Genix, Anne-Caroline; Bocharova, Vera; Carroll, Bobby; Lehmann, Michelle; Saito, Tomonori; Krueger, Susan; He, Lilin; Dieudonné-George, Philippe; Sokolov, Alexei P.; Oberdisse, Julian
Understanding the Static Interfacial Polymer Layer by Exploring the Dispersion States of Nanocomposites
The dynamic and static properties of the interfacial region between polymer and nanoparticles have wide-ranging consequences on performances of nanomaterials. The thickness and density of the static layer are particularly difficult to assess experimentally due to superimposing nanoparticle interactions. Here, we tune the dispersion of silica nanoparticles in nanocomposites by…
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…
Aggregation behavior of the amyloid model peptide NACore
Pallbo, Jon; Sparr, Emma; Olsson, Ulf
The aggregation of the 11 residue long NACore peptide segment of ?-synuclein (68-GAVVTGVTAVA-78) has been investigated using a combination of cryogenic transmission electron microscopy (cryo-TEM), small- and wide-angle X-ray scattering, and spectroscopy techniques. The aqueous peptide solubility is pH dependent, and aggregation was triggered by a pH quench from pH…
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…
Twisted Ribbon Aggregates in a Model Peptide System
Rüter, Axel; Kuczera, Stefan; Pochan, Darrin J.; Olsson, Ulf
The model peptides A8K and A10K self-assemble in water into ca. 100 nm long ribbon-like aggregates. These structures can be described as ?-sheets laminated into a ribbon structure with a constant elliptical cross-section of 4 by 8 nm, where the longer axis corresponds to a finite number, N ? 15,…
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…
Reinforcement of polychloroprene by grafted silica nanoparticles
Abbas, Zaid M.; Tawfilas, Massimo; Khani, Mohammed M.; Golian, Karl; Marsh, Zachary M.; Jhalaria, Mayank; Simonutti, Roberto; Stefik, Morgan; Kumar, Sanat K.; Benicewicz, Brian C.
Reversible addition-fragmentation chain transfer polymerization of chloroprene on the surface of silica nanoparticles was performed to obtain polychloroprene-grafted-silica nanoparticles (PCP-g-SiO2 NPs). These particles were dispersed in a commercial polychloroprene matrix to obtain PCP nanocomposites with different silica core loadings (1, 5, 10, and 25?wt%). Two different chain graft densities
CO2 capture using three-dimensionally ordered micromesoporous carbon
Vorokhta, Maryna; Morávková, Jaroslava; ?imná?ová, Daniela; Pila?, Radim; Zhigunov, Alexander; vábová, Martina; Sazama, Petr
Adsorption of CO2 on three-dimensionally ordered micromesoporous carbon with a spherical pore structure has been studied using gravimetric and manometric analyses. Adsorptive properties were compared with activated carbon and nanostructured carbon materials such as carbon nanotubes, zeolitic-imidazolate framework-derived carbon, carbon nanohorns and ordered mesoporous carbon materials. The
Unraveling the high strain-rate dynamic stiffening in select model polyurethanes – the role of intermolecular hydrogen bonding
Wu, You-Chi Mason; Hu, Weiguo; Sun, Yuchen; Veysset, David; Kooi, Steven E.; Nelson, Keith A.; Swager, Timothy M.; Hsieh, Alex J.
This study elucidates the influence of molecular attributes on the observed dynamic stiffening in select two-component polyurethanes upon high strain-rate impact. Unlike typical segmented elastomers, polyurethanes consisting of poly(tetramethylene oxide), PTMO, and a diisocyanate, but without a chain extender, are investigated. The hexamethylenediisocyanate (HDI)-based polyurethane, HDI?PU,
Shape and Phase Transitions in a PEGylated Phospholipid System
Viitala, Lauri; Pajari, Saija; Gentile, Luigi; Määttä, Jukka; Gubitosi, Marta; Deska, Jan; Sammalkorpi, Maria; Olsson, Ulf; Murtomäki, Lasse
Poly(ethylene glycol) (PEG) polymers and PEG-conjugated lipids are widely used in bioengineering and drug transport applications. