@article{stevens_thongruang_patel_smith_spontak_2003, title={Solvent-facilitated homopolymer sorption in swollen block copolymer matrices}, volume={36}, ISSN={["1520-5835"]}, DOI={10.1021/ma0215868}, abstractNote={Homopolymer sorption in microphase-ordered block copolymers can provide insight into the factors governing transport of chain molecules in dense nanostructured environments, as well as yield novel nonequilibrium materials. Here, we examine the sorption of homopolymer B (hB) in ABA triblock copolymers swollen in a B-selective solvent. Gravimetric analysis reveals that the solubility of hB (ShB) varies linearly with solution concentration (C) and that (∂ShB/∂C)T depends on the molecular weight of the B midblock (MB). These data also show that the effective diffusion coefficient of hB is ∼10-8 cm2/s, independent of MB.}, number={9}, journal={MACROMOLECULES}, author={Stevens, JE and Thongruang, W and Patel, NP and Smith, SD and Spontak, RJ}, year={2003}, month={May}, pages={3206–3209} }
 @article{leonard_spontak_smith_russell_2002, title={Topological coarsening of low-molecular-weight block copolymer ultrathin films by environmental AFM}, volume={43}, ISSN={["0032-3861"]}, DOI={10.1016/S0032-3861(02)00640-7}, abstractNote={Topological coarsening of block copolymer ultrathin films is well-understood for copolymers exhibiting intermediate or strong segregation and differing in film thickness or molecular weight at temperatures above the upper glass transition temperature (Tg), but below the order–disorder transition (TODT), of the copolymers. More recent studies suggest that the stability and topology of such films differ at temperatures above TODT. In this work, we use environmental atomic force microscopy to examine the effect of temperature on the coarsening of block copolymer ultrathin films in situ. Films measuring ca. 25 nm thick consist of a low-molecular-weight poly(styrene-b-isoprene) diblock copolymer for which the upper Tg and TODT in the bulk are about 42 and 70 °C, respectively. Time-resolved image sequences illustrating surface reorganization are obtained at temperatures below, above and near 70 °C. At temperatures very close to 70 °C, coarsening is found to slow markedly, by almost an order of magnitude relative to what is observed at higher and lower temperatures, suggesting that thermal factors may provide a means by which to inhibit the dewetting of block copolymer ultrathin films.}, number={25}, journal={POLYMER}, author={Leonard, DN and Spontak, RJ and Smith, SD and Russell, PE}, year={2002}, month={Dec}, pages={6719–6726} }
 @article{jinnai_nishikawa_ito_smith_agard_spontak_2002, title={Topological similarity of sponge-like bicontinuous morphologies differing in length scale}, volume={14}, ISSN={["1521-4095"]}, DOI={10.1002/1521-4095(20021118)14:22<1615::AID-ADMA1615>3.0.CO;2-S}, abstractNote={Sponge-like bicontinuous morphologies (see Figure and also cover) are ubiquitous in the physical and biological sciences, but are only qualitatively understood in terms of their structure. Here, 3D imaging techniques are used to explore the characteristics of such morphologies at the nanoscale, microscale, and macroscale. Comparison of local and global topology metrics provides quantitative evidence of similarities between these morphologies.}, number={22}, journal={ADVANCED MATERIALS}, author={Jinnai, H and Nishikawa, Y and Ito, M and Smith, SD and Agard, DA and Spontak, RJ}, year={2002}, month={Nov}, pages={1615–1618} }
 @article{smith_ade_smith_koch_spontak_2001, title={Anomalous phase inversion in polymer blends prepared by cryogenic mechanical alloying}, volume={34}, ISSN={["1520-5835"]}, DOI={10.1021/ma001151p}, abstractNote={offer alternative strategies for producing highly dis-persed multicomponent polymer blends. By their verynature, these processes yield fine powders, which mustbe subsequently consolidated or melt-processed to formobjects. While nanoscale dispersion of one polymerwithin the matrix of another has been achieved withoutcompatibilizing agents in binary blends produced byCMA,}, number={6}, journal={MACROMOLECULES}, author={Smith, AP and Ade, H and Smith, SD and Koch, CC and Spontak, RJ}, year={2001}, month={Mar}, pages={1536–1538} }
