Yavitt, Benjamin M.; Fei, Hua-Feng; Kopanati, Gayathri N.; Winter, H. Henning; Watkins, James J.
Power Law Relaxations in Lamellae Forming Brush Block Copolymers with Asymmetric Molecular Shape
We report the linear viscoelasticity of densely grafted poly(styrene)-block-poly(ethylene oxide) (PS-b-PEO) diblock bottlebrush block copolymers (dbBB) of equal mass fraction over a wide range of backbone degree of polymerization (Nbb = 21119). The difference in side chain length (PS Mn = 2.9 kg/mol, PEO Mn = 5 kg/mol) produces an…
Gas separation properties of polybenzimidazole/thermally-rearranged polymer blends
Moon, Joshua D.; Bridge, Alexander T.; D’Ambra, Colton; Freeman, Benny D.; Paul, Donald R.
Polybenzimidazole (PBI) is highly selective for H2 removal from mixtures with CO2, but it exhibits low gas permeabilities. Celazole® PBI was blended with more permeable HAB-6FDA-CI, an ortho-functional thermally rearrangeable polyimide, to improve its gas permeabilities while attempting to maintain high selectivity. A compatibilizer, 1-methylimidazole, enhanced phase dispersion when added…
Gradient supramolecular interactions and tunable mechanics in polychaete jaw inspired semi-interpenetrating networks
Thompson, Chase B.; Chatterjee, Sourav; Korley, LaShanda T. J.
Polychaete worms display a remarkable jaw structure, where a gradient in metal-ligand coordination down the length of the jaw results in a shift from hard to soft mechanics. To mimic these gradient structures, a Zn-coordinated supramolecular polymer is crosslinked into a covalent matrix to afford supramolecular semi-interpenetrating networks (SIPNs). These…
Mechanism of stress induced crystallization of polyethylene
Yakovlev, Sergey; Fiscus, David; Brant, Pat; Butler, Jeff; Bucknall, David G.; Downing, Kenneth H.
When polymer melt is subjected to stress, molecular chains become aligned along the elongation direction. However, when polyethylene film crystallizes under stress, molecular chains frequently align perpendicular to the elongation direction. In this paper we investigate why this happens. Evaluating metallocene LLDPE film we show that under the stress lamellae…
Pressure-Driven Solvent Transport and Complex Ion Permeation through Graphene Oxide Membranes
Wang, Kai; Ausri, Irfani R.; Chu, Kyle A.; Seddon, Annela; Tang, Xiaowu (Shirley)
In this paper, an in-depth investigation of three graphene oxide (GO) based membranespure GO, Al3+ intercalated GO (Al-GO), and poly(ethylene glycol) (PEG) modified GO (PEG-GO)is presented. Both Al-GO and PEG-GO membranes have wider interlayer d-spacing compared to pure GO, and the d-spacing size correlates well to the cross-membrane water flux…
Nafion/Protic Ionic Liquid Blends: Nanoscale Organization and Transport Properties
Danyliv, Olesia; Martinelli, Anna
In this work, the possibility of using the protic ionic liquids N-ethylimidazolium trifluoromethylsulfonate, , and N-ethylimidazolium bis(trifluoromethylsulfonyl)imide, , as charge carriers in appropriately modified Nafion membranes has been investigated. The superior thermal stability of ionic liquids, as compared to that of water-based electrolytes, hypothetically offers a
Widely tunable persistent micelle templates via homopolymer swelling
Sarkar, Amrita; Thyagarajan, Akshay; Cole, August; Stefik, Morgan
The combination of precision control with wide tunability remains a challenge for the fabrication of porous nanomaterials suitable for studies of nanostructurebehavior relationships. Polymer micelle templates broadly enable porous materials, however micelle equilibration hampers independent pore and wall size control. Persistent micelle templates (PMT) have emerged as a kinetic controlled
Self-assembly of oppositely charged polyelectrolyte block copolymers containing short thermoresponsive blocks
Hees, I. A. van; Swinkels, P. J. M.; Fokkink, R. G.; Velders, A. H.; Voets, I. K.; Gucht, J. van der; Kamperman, M.
The assembly of oppositely charged block copolymers, containing small thermoresponsive moieties, was investigated as a function of salt concentration and temperature. Aqueous solutions of poly--b-poly (NIPAM44-b-DMAEMA216) and PNIPAM-b-poly-b-PNIPAM (NIPAM35-b-AA200-b-NIPAM35) were mixed in equal charge stoichiometry, and
Preparation of cellulose nanofibers from Miscanthus x. Giganteus by ammonium persulfate oxidation
Yang, Han; Zhang, Yefei; Kato, Ryo; Rowan, Stuart J.
Carboxylic acid functionalized cellulose nanofibers (MxG-CNFA-CO2H) were successfully isolated from a sustainable grass hybrid Miscanthus x. Giganteus by a new two-step chemical oxidation, that involves bleach treatment and ammonium persulfate oxidation, followed by ultrasonication. The resulting MxG-CNFA-CO2Hs have ca. 1200?mmol/kg carboxylic acid surface groups, an aspect ratio of 230 (height
Investigation of Micromechanical Behavior and Voiding of Polyethylene Terephthalate/Polyethylene-stat-methyl Acrylate Blends during Tensile Deformation
Lee, Bongjoon; Onbulak, Sebla; Xu, Yuewen; Topolkaraev, Vasily; McEneany, Ryan; Bates, Frank; Hillmyer, Marc
Micromechanical deformation of polyethylene terephthalate (PET)/ethylene-stat-methyl acrylate copolymer blends was investigated for various MA contents and molar masses of p(E-s-MA). The copolymers were synthesized by ring-opening metathesis polymerization and subsequent hydrogenation. Varying the MA content and molar mass of the copolymer alters the interfacial adhesion between the