materials, however, do not vary in film thickness and therefore fundamentally differ from systems that undergo spinodal dewetting. At higher AB concentration, dewetting is initially inhibited but eventually proceeds by the formation of noncircular flower-shaped holes. This proposed project would build on these exciting new findings that show tremendous promise as a means by which to marry the established use of block copolymers as compatibilizing agents and the predicted potential of using interfacial heterogeneities to tune the mechanism and rate of thin film destabilization.

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Processing and Characterization of Nanofiber - PVC Soft Composite for Electronic Applications

National Science Foundation (NSF)(4/01/07 - 12/31/11)

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Processing and Characterization of Nanofiber - PVC Soft Composite for Electronic Applications

Sponsor: National Science Foundation (NSF)

Start Date: 4/01/07

End Date: 12/31/11

Abstract

Polymeric nanocomposites that are filled with conducting nanoparticles have attracted considerable scientific and commercial interest in recent years because of their wide ranging potential and availability as new functional materials. The objective of the proposed research is to fabricate lightweight, conformable sensory materials that are compatible with electronic textile products including body-worn sensors. The proposal aims to use screen-printing to fabricate an elastic and conductive nanocomposite layer of plastisol, plasticized poly(vinyl chloride) (PVC), and carbon nanofiber (CNF) on existing textile fabrics to produce a piezoresistive strain-sensing fabric. Our overarching objective of developing a fabric sensor composite (FSC) is based on the hypothesis that an elastomeric layer containing conducting nanoparticles printed on fabric substrates can yield a flexible, piezoresistive coating that can be tailored for specific applications. The objective is also based on the premise that lightweight sensory materials can be produced by controlling the volume fraction of CNF relative to the percolation threshold at which the insulating polymer layer transitions into a conducting medium. The novelty of the proposed research lies in the use of PVC in the form of plastisol and CNF. Plastisol is a commercially available dispersion of PVC resin in a plasticizer that provides unique and tunable print properties. Fractionated CNFs, on the other hand, are well-suited to the fabrication of FSCs since they are more easily dispersed, less expensive and less rigid than their carbon nanotube (CNT) analogs. In addition, the proposed method of application, screen-printing, is a well understood process that can be readily adapted to the general development of conformable self-monitoring systems and, more specifically, FSCs. The scope of the project proposed here includes the following: (1) dispersion of CNFs in plasticized PVC by reported and novel methods, (2) characterization of CNF/PVC nanocomposites varying in CNF diameter, aspect ratio, concentration and dispersion route to determine the percolation threshold and piezoresistive response, (3) application and drying of the CNF/PVC nanocomposites on fabric surfaces to determine adhesion, wettability and electro-mechanical properties, and (4) examination of the resultant FSCs by advanced microscopy methods to elucidate the distribution and orientation of the CNFs under the same conditions listed in (2).

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Nanostructures in Copolymer Materials: Synthesizing a Predictive Model from Experimental 3-D Imaging

Center for Integrated Nanotechnologies (CINT)(10/16/06 - 10/15/07)

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Nanostructures in Copolymer Materials: Synthesizing a Predictive Model from Experimental 3-D Imaging

Sponsor: Center for Integrated Nanotechnologies (CINT)

Start Date: 10/16/06

End Date: 10/15/07

Abstract

The overarching objective of this work is to combine the theoretical expertise of scientists at LANL/CINT and the experimental efforts of researchers at North Carolina State University (NCSU) to develop physically accurate models that can provide predictive guidance for the design of multicomponent systems composed of self-organized block copolymers. Such systems are commonly employed in various contemporary and emergent (nano)technologies, but design paradigms have not been generally established for realistic systems. We intend to obtain the Ginzburg-Landau (GL) free energy coefficients for model copolymer materials from analysis of transmission electron microtomography (TEMT) data in the early stages of microphase separation and then project a computational model of the system forward to an equilibrated morphology. Achieving this objective will result in a clear evaluation of the terms needed in the GL model to capture the microphase-separated morphology. More significantly, meeting this objective will prove that a rapid screening capability could be developed in the future to predict the equilibrated morphology of new chemistries with limited experimental expenditure.

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Utilization of Transmission Electron Microtomography (TEMT)

National Institute of Standards & Technology(8/25/06 - 8/24/07)

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Utilization of Transmission Electron Microtomography (TEMT)

Sponsor: National Institute of Standards & Technology

Start Date: 8/25/06

End Date: 8/24/07

Abstract

Block copolymers (BCs) continue to receive attention as integral constituents of potential and realized nanotechnologies. In many of these envisaged roles, the nanostructures formed by self-organized BCs require controlled morphological orientation or development. Previous efforts seeking to achieve these objectives have relied on thermal and/or solvent tempering, as well as externally imposed shear or electrical fields. In this project, an alternative method of directing nanostructure development is proposed wherein a low-molar-mass organic templating agent (OTA) also capable of self-organization is physically added to the copolymer. The OTA of interest here is 1,3:2,4 dibenzylidene sorbitol, an amphiphilic molecule capable of forming shear-sensitive networks and solidifying organic solvents and soft polymers at relatively low concentrations (typically < 5 wt%). Depending on factors such as composition and copolymer incompatibility, two scenarios may result upon cooling molecular BC/OTA solutions from elevated temperatures: (1) the BC microphase-orders first and directs the OTA nanostructure, or (2) the OTA self-organizes first and directs the BC nanostructure. A series of diblock copolymers possessing variable incompatibility (as evidenced by their order-disorder transitions, ODTs) has been synthesized to examine these two scenarios. In collaboration with Drs. A. Karim and J.F. Douglas, we intend to conduct a systematic investigation of BC/OTA blends differing in BC incompatibility and OTA concentration to discern the effects of the two scenarios described above. Morphological investigation of blends prepared under quiescent and shear conditions will be conducted by polarized light microscopy, transmission electron microscopy/microtomography and small-angle scattering.

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