 @article{spontak_wilder_smith_2001, title={Improved network development in bidisperse AB/ABA block copolymer gels}, volume={17}, ISSN={["0743-7463"]}, DOI={10.1021/la0015819}, abstractNote={Blending a B-selective solvent and an ordered ABA triblock copolymer can, at sufficiently high solvent concentrations, produce a physical gel composed of a network of B midblocks stabilized by A-rich micelles. We demonstrate here that addition of short AB diblock copolymer molecules to such a gel at constant copolymer composition can enhance the solid-like character of the gel, as indicated by an increase in the magnitude of the dynamic elastic modulus. Similarly, addition of AB molecules to a nongelled ABA/solvent system can induce gelation. In light of recent theoretical predictions and related experimental evidence, these results are consistent with a scenario in which tail-induced volume exclusion (due to the presence of AB molecules) within the micellar coronas improves network development through an increase in the population of bridged B midblocks.}, number={8}, journal={LANGMUIR}, author={Spontak, RJ and Wilder, EA and Smith, SD}, year={2001}, month={Apr}, pages={2294–2297} }
 @article{kane_norman_white_matsen_satkowski_smith_spontak_2001, title={Molecular, nanostructural and mechanical characteristics of lamellar triblock copolymer blends: Effects of molecular weight and constraint}, volume={22}, ISSN={["1521-3927"]}, DOI={10.1002/1521-3927(20010301)22:5<281::AID-MARC281>3.0.CO;2-G}, abstractNote={While theoretical and experimental efforts have thoroughly addressed microphase-ordered AB diblock copolymer blends with a parent homopolymer (hA or hB) or a second block copolymer, surprisingly few studies have considered comparable ABA triblock copolymers in the presence of hB or an AB diblock copolymer. In this study, we elucidate the roles of additive molecular weight and constraint by examining three matched series of miscible ABA/hB and ABA/AB blends. Self-consistent field theory is employed to analyze molecular characteristics, e. g., segmental distributions, microdomain periods and midblock bridging fractions, as functions of blend composition. Predictions are compared to morphological characteristics discerned by transmission electron microscopy and small-angle X-ray scattering. The corresponding mechanical properties of these blends are measured by dynamic mechanical analysis. The results of this comprehensive work reveal that addition of hB swells the B-lamellae of the ABA copolymer and has a generally deleterious effect on both the dynamic elastic modulus and midblock bridging fraction. In contrast, addition of a lamellar or cylindrical AB copolymer to the same ABA copolymer can promote an increase or decrease in lamellar period and bridging fraction, depending on relative block sizes.}, number={5}, journal={MACROMOLECULAR RAPID COMMUNICATIONS}, author={Kane, L and Norman, DA and White, SA and Matsen, MW and Satkowski, MM and Smith, SD and Spontak, RJ}, year={2001}, month={Mar}, pages={281–296} }
 @article{spontak_smith_2001, title={Perfectly-alternating linear (AB)(n) multiblock copolymers: Effect of molecular design on morphology and properties}, volume={39}, ISSN={["0887-6266"]}, DOI={10.1002/polb.1070}, abstractNote={Abstract}, number={9}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={Spontak, RJ and Smith, SD}, year={2001}, month={May}, pages={947–955} }
 @article{smith_ade_koch_smith_spontak_2000, title={Addition of a block copolymer to polymer blends produced by cryogenic mechanical alloying}, volume={33}, ISSN={["0024-9297"]}, DOI={10.1021/ma9915475}, abstractNote={Cryogenic mechanical alloying is used to incorporate a poly(methyl methacrylate-b-isoprene) (MI) diblock copolymer into blends of poly(methyl methacrylate) (PMMA) and polyisoprene (PI). Mechanical milling of the copolymer promotes a reduction in the molar mass of the M block, as discerned from glass transition temperature measurements performed by thermal calorimetry, and induces chemical cross- linking of the I block, as determined from sol-gel analysis. These effects become more pronounced with increasing milling time. Morphological characterization of PMMA-rich PI/MI/PMMA blends by X-ray and electron microscopies reveals that the characteristic size scale of the minority phase decreases with increasing MI content, as well as milling time. The nanostructural features observed in such blends are retained at relatively high MI concentrations during subsequent melt-pressing. Impact testing demon- strates that the blends become tougher upon addition of the MI copolymer, even at relatively low copolymer concentrations. Blend toughness likewise increases with increasing milling time up to a point, beyond which phase inversion occurs within the ternary blends (the PI becomes continuous) and impact strength sharply decreases.}, number={4}, journal={MACROMOLECULES}, author={Smith, AP and Ade, H and Koch, CC and Smith, SD and Spontak, RJ}, year={2000}, month={Feb}, pages={1163–1172} }
