Publications by authors named "Ryan J Fox"

Article Synopsis
  • The study focuses on the development of nanocomposite films made from a sulfonated, all-aromatic polyamide (PBDT) and graphene oxide (GO) platelets, enhanced through thermal reduction of GO to reduced GO (rGO).
  • The results show improved structural alignment and mechanical properties of the PBDT-rGO films, with significant increases in Young's modulus (from 16 to 37 GPa) and tensile strength (from 210 to 640 MPa) at 1.8 vol % rGO.
  • Techniques like X-ray scattering and dynamic mechanical thermal analysis confirm that the incorporation of rGO enhances local stiffness and alters the interaction energy within the polymer matrix.
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Vestibulodynia (VBD), an idiopathic pain disorder characterized by erythema and pain of the vulvar vestibule (the inner aspect of the labia minora and vaginal opening), is the most common cause of sexual pain for women of reproductive age. Women also feel discomfort with contact with clothing and tampon use. As most women with this disorder only have pain with provocation of the tissue, topical anesthetics applied to the vestibule are the current first line treatment for temporary pain relief.

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We report irreversible, shear-activated gelation in liquid crystalline solutions of a rigid polyelectrolyte that forms rodlike assemblies (rods) in salt-free solution. At rest, the liquid crystalline solutions are kinetically stable against gelation and exhibit low viscosities. Under steady shear at, or above, a critical shear rate, a physically cross-linked, nematic gel network forms due to linear growth and branching of the rods.

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We report on the shear rheology of liquid crystalline solutions composed of charged, rodlike polymers that form supramolecular assemblies dispersed in water. Under steady shear, we observe shear thickening behavior, followed by a hesitation in the viscosity accompanied by an extremely narrow range of negative first normal stress difference. The Peclet number (Pe, shear rate normalized by rod rotational diffusivity) for the onset of shear thickening is in agreement with previous, high-resolution numerical simulations of the Doi-Edwards-Hess kinetic theory.

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Article Synopsis
  • Researchers are exploring the combination of polymers with carbon-based nanofillers like graphene to create lightweight nanocomposites with great mechanical strength.
  • Despite the potential, creating these nanocomposites has been challenging due to issues with filler-polymer compatibility and processing.
  • The study introduces a simple water-based method that mixes two liquid crystalline solutions to produce strong nanocomposite films reinforced with graphene oxide.
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Polymer electrolyte membranes (PEMs) with high volume fractions of ionic liquids (IL) and high modulus show promise for enabling next-generation gas separations, and electrochemical energy storage and conversion applications. Herein, we present a conductive polymer-IL composite based on a sulfonated all-aromatic polyamide (sulfo-aramid, PBDT) and a model IL, which we term a PBDT-IL composite. The polymer forms glassy and high-aspect-ratio hierarchical nanofibrils, which enable fabrication of PEMs with both high volume fractions of IL and high elastic modulus.

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