@article{mineart_ryan_appavou_lee_gradzielski_spontak_2019, title={Self-Assembly of a Midblock-Sulfonated Pentablock Copolymer in Mixed Organic Solvents: A Combined SAXS and SANS Analysis}, volume={35}, ISSN={["0743-7463"]}, DOI={10.1021/acs.langmuir.8b03825}, abstractNote={Ionic, and specifically sulfonated, block copolymers are continually gaining interest in the soft materials community due to their unique suitability in various ion-exchange applications such as fuel cells, organic photovoltaics, and desalination membranes. One unresolved challenge inherent to these materials is solvent templating, that is, the translation of self-assembled solution structures into nonequilibrium solid film morphologies. Recently, the use of mixed polar/nonpolar organic solvents has been examined in an effort to elucidate and control the solution self-assembly of sulfonated block copolymers. The current study sheds new light on micellar assemblies (i.e., those with the sulfonated blocks comprising the micellar core) of a midblock-sulfonated pentablock copolymer in polar/nonpolar solvent mixtures by combining small-angle X-ray and small-angle neutron scattering. Our scattering data reveal that micelle size depends strongly on overall solvent composition: micelle cores and coronae grow as the fraction of nonpolar solvent is increased. Universal model fits further indicate that an unexpectedly high fraction of the micelle cores is occupied by polar solvent (60-80 vol %) and that partitioning of the polar solvent into micelle cores becomes more pronounced as its overall quantity decreases. This solvent presence in the micelle cores explains the simultaneous core/corona growth, which is otherwise counterintuitive. Our findings provide a potential pathway for the formation of solvent-templated films with more interconnected morphologies due to the greatly solvated micellar cores in solution, thereby enhancing the molecular, ion, and electron-transport properties of the resultant films.}, number={4}, journal={LANGMUIR}, author={Mineart, Kenneth P. and Ryan, Justin J. and Appavou, Marie-Sousai and Lee, Byeongdu and Gradzielski, Michael and Spontak, Richard J.}, year={2019}, month={Jan}, pages={1032–1039} }
 @article{cai_mineart_li_spontak_manners_qiu_2018, title={Hierarchical Self-Assembly of Toroidal Micelles into Multidimensional Nanoporous Superstructures}, volume={7}, ISSN={["2161-1653"]}, DOI={10.1021/acsmacrolett.8b00445}, abstractNote={Materials with controlled porosity play a prominent role in industrial and domestic applications. Although a rich array of methods has been developed to tune the pore size over a broad range (from <1 nm to >1 μm), the fabrication of functional materials with a fully open porous structure with sub-100 nm pore size has remained a significant challenge. Herein, we report the hierarchical assembly of block copolymer toroidal micelles with an intrinsic cavity into multidimensional nanoporous superstructures (pore size 85-90 nm) by modulation of interparticle interactions. The toroids aggregate into oligo-supermicelles or 2D hexagonal arrays through van der Waals interactions upon drying on a substrate, while synergistic hydrogen bonding interactions further promote the formation of 3D nanoporous superstructures directly in solution. Thus, toroidal micelles can be manipulated as a type of distinctive building block to construct nanoporous materials.}, number={8}, journal={ACS MACRO LETTERS}, author={Cai, Jiandong and Mineart, Kenneth P. and Li, Xiaoyu and Spontak, Richard J. and Manners, Ian and Qiu, Huibin}, year={2018}, month={Aug}, pages={1040–1045} }
 @article{deng_yan_tilly_deng_mineart_spontak_2018, title={Incorporation of Metallic Species into Midblock-Sulfonated Block Ionomers}, volume={39}, ISSN={["1521-3927"]}, DOI={10.1002/marc.201800427}, abstractNote={Abstract}, number={22}, journal={MACROMOLECULAR RAPID COMMUNICATIONS}, publisher={Wiley}, author={Deng, Jing and Yan, Jiaqi and Tilly, Joseph C. and Deng, Liyuan and Mineart, Kenneth P. and Spontak, Richard J.}, year={2018}, month={Nov} }
 @article{an_huang_mineart_dong_spontak_gubbins_2017, title={Adhesion and friction in polymer films on solid substrates: conformal sites analysis and corresponding surface measurements}, volume={13}, ISSN={1744-683X 1744-6848}, url={http://dx.doi.org/10.1039/C7SM00261K}, DOI={10.1039/c7sm00261k}, abstractNote={In this work, we present a statistical mechanical analysis to elucidate the molecular-level factors responsible for the static and dynamic properties of polymer films. This analysis, which we term conformal sites theory, establishes that three dimensionless parameters play important roles in determining differences from bulk behavior for thin polymer films near to surfaces: a microscopic wetting parameter, αwx, defined as the ratio of polymer-substrate interaction to polymer-polymer interaction; a dimensionless film thickness, H*; and dimensionless temperature, T*. The parameter αwx introduced here provides a more fundamental measure of wetting than previous metrics, since it is defined in terms of intermolecular forces and the atomic structure of the substrate, and so is valid at the nanoscale for gas, liquid or solid films. To test this theoretical analysis, we also report atomic force microscopy measurements of the friction coefficient (μ), adhesion force (FA) and glass transition temperature (Tg) for thin films of two polymers, poly(methyl methacrylate) (PMMA) and polystyrene (PS), on two planar substrates, graphite and silica. Both the friction coefficient and the glass transition temperature are found to increase as the film thickness decreases, and this increase is more pronounced for the graphite than for the silica surface. The adhesion force is also greater for the graphite surface. The larger effects encountered for the graphite surface are attributed to the fact that the microscopic wetting parameter, αwx, is larger for graphite than for silica, indicating stronger attraction of polymer chains to the graphite surface.}, number={19}, journal={Soft Matter}, publisher={Royal Society of Chemistry (RSC)}, author={An, Rong and Huang, Liangliang and Mineart, Kenneth P. and Dong, Yihui and Spontak, Richard J. and Gubbins, Keith E.}, year={2017}, pages={3492–3505} }
 @article{mineart_dickerson_love_lee_zuo_spontak_2017, title={Hydrothermal Conditioning of Physical Hydrogels Prepared from a Midblock-Sulfonated Multiblock Copolymer}, volume={38}, ISSN={["1521-3927"]}, DOI={10.1002/marc.201600666}, abstractNote={Since nanostructured amphiphilic macromolecules capable of affording high ion and water transport are becoming increasingly important in a wide range of contemporary energy and environmental technologies, the swelling kinetics and temperature dependence of water uptake are investigated in a series of midblock‐sulfonated thermoplastic elastomers. Upon self‐assembly, these materials maintain a stable hydrogel network in the presence of a polar liquid. In this study, real‐time water‐sorption kinetics in copolymer films prepared by different casting solvents are elucidated by synchrotron small‐angle X‐ray scattering and gravimetric measurements, which directly correlate nanostructural changes with macroscopic swelling to establish fundamental structure–property behavior. By monitoring the equilibrium swelling capacity of these materials over a range of temperatures, an unexpected transition in the vicinity of 50 °C has been discovered. Depending on copolymer morphology and degree of sulfonation, hydrothermal conditioning of specimens to temperatures above this transition permits retention of superabsorbent swelling at ambient temperature.
image}, number={5}, journal={MACROMOLECULAR RAPID COMMUNICATIONS}, author={Mineart, Kenneth P. and Dickerson, Joshua D. and Love, Dillon M. and Lee, Byeongdu and Zuo, Xiaobing and Spontak, Richard J.}, year={2017}, month={Mar} }
 @article{mineart_ryan_lee_smith_spontak_2017, title={Molecular and Morphological Characterization of Midblock-Sulfonated Styrenic Triblock Copolymers}, volume={55}, ISSN={["1099-0488"]}, DOI={10.1002/polb.24294}, abstractNote={ABSTRACT}, number={6}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Mineart, Kenneth P. and Ryan, Justin J. and Lee, Byeongdu and Smith, Steven D. and Spontak, Richard J.}, year={2017}, month={Mar}, pages={490–497} }
 @article{al-mohsin_mineart_armstrong_spontak_2017, title={Tuning the performance of aqueous photovoltaic elastomer gels by solvent polarity and nanostructure development}, volume={55}, ISSN={["1099-0488"]}, DOI={10.1002/polb.24242}, abstractNote={In this study, a sulfonated pentablock ionomer is considered for use as an aqueous gel electrolyte in photovoltaic elastomer gels (PVEGs) containing photosensitive dyes. Depending on the casting solvent employed, these materials order into different nanoscale morphologies, some of which inherently consist of a continuous pathway through which ions and other polar species are able to diffuse, while others transform into continuous channels upon exposure to water. Here, we examine the effect of solvent polarity during film casting, vapor annealing, and liquid immersion on block ionomer morphology and PVEG photovoltaic performance. Casting the block ionomers from a mixed nonpolar/polar solvent promotes the formation of dispersed ion-rich spherical microdomains. Alternatively, the use of a single polar solvent produces coexisting nonpolar cylinders and lamellae. Exposure of either morphology to polar solvent vapor causes the block ionomers to restructure into a lamellar morphology, whereas exposure of dispersed ion-rich microdomains to water induces a transformation to an irregular morphology composed of continuous ionic channels, which provide an effective pathway for ion diffusion and, consequently, the highest photovoltaic efficiency. In addition to their photovoltaic efficacy, these aqueous gels possess improved mechanical properties (in terms of tensile strength and elastic modulus) in the presence of photosensitive dyes. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016}, number={1}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Al-Mohsin, Heba A. and Mineart, Kenneth P. and Armstrong, Daniel P. and Spontak, Richard J.}, year={2017}, month={Jan}, pages={85–95} }
 @article{mineart_lee_spontak_2016, title={A Solvent-Vapor Approach toward the Control of Block lonomer Morphologies}, volume={49}, ISSN={["1520-5835"]}, DOI={10.1021/acs.macromol.6b00134}, abstractNote={Sulfonated block ionomers possess advantageous properties for a wide range of diverse applications such as desalination membranes, fuel cells, electroactive media, and photovoltaic devices. Unfortunately, their inherently high incompatibilities and glass transition temperatures effectively prevent the use of thermal annealing, routinely employed to refine the morphologies of nonionic block copolymers. An alternative approach is therefore required to promote morphological equilibration in block ionomers. The present study explores the morphological characteristics of midblock-sulfonated pentablock ionomers (SBIs) differing in their degree of sulfonation (DOS) and cast from solution followed by solvent-vapor annealing (SVA). Transmission electron microscopy confirms that films deposited from different solvent systems form nonequilibrium morphologies due to solvent-regulated self-assembly and drying. A series of SVA tests performed with solvents varying in polarity reveals that exposing cast films to tetrahy...}, number={8}, journal={MACROMOLECULES}, author={Mineart, Kenneth P. and Lee, Byeongdu and Spontak, Richard J.}, year={2016}, month={Apr}, pages={3126–3137} }
 @article{armstrong_mineart_lee_spontak_2016, title={Olefinic Thermoplastic Elastomer Gels: Combining Polymer Crystallization and Microphase Separation in a Selective Solvent}, volume={5}, ISSN={["2161-1653"]}, DOI={10.1021/acsmacrolett.6b00677}, abstractNote={Since selectively swollen thermoplastic elastomer gels (TPEGs) afford a wide range of beneficial properties that open new doors to developing elastomer-based technologies, we examine the unique structure-property behavior of TPEGs composed of olefinic block copolymers (OBCs) in this study. Unlike their styrenic counterparts typically possessing two chemically different blocks, this class of multiblock copolymers consists of linear polyethylene hard blocks and poly(ethylene-co-α-octene) soft blocks, in which case, microphase separation between the hard and the soft blocks is accompanied by crystallization of the hard blocks. Here, we prepare olefinic TPEGs (OTPEGs) through the incorporation of a primarily aliphatic oil that selectively swells the soft block and investigate the resultant morphological features through the use of polarized light microscopy and small-/wide-angle X-ray scattering. These features are correlated with thermal and mechanical property measurements from calorimetry, rheology, and extensiometry to elucidate the roles of crystallization and self-assembly on gel characteristics and establish useful structure-property relationships.}, number={11}, journal={ACS MACRO LETTERS}, author={Armstrong, Daniel P. and Mineart, Kenneth P. and Lee, Byeongdu and Spontak, Richard J.}, year={2016}, month={Nov}, pages={1273–1277} }
 @article{mineart_tallury_li_lee_spontak_2016, title={Phase-Change Thermoplastic Elastomer Blends for Tunable Shape Memory by Physical Design}, volume={55}, ISSN={["0888-5885"]}, DOI={10.1021/acs.iecr.6b04039}, abstractNote={Intelligent polymeric materials are of increasing interest in contemporary technologies due to their low cost, light weight, facile processability, and inherent ability to change properties, shape, and/or size upon exposure to an external stimulus. In this study, we consider thermally programmable shape-memory polymers (SMPs), which typically rely on chemistry-specific macromolecules composed of two functional species. An elastic, network-forming component permits stretched polymer chains to return to their relaxed state, and a switching component affords at least one thermal transition to regulate fixation of a desired strain state and return to a previous strain state. Here, we produce designer shape-memory materials by combining thermoplastic elastomeric triblock copolymers with a midblock-selective phase-change additive, thereby yielding shape-memory polymer blends (SMPBs). These materials not only exhibit tunable switch points but also controllable recovery kinetics. We further highlight the versatil...}, number={49}, journal={INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH}, author={Mineart, Kenneth P. and Tallury, Syamal S. and Li, Tao and Lee, Byeongdu and Spontak, Richard J.}, year={2016}, month={Dec}, pages={12590–12597} }
 @article{mineart_al-mohsin_lee_spontak_2016, title={Water-induced nanochannel networks in self-assembled block ionomers}, volume={108}, ISSN={["1077-3118"]}, DOI={10.1063/1.4943505}, abstractNote={Block ionomers cast from solution exhibit solvent-templated morphologies that can be altered by solvent-vapor annealing. When cast from a mixed solvent, a midblock-sulfonated pentablock ionomer self-assembles into spherical ionic microdomains that are loosely connected. Upon exposure to liquid water, nanoscale channels irreversibly develop between the microdomains due to swelling and form a continuous mesoscale network. We use electron tomography and real-time X-ray scattering to follow this transformation and show that the resultant morphology provides a highly effective diffusive pathway.}, number={10}, journal={APPLIED PHYSICS LETTERS}, author={Mineart, Kenneth P. and Al-Mohsin, Heba A. and Lee, Byeongdu and Spontak, Richard J.}, year={2016}, month={Mar} }
 @article{woloszczuk_mineart_spontak_banaszak_2015, title={Dual modes of self-assembly in superstrongly segregated bicomponent triblock copolymer melts}, volume={91}, ISSN={["1550-2376"]}, DOI={10.1103/physreve.91.010601}, abstractNote={While ABC triblock copolymers are known to form a plethora of dual-mode (i.e., order-on-order) nanostructures, bicomponent ABA triblock copolymers normally self-assemble into single morphologies at thermodynamic incompatibility levels up to the strong-segregation regime. In this study, we employ on-lattice Monte Carlo simulations to examine the phase behavior of molecularly asymmetric A(1)BA(2) copolymers possessing chemically identical endblocks differing significantly in length. In the limit of superstrong segregation, interstitial micelles composed of the minority A(2) endblock are observed to arrange into two-dimensional hexagonal arrays along the midplane of B-rich lamellae in compositionally symmetric (50:50 A:B) copolymers. Simulations performed here establish the coupled molecular-asymmetry and incompatibility conditions under which such micelles form, as well as the temperature dependence of their aggregation number. Beyond an optimal length of the A(2) endblock, the propensity for interstitial micelles to develop decreases, and the likelihood for colocation of both endblocks in the A(1)-rich lamellae increases. Interestingly, the strong-segregation theory of Semenov developed to explain the formation of free micelles by diblock copolymers accurately predicts the onset of interstitial micelles confined at nanoscale dimensions between parallel lamellae.}, number={1}, journal={PHYSICAL REVIEW E}, author={Woloszczuk, Sebastian and Mineart, Kenneth P. and Spontak, Richard J. and Banaszak, Michal}, year={2015}, month={Jan} }
 @article{al-mohsin_mineart_spontak_2015, title={Highly Flexible Aqueous Photovoltaic Elastomer Gels Derived from Sulfonated Block Ionomers}, volume={5}, ISSN={["1614-6840"]}, DOI={10.1002/aenm.201401941}, abstractNote={H. A. Al-Mohsin Fiber and Polymer Science Program North Carolina State University Raleigh , NC 27695 , USA K. P. Mineart, Prof. R. J. Spontak Department of Chemical and Biomolecular Engineering North Carolina State University Raleigh , NC 27695 , USA E-mail: Rich_Spontak@ncsu.edu Prof. R. J. Spontak Department of Materials Science & Engineering North Carolina State University Raleigh , NC 27695 , USA}, number={8}, journal={ADVANCED ENERGY MATERIALS}, author={Al-Mohsin, Heba A. and Mineart, Kenneth P. and Spontak, Richard J.}, year={2015}, month={Apr} }
 @article{mineart_jiang_jinnai_takahara_spontak_2015, title={Morphological Investigation of Midblock-Sulfonated Block Ionomers Prepared from Solvents Differing in Polarity}, volume={36}, ISSN={["1521-3927"]}, DOI={10.1002/marc.201400627}, abstractNote={Recent developments regarding charged multiblock copolymers that can form physical networks and exhibit robust mechanical properties herald new and exciting opportunities for contemporary technologies requiring amphiphilic attributes. Due to the presence of strong interactions, however, control over the phase behavior of such materials remains challenging, especially since their morphologies can be solvent‐templated. In this study, transmission electron microscopy and microtomography are employed to examine the morphological characteristics of midblock‐sulfonated pentablock ionomers prepared from solvents differing in polarity. Resultant images confirm that discrete, spherical ion‐rich microdomains form in films cast from a relatively nonpolar solvent, whereas an apparently mixed morphology with a continuous ion‐rich pathway is generated when the casting solvent is more highly polar. Detailed 3D analysis of the morphological characteristics confirms the coexistence of hexagonally‐packed nonpolar cylinders and lamellae, which facilitates the diffusion of ions and/or other polar species through the nanostructured medium.
image}, number={5}, journal={MACROMOLECULAR RAPID COMMUNICATIONS}, author={Mineart, Kenneth P. and Jiang, Xi and Jinnai, Hiroshi and Takahara, Atsushi and Spontak, Richard J.}, year={2015}, month={Mar}, pages={432–438} }
 @article{tallury_mineart_woloszczuk_williams_thompson_pasquinelli_banaszak_spontak_2014, title={Communication: Molecular-level insights into asymmetric triblock copolymers: Network and phase development}, volume={141}, ISSN={["1089-7690"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-84907545888&partnerID=MN8TOARS}, DOI={10.1063/1.4896612}, abstractNote={Molecularly asymmetric triblock copolymers progressively grown from a parent diblock copolymer can be used to elucidate the phase and property transformation from diblock to network-forming triblock copolymer. In this study, we use several theoretical formalisms and simulation methods to examine the molecular-level characteristics accompanying this transformation, and show that reported macroscopic-level transitions correspond to the onset of an equilibrium network. Midblock conformational fractions and copolymer morphologies are provided as functions of copolymer composition and temperature.}, number={12}, journal={JOURNAL OF CHEMICAL PHYSICS}, publisher={AIP Publishing}, author={Tallury, Syamal S. and Mineart, Kenneth P. and Woloszczuk, Sebastian and Williams, David N. and Thompson, Russell B. and Pasquinelli, Melissa A. and Banaszak, Michal and Spontak, Richard J.}, year={2014}, month={Sep} }
 @article{tallury_mineart_woloszczuk_williams_thompson_pasquinelli_banaszak_spontak_2014, title={Communication: Molecular-level insights into asymmetric triblock copolymers: Network and phase development (vol 141, 121103, 2014)}, volume={141}, ISSN={["1089-7690"]}, url={https://doi.org/10.1063/1.4898353}, DOI={10.1063/1.4898353}, abstractNote={First Page}, number={16}, journal={JOURNAL OF CHEMICAL PHYSICS}, publisher={AIP Publishing}, author={Tallury, Syamal S. and Mineart, Kenneth P. and Woloszczuk, Sebastian and Williams, David N. and Thompson, Russell B. and Pasquinelli, Melissa A. and Banaszak, Michal and Spontak, Richard J.}, year={2014}, month={Oct} }