 @article{smith_ade_balik_koch_smith_spontak_2000, title={Cryogenic mechanical alloying of poly(methyl methacrylate) with polyisoprene and poly(ethylene-alt-propylene)}, volume={33}, ISSN={["1520-5835"]}, DOI={10.1021/ma991453v}, abstractNote={Mechanical alloying is performed at cryogenic temperatures to incorporate polyisoprene (PI) or its hydrogenated analogue poly(ethylene-alt-propylene) (PEP) into poly(methyl methacrylate) (PMMA) as an example of high-energy solid-state blending. Morphological characterization of the blends by X-ray and electron microscopies confirms that the degree of dispersion of the constituent polymers improves with increasing milling time. Such dispersion in the PEP/PMMA blends is, however, ultimately compromised by phase coarsening when the materials are postprocessed above the PMMA glass transition temperature in the melt. Milling-induced PI cross-linking serves to suppress phase coarsening in PI/ PMMA blends, which remain relatively well-dispersed even after postprocessing. These blends are generally less fracture-resistant than the as-received PMMA due mainly to the accompanying reduction in PMMA molecular weight. Their optical transparency is observed to decrease dramatically with increasing PEP or PI concentration until they appear opaque. An overall improvement in blend properties by mechanical alloying is, however, anticipated upon judicious selection of more degradation-resistant polymers.}, number={7}, journal={MACROMOLECULES}, author={Smith, AP and Ade, H and Balik, CM and Koch, CC and Smith, SD and Spontak, RJ}, year={2000}, month={Apr}, pages={2595–2604} }
 @article{jinnai_nishikawa_spontak_smith_agard_hashimoto_2000, title={Direct measurement of interfacial curvature distributions in a bicontinuous block copolymer morphology}, volume={84}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.84.518}, abstractNote={Self-consistent field theory predicts that the complex phase behavior of block copolymers does not originate solely from the interface seeking constant mean curvature as once thought, but instead reflects competing minimization of interfacial tension and packing frustration. To test this prediction, we directly measure interfacial curvature distributions from a 3D image reconstruction of the bicontinuous gyroid morphology. Results obtained here reveal that the gyroid interface is not constant mean curvature and confirm the importance of packing frustration in the stabilization of such complex nanostructures.}, number={3}, journal={PHYSICAL REVIEW LETTERS}, author={Jinnai, H and Nishikawa, Y and Spontak, RJ and Smith, SD and Agard, DA and Hashimoto, T}, year={2000}, month={Jan}, pages={518–521} }
 @article{smith_shay_spontak_balik_ade_smith_koch_2000, title={High-energy mechanical milling of poly(methyl methacrylate), polyisoprene and poly(ethylene-alt-propylene)}, volume={41}, ISSN={["0032-3861"]}, DOI={10.1016/S0032-3861(99)00830-7}, abstractNote={High-energy mechanical milling has been performed on poly(methyl methacrylate) (PMMA) at ambient and cryogenic temperatures, as well as on polyisoprene (PI) and poly(ethylene-alt-propylene) (PEP) at cryogenic conditions only. Milling conducted at ambient temperature has a substantially greater impact on the molecular characteristics of PMMA than milling at cryogenic temperatures. An increase in the milling time is accompanied by substantial reductions in PMMA molecular weight and, hence, glass transition temperature and impact strength under both sets of experimental conditions. An unexpected trend identified here is that the PMMA molecular weight distribution initially broadens and subsequently narrows with increasing milling time. Solid-state mechanical milling promotes comparable decreases in molecular weight and glass transition temperature in PEP (at a slower rate relative to PMMA), but induces chemical crosslinking in PI, as confirmed by FTIR spectroscopy. Charlesby–Pinner analysis yields not only the degree of PI crosslinking, but also the relative crosslinking and scission rates of PI, during cryogenic milling.}, number={16}, journal={POLYMER}, author={Smith, AP and Shay, JS and Spontak, RJ and Balik, CM and Ade, H and Smith, SD and Koch, CC}, year={2000}, month={Jul}, pages={6271–6283} }
 @article{smith_spontak_koch_smith_ade_2000, title={Temperature-induced morphological evolution in polymer blends produced by cryogenic mechanical alloying}, volume={274}, DOI={10.1002/(sici)1439-2054(20000101)274:1<1::aid-mame1>3.3.co;2-r}, number={1}, journal={Macromolecular Materials and Engineering}, author={Smith, A. P. and Spontak, Richard and Koch, C. C. and Smith, S. D. and Ade, H.}, year={2000}, pages={1–12} }
