Search Results - "Roth, Connie B"

Two simultaneous mechanisms causing glass transition temperature reductions in high molecular weight freestanding polymer films as measured by transmission ellipsometry by Pye, Justin E, Roth, Connie B

“…We study the glass transition in confined polymer films and present the first experimental evidence indicating that two separate mechanisms can act…”
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Optimizing the Grafting Density of Tethered Chains to Alter the Local Glass Transition Temperature of Polystyrene near Silica Substrates: The Advantage of Mushrooms over Brushes by Huang, Xinru, Roth, Connie B

“…We measured the local glass transition temperature T g(z) of polystyrene (PS) as a function of distance z from a silica substrate with end-grafted chains using…”
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Physical Aging of Polymer Films Quenched and Measured Free-Standing via Ellipsometry: Controlling Stress Imparted by Thermal Expansion Mismatch between Film and Support by Pye, Justin E, Roth, Connie B

“…We have developed an ellipsometry method to measure the physical aging rate of polymer films that have been thermally quenched and aged in a free-standing…”
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Physical Aging in Ultrathin Polystyrene Films: Evidence of a Gradient in Dynamics at the Free Surface and Its Connection to the Glass Transition Temperature Reductions by Pye, Justin E, Rohald, Kate A, Baker, Elizabeth A, Roth, Connie B

“…We have measured the temperature dependence of the physical aging rate β of thick (2430 nm) and thin (29 nm) polystyrene (PS) films supported on silicon using…”
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Glass transition and chain mobility in thin polymer films by Roth, Connie B., Dutcher, John R.

“…We review recent work on the motion of polymer molecules confined to thin films. There has been considerable experimental evidence for large reductions in the…”
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Eliminating the Enhanced Mobility at the Free Surface of Polystyrene:  Fluorescence Studies of the Glass Transition Temperature in Thin Bilayer Films of Immiscible Polymers by Roth, Connie B, McNerny, Katie L, Jager, Wolter F, Torkelson, John M

“…By selective placement of fluorescent dyes, we have measured the glass transition temperature (T g) of individual layers within supported bilayer films of…”
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Effect of nanoscale confinement on the glass transition temperature of free-standing polymer films: Novel, self-referencing fluorescence method by Kim, Soyoung, Roth, Connie B, Torkelson, John M

“…The effect of nanoscale confinement on the glass transition temperature, Tg, of freely standing polystyrene (PS) films was determined using the temperature…”
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Forming denser glasses on soft substrates by Roth, Connie B.

“…Physical vapour deposition of small-molecule glass formers onto soft substrates enhances the local dynamics at the top free surface, leading to the formation…”
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Comparison of Critical Micelle Concentrations of Gradient Copolymer and Block Copolymer in Homopolymer:  Novel Characterization by Intrinsic Fluorescence by Wong, Christopher L. H, Kim, Jungki, Roth, Connie B, Torkelson, John M

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Development of broad modulus profile upon polymer-polymer interface formation between immiscible glassy-rubbery domains by Gagnon, Yannic J, Burton, Justin C, Roth, Connie B

“…Interfaces of glassy materials such as thin films, blends, and composites create strong unidirectional gradients to the local heterogeneous dynamics that can…”
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Local Glass Transition Temperature T g(z) Within Polystyrene Is Strongly Impacted by the Modulus of the Neighboring PDMS Domain by Gagnon, Yannic J, Roth, Connie B

“…Profiles in the local glass transition temperature T g(z) within polystyrene (PS) next to polydimethylsiloxane (PDMS) domains were determined using a localized…”
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End-Tethered Chains Increase the Local Glass Transition Temperature of Matrix Chains by 45 K Next to Solid Substrates Independent of Chain Length by Merrill, James H., Li, Ruoyu, Roth, Connie B.

“…The local glass transition temperature T g of pyrene-labeled polystyrene (PS) chains intermixed with end-tethered PS chains grafted to a neutral silica…”
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Unexpected Molecular Weight Dependence to the Physical Aging of Thin Polystyrene Films Present at Ultra‐High Molecular Weights by Thees, Michael F., Roth, Connie B.

“…ABSTRACT The physical aging behavior, time‐dependent densification, of thin polystyrene (PS) films supported on silicon are investigated using ellipsometry for…”
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Above, below, and in-between the two glass transitions of ultrathin free-standing polystyrene films: Thermal expansion coefficient and physical aging by Pye, Justin E., Roth, Connie B.

“…ABSTRACT In previous work we observed two simultaneous transitions in high molecular weight (MW) free‐standing polystyrene films that were interpreted as two…”
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Jumping In and Out of the Phase Diagram Using Electric Fields: Time Scale for Remixing of Polystyrene/Poly(vinyl methyl ether) Blends by Kriisa, Annika, Roth, Connie B

“…We demonstrate it is possible to repeatedly jump polystyrene (PS)/poly­(vinyl methyl ether) (PVME) blends from the one-phase to two-phase region by simply…”
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Local Glass Transition Temperature Tg(z) Profile in Polystyrene next to Polybutadiene with and without Plasticization Effects by Kasavan, Benjamin L., Baglay, Roman R., Roth, Connie B.

“…Rubber toughening of glassy polystyrene (PS) has been manufactured commercially for decades as high impact polystyrene, where rubbery poly‐butadiene (PB)…”
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Local Glass Transition Temperature Tg(z) Within Polystyrene Is Strongly Impacted by the Modulus of the Neighboring PDMS Domain by Gagnon, Yannic J, Roth, Connie B

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Selectively Probing the Glass Transition Temperature in Multilayer Polymer Films:  Equivalence of Block Copolymers and Multilayer Films of Different Homopolymers by Roth, Connie B., Torkelson, John M.

“…The temperature dependence of the fluorescence of trace levels of pyrene was employed to measure the glass transition temperatures (T gs) of polystyrene (PS)…”
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Experimental Study of the Influence of Periodic Boundary Conditions: Effects of Finite Size and Faster Cooling Rates on Dissimilar Polymer–Polymer Interfaces by Baglay, Roman R, Roth, Connie B

“…Building on our recent work that mapped the profile in local glass transition temperature T g(z) across a single polystyrene (PS)/poly­(n-butyl methacrylate)…”
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Role of neighboring domains in determining the magnitude and direction of T g -confinement effects in binary, immiscible polymer systems by Evans, Christopher M, Kim, Soyoung, Roth, Connie B, Priestley, Rodney D, Broadbelt, Linda J, Torkelson, John M

“…The glass transition temperature (T g) of a polystyrene (PS) nanolayer is shown to be strongly tuned by the presence of neighboring immiscible polymer layers…”
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