 @article{walker_raghavan_royer_smith_wignall_melnichenko_khan_spontak_1999, title={Enhanced miscibility of low-molecular-weight polystyrene polyisoprene blends in supercritical CO2}, volume={103}, ISSN={["1089-5647"]}, DOI={10.1021/jp990551f}, abstractNote={While ongoing efforts continue to explore the high-pressure phase equilibria of polymer blends, few studies have attempted to address the impact of a supercritical (sc) fluid on such equilibria. In this work, we report on the phase behavior of an upper critical solution temperature (UCST) polymer blend in the presence of supercritical carbon dioxide (scCO2), a nonselective plasticizing agent. Blends composed of low-molecular-weight polystyrene and polyisoprene have been examined as a function of temperature in scCO2 by visual inspection, small-angle neutron scattering, and spectrophotometry. In the presence of scCO2, the cloud point temperature is depressed by as much as 28 °C, depending on both blend composition and CO2 pressure. Complementary studies performed with nitrogen decouple the plasticization efficacy of CO2 from free-volume compression due to hydrostatic pressure. Existence of a pressure yielding a maximum in CO2-induced cloud point depression is established. These results provide evidence for...}, number={26}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, author={Walker, TA and Raghavan, SR and Royer, JR and Smith, SD and Wignall, GD and Melnichenko, Y and Khan, SA and Spontak, RJ}, year={1999}, month={Jul}, pages={5472–5476} }
 @article{smith_spontak_ade_smith_koch_1999, title={High-energy cryogenic blending and compatibilizing of immiscible polymers}, volume={11}, ISSN={["1521-4095"]}, DOI={10.1002/(SICI)1521-4095(199910)11:15<1277::AID-ADMA1277>3.0.CO;2-9}, abstractNote={ciency Z in solid films of PA-PPV and MEH-PPV has been determined by xerographic discharge experiments over two orders of magnitude in field and for different illumination wavelengths. Onsager's theory with a Gaussian distribution of electron±hole radii describes the electric field dependences of Z well. The large distribution parameter a is a characteristic of a small electron±hole pair binding energy of approximately 0.1±0.2 eV. For both polymers, high efficiencies of up to 20 % at a field of 100 V/mm were measured. Within the polymer absorption, Z was found to be nearly independent of wavelength. This is in agreement with the well established picture of a fast vibronic and energetic relaxation following photoexcitation. Addition of C60 to PA-PPV increases the primary quantum yield to unity and photogeneration efficiencies of up to 50 % are measured.}, number={15}, journal={ADVANCED MATERIALS}, author={Smith, AP and Spontak, RJ and Ade, H and Smith, SD and Koch, CC}, year={1999}, month={Oct}, pages={1277-+} }
 @article{king_white_smith_spontak_1999, title={Mesogel networks via selective midblock swelling of lamellar triblock copolymers}, volume={15}, ISSN={["0743-7463"]}, DOI={10.1021/la9816407}, abstractNote={A lamellar ABA triblock copolymer brought to equilibrium in the presence of a B-compatible solvent generally swells or transforms into an A-dispersed (cylindrical or micellar) morphology, depending on solvent content. If the A blocks of the copolymer are glassy, they serve as physical cross-links and stabilize a gel network in which A microdomains are linked through a combination of connected B bridges and entangled B loops. An alternate route by which to introduce solvent into a triblock copolymer, as well as retain the local molecular anisotropy (and bridge population) of the initial lamellar morphology, is to selectively swell the B block and, at sufficiently high solvent concentrations, produce a mesogel. In this work, we describe the formation of mesogels from two chemically related triblock copolymers and employ dynamic mechanical analysis and transmission electron microscopy to examine the features of the resultant nonequilibrium materials.}, number={23}, journal={LANGMUIR}, author={King, MR and White, SA and Smith, SD and Spontak, RJ}, year={1999}, month={Nov}, pages={7886–7889} }
 @article{king_white_smith_spontak_1999, title={Morphology and property development in block copolymer mesogels}, volume={15}, number={1999}, journal={Langmuir}, author={King, M. R. and White, S. A. and Smith, S. D. and Spontak, R.J.}, year={1999}, pages={7886-} }
 @article{laurer_khan_spontak_satkowski_grothaus_smith_lin_1999, title={Morphology and rheology of SIS and SEPS triblock copolymers in the presence of a midblock-selective solvent}, volume={15}, ISSN={["0743-7463"]}, DOI={10.1021/la981441n}, abstractNote={While numerous fundamental studies have sought to elucidate the effect of a parent homopolymer on the morphological characteristics and mechanical properties of microphase-ordered block copolymer blends, few comparable efforts have extended such studies to concentrated copolymer solutions in the presence of a low-molar-mass block-selective solvent. In this work, we investigate the microstructures that form in blends of a poly(styrene-block-isoprene-block-styrene) (SIS) triblock copolymer with a midblock-selective aliphatic mineral oil. To discern the influence of midblock/oil compatibility on blend morphology and properties, identical blends with a poly[styrene-block-(ethylene-alt-propylene)-block-styrene] (SEPS) copolymer, the hydrogenated variant of the SIS copolymer, have likewise been examined. The saturated midblock of the SEPS copolymer is responsible for the observed shifts in morphology stability limits and higher dynamic elastic shear moduli relative to the SIS analogue. These results reveal that...}, number={23}, journal={LANGMUIR}, author={Laurer, JH and Khan, SA and Spontak, RJ and Satkowski, MM and Grothaus, JT and Smith, SD and Lin, JS}, year={1999}, month={Nov}, pages={7947–7955} }
 @article{hong_stolken_zielinski_smith_duda_spontak_1998, title={Anomalous sorption in a poly(styrene-b-isoprene) diblock copolymer near the order-disorder transition}, volume={31}, ISSN={["0024-9297"]}, DOI={10.1021/ma971127k}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTAnomalous Sorption in a Poly(styrene-b-isoprene) Diblock Copolymer near the Order−Disorder TransitionSeong-Uk Hong, Sylvia Stölken, John M. Zielinski, Steven D. Smith, J. Larry Duda, and Richard J. SpontakView Author Information Departments of Materials Science & Engineering and Chemical Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, Institut für Physikalische Chemie, Johannes Gutenberg Universität, 55099 Mainz, Germany, Corporate Research Division, The Procter & Gamble Company, Cincinnati, Ohio 45239, and Departments of Chemical Engineering and Materials Science & Engineering, North Carolina State University, Raleigh, North Carolina 27695 Cite this: Macromolecules 1998, 31, 3, 937–940Publication Date (Web):January 14, 1998Publication History Received28 July 1997Revised13 November 1997Published online14 January 1998Published inissue 1 February 1998https://doi.org/10.1021/ma971127kCopyright © 1998 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views81Altmetric-Citations7LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (54 KB) Get e-AlertsSUBJECTS:Aromatic compounds,Copolymers,Hydrocarbons,Solvents,Sorption Get e-Alerts}, number={3}, journal={MACROMOLECULES}, author={Hong, SU and Stolken, S and Zielinski, JM and Smith, SD and Duda, JL and Spontak, RJ}, year={1998}, month={Feb}, pages={937–940} }
 @article{laurer_hajduk_dreckotter_smith_spontak_1998, title={Bicontinuous morphologies in homologous multiblock copolymers and their homopolymer blends}, volume={31}, ISSN={["0024-9297"]}, DOI={10.1021/ma9807872}, abstractNote={ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTBicontinuous Morphologies in Homologous Multiblock Copolymers and Their Homopolymer BlendsJonathan H. Laurer, Damian A. Hajduk, Stefan Dreckötter, Steven D. Smith, and Richard J. SpontakView Author Information Departments of Materials Science & Engineering and Chemical Engineering, North Carolina State University, Raleigh, North Carolina 27695, Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, and Corporate Research Division, The Procter & Gamble Company, Cincinnati, Ohio 45239 Cite this: Macromolecules 1998, 31, 21, 7546–7549Publication Date (Web):October 2, 1998Publication History Received18 May 1998Revised17 August 1998Published online2 October 1998Published inissue 1 October 1998https://doi.org/10.1021/ma9807872Copyright © 1998 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views229Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (140 KB) Get e-AlertsSUBJECTS:Conformation,Copolymers,Homopolymers,Morphology,X-ray scattering Get e-Alerts}, number={21}, journal={MACROMOLECULES}, author={Laurer, JH and Hajduk, DK and Dreckotter, S and Smith, SD and Spontak, RJ}, year={1998}, month={Oct}, pages={7546–7549} }
 @article{laurer_smith_samseth_mortensen_spontak_1998, title={Interfacial modification as a route to novel bilayered morphologies in binary block copolymer/homopolymer blends}, volume={31}, ISSN={["1520-5835"]}, DOI={10.1021/ma980200j}, abstractNote={Addition of a relatively low-molecular-weight parent homopolymer to a lamellar AB diblock copolymer constitutes a reliable means by which to induce, in controllable fashion, transitions to other morphologies. In this study, we examine the effect of interfacial modification on such transitions in "extended" A(A/B)B copolymer/homopolymer blends in which (i) the A/B midblock fraction (relative to the copolymer molecular weight) is varied from 0.0 to 0.4 in 0.1 increments and (ii) the overall concentration of A ranges from 0.50 to 0.95. As this A/B fraction is increased at constant blend composition, the extent of homopolymer-induced lamellar swelling becomes measurably less pronounced, indicating that the A/B midblock serves to delocalize repulsion along the interphase separating adjacent lamellae. At higher homopolymer concentrations, an increase in the A/B fraction results in the formation of either unilamellar vesicles or a randomly connected bilayered membrane, rather than micelles. These membranes become unstable and transform to micelles at high copolymer dilution. The results presented here are discussed in terms of the complex morphologies observed in, and predicted for, low-molar-mass (co)surfactant systems.}, number={15}, journal={MACROMOLECULES}, author={Laurer, JH and Smith, SD and Samseth, J and Mortensen, K and Spontak, RJ}, year={1998}, month={Jul}, pages={4975–4985} }
 @article{hong_laurer_zielinski_samseth_smith_duda_spontak_1998, title={Morphological and isothermal diffusive probe analyses of low-molecular-weight diblock copolymers}, volume={31}, ISSN={["0024-9297"]}, DOI={10.1021/ma971516e}, abstractNote={While numerous scattering and rheological studies have investigated the disordering mechanism of low-molecular-weight poly(styrene-b-isoprene) (SI) diblock copolymers, relatively few efforts have addressed the real-space morphologies and transport properties of such copolymers at conditions near the order−disorder transition (ODT). In this work, the morphological features of seven compositionally symmetric (50/50 w/w S/I) copolymers ranging in molecular weight from 5000 to 20000, as well as several of their blends, are examined by transmission electron microscopy and small-angle neutron scattering. These results are used to interpret toluene gravimetric sorption data collected at various temperatures. At temperatures above the styrenic glass transition temperature, microphase-ordered copolymer melts are found to exhibit Fickian diffusion. In the case of a copolymer with an experimentally accessible ODT, anomalous sorption (as evidenced by equilibrium overshoot in gravimetric mass-uptake curves) is observe...}, number={7}, journal={MACROMOLECULES}, author={Hong, SU and Laurer, JH and Zielinski, JM and Samseth, J and Smith, SD and Duda, JL and Spontak, RJ}, year={1998}, month={Apr}, pages={2174–2184} }
 @article{norman_kane_white_smith_spontak_1998, title={Triblock copolymer/homopolymer blends: Conformational changes, microstructural transition and macrophase separation}, volume={17}, ISSN={["0261-8028"]}, DOI={10.1023/A:1006565418979}, number={7}, journal={JOURNAL OF MATERIALS SCIENCE LETTERS}, author={Norman, DA and Kane, L and White, SA and Smith, SD and Spontak, RJ}, year={1998}, month={Apr}, pages={545–549} }
 @article{laurer_ashraf_smith_spontak_1997, title={Complex phase behavior of a disordered ''random'' diblock copolymer in the presence of a parent homopolymer}, volume={13}, ISSN={["0743-7463"]}, DOI={10.1021/la960807y}, abstractNote={Previous efforts addressing binary blends of a block copolymer and a parent homopolymer have principally employed ordered copolymers in either the intermediate- or strong-segregation regimes. In this work, blends composed of a disordered (75/25)-b-(50/50) poly[(styrene-r-isoprene)‘-b-(styrene-r-isoprene)‘‘] (S/I)‘-b-(S/I)‘‘ random diblock copolymer (RBC) and homopolystyrene (hS) have been investigated. Blend morphologies, characterized by transmission electron microscopy, are correlated with hS concentration and molecular weight, as well as with changes in the hS Tg, as measured by thermal calorimetry. At low hS fractions (up to 20 wt % hS), the S/I block sequences in the RBC induce competition between attractive and repulsive interactions with hS molecules, resulting in the formation of thin hS channel structures in a continuous RBC matrix. An increase in hS concentration or molecular weight serves to broaden the channels until the morphology resembles macrophase-separated hS domains containing micelle-l...}, number={8}, journal={LANGMUIR}, author={Laurer, JH and Ashraf, A and Smith, SD and Spontak, RJ}, year={1997}, month={Apr}, pages={2250–2258} }
 @article{laurer_fung_sedat_smith_samseth_mortensen_agard_spontak_1997, title={From micelles to randomly connected, bilayered membranes in dilute block copolymer blends}, volume={13}, ISSN={["0743-7463"]}, DOI={10.1021/la9608876}, abstractNote={As macromolecular surfactants, diblock copolymers order into a variety of morphologies in the presence of a parent homopolymer. Here, we probe the effects of chemical incompatibility and interfacial rigidity on the morphology of copolymer/homopolymer blends at constant blend composition. Five copolymers, each possessing a random-sequence midblock that is varied from 0 to 40 wt % of the copolymer molecular weight, have been synthesized for this purpose. While copolymer micelles are representative of dilute (homopolymer-rich) blends, complex bilayered morphologies, including vesicles and the anomalous isotropic `sponge` phase, are produced upon increasing the midblock fraction. Small-angle neutron scattering provides a quantitative assessment of characteristic microstructural dimensions, while transmission electron microtomography yields the first three-dimensional images of the randomly connected, bilayered membrane comprising the sponge phase. 31 refs., 3 figs.}, number={8}, journal={LANGMUIR}, author={Laurer, JH and Fung, JC and Sedat, JW and Smith, SD and Samseth, J and Mortensen, K and Agard, DA and Spontak, RJ}, year={1997}, month={Apr}, pages={2177–2180} }
 @article{laurer_ashraf_smith_samseth_spontak_1997, title={Macromolecular self-assembly in dilute sequence-controlled block copolymer/homopolymer blends}, volume={4}, ISSN={["0968-5677"]}, DOI={10.1016/S0968-5677(96)00048-X}, abstractNote={Conventional block copolymers consist of two long contiguous monomer sequences (‘blocks’) that can, in the same fashion as low-molar-mass surfactants, self-assemble into various microstructural elements (e.g., micelles at low copolymer concentrations) to minimize repulsive contacts in the presence of a parent homopolymer. In this work, we explore the existence of segment-specific interactions, as well as the possibility of tailoring these blend morphologies (and producing altogether new ones), with novel sequence-controlled block copolymers. These copolymers are comprised of at least one block that is a random segment composed of both constituent monomer species. Transmission electron microscopy is employed here to examine the bilayered membranes and channel structures that form in two different series of such copolymers in dilute copolymer/homopolymer blends.}, number={1-2}, journal={SUPRAMOLECULAR SCIENCE}, author={Laurer, JH and Ashraf, A and Smith, SD and Samseth, J and Spontak, RJ}, year={1997}, pages={121–126} }
 @article{laurer_hajduk_fung_sedat_smith_gruner_agard_spontak_1997, title={Microstructural analysis of a cubic bicontinuous morphology in a neat SIS triblock copolymer}, volume={30}, ISSN={["0024-9297"]}, DOI={10.1021/ma970449l}, abstractNote={Department of Materials Science & Engineering, North Carolina State University, Raleigh, North Carolina 27695, Department of Physics, Princeton University, Princeton, New Jersey 08544, Graduate Group in Biophysics, University of California, San Francisco, California 94143, Department of Biochemistry and Biophysics, University of California, San Francisco, California 94143, Corporate Research Division, The Procter & Gamble Company, Cincinnati, Ohio 45239, and Howard Hughes Medical Institute, University of California, San Francisco, California 94143}, number={13}, journal={MACROMOLECULES}, author={Laurer, JH and Hajduk, DA and Fung, JC and Sedat, JW and Smith, SD and Gruner, SM and Agard, DA and Spontak, RJ}, year={1997}, month={Jun}, pages={3938–3941} }
 @article{fung_kane_smith_sedat_agard_spontak_1997, title={Phase behavior of complex diblock copolymer blends: A transmission electron microscopy study}, volume={239-}, ISBN={["0-87849-756-0"]}, ISSN={["0255-5476"]}, DOI={10.4028/www.scientific.net/msf.239-241.179}, journal={PROCEEDINGS OF THE 13TH INTERNATIONAL CONFERENCE ON DEFECTS IN INSULATING MATERIALS - ICDIM 96}, publisher={Utikon-Zurich, Switz.; Enfield, N.H.: Trans Tech Publications}, author={Fung, JC and Kane, L and Smith, SD and Sedat, JW and Agard, DA and Spontak, RJ}, year={1997}, pages={179–184} }
 @article{smith_laurer_ade_smith_ashraf_spontak_1997, title={X-ray microscopy and NEXAFS spectroscopy of macrophase-separated random block copolymer/homopolymer blends}, volume={30}, ISSN={["0024-9297"]}, DOI={10.1021/ma9612687}, abstractNote={Morphological characterization of bulk polymer blends or compatibilized alloys at submicron spatial resolution has almost exclusively relied upon electron microscopy techniques. Since, however, most organic polymers are composed of carbon and light elements, an arsenal of methods to enhance phase contrast has been developed to facilitate discrimination and analysis of propertygoverning morphological features.1 For transmission electron microscopy (TEM), chemical modification of polymeric specimens through, for example, functionality-specific incorporation of heavy-metal staining agents (typically OsO4 or RuO4) may result in ambiguous results due to an inadequate understanding of the staining reaction or competing reaction kinetics. While microanalytical techniques such as light-element energydispersive X-ray mapping2 and electron spectroscopic (energy-filtered) imaging3-5 can potentially eliminate the need for chemical modification in TEM and have proven highly valuable in identifying morphological characteristics in unmodified multiphase polymer systems, they are typically only capable of distinguishing among constituent elements. In addition, appropriate steps must be exercised during data acquisition to minimize specimen damage due to electron beam irradiation. Another microscopy technique recently applied to the morphological characterization of multiphase polymers is X-ray microscopy (XRM),6-9 in which chemical sensitivity is based on the principles of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy.10 This technique utilizes a diffractive optical element (zone plate) to focus highly monochromatic soft X-rays in the energy range of 200-600 eV generated by a synchrotron radiation source onto an ultrathin polymer specimen (typically 100-200 nm in thickness). The transmitted flux is detected as a function of specimen position as the specimen is raster-scanned by piezoelectric transducers. A detailed description of the microscope employed in this work is provided elsewhere.11 The practical spatial resolution of XRM is dictated by zone plate technology, with the smallest available probe presently limited to a full width at half-maximum of about 55 nm, resulting in a minimum feature resolution of about 35 nm. Recent XRM studies of multiphase polymers have successfully elucidated the morphological characteristics of a binary blend composed of polypropylene (PP) and poly(styrene-r-acrylonitrile) (SAN).6,8 Such blends are expected a priori to be highly demixed due to the chemical dissimilarity of the constituent polymers. Moreover, SAN (unlike PP) contains nitrogen, in which case the SAN spatial distribution can be discerned by either XRM or the element-specific techniques mentioned earlier. In this work, we explore the sensitivity of XRM by examining a polymer blend in which the constituent materials are identical in terms of the elements present (C and H only) and, moreover, differ only in terms of their fraction of the same chemical moiety (polystyrene, PS). As a consequence, blends of this type have been found12,13 to exhibit complex phase behavior that is highly dependent on both blend composition and molecular weight considerations. Results obtained here from XRM are compared with TEM micrographs of the same blend after functionalityspecific OsO4 staining. The polymers employed in this work were PS with Mh n ) 120 000 andMh w/Mh n≈ 1.04 and a “random” diblock copolymer (RBC) synthesized by living anionic polymerization in the presence of sec-butyllithium and a potassium alkoxide. A detailed description of the copolymer synthesis and molecular characterization (in terms of monomer sequencing) is provided elsewhere14-16 and is not addressed, for the sake of brevity, in this communication. The RBC was a poly[(styrene-r-isoprene)′-b-(styrene-r-isoprene)′′], (S/I)′-b-(S/I)′′, copolymer, where the ′ and ′′ denote different block compositions, namely, 75/25 and 50/50 (wt %) S/I. The overall composition of the RBC was 68 wt % S, as measured by 1H NMR, and the block lengths were approximately 40 000 each. Two RBC/PS blends, one consisting of 20 wt % RBC and 80 wt % PS and the other 80 wt % RBC and 20 wt % PS, were prepared by solution casting from toluene, as described elsewhere.13 Upon slow solvent evaporation and subsequent annealing, the resultant films were sectioned in a Reichert-Jung Ultracut-S cryoultramicrotome maintained at -100 °C. Sections for TEM analysis, nominally 100-120 nm in thickness and stained with the vapor of OsO4(aq) for 90 min, were imaged on a Zeiss EM902 electron spectroscopic microscope operated at 80 kV and ∆E ) 50 eV. The XRM analysis was performed on the X-1A Beamline of the National Synchrotron Light Source at Brookhaven National Laboratory.}, number={3}, journal={MACROMOLECULES}, author={Smith, AP and Laurer, JH and Ade, HW and Smith, SD and Ashraf, A and Spontak, RJ}, year={1997}, month={Feb}, pages={663–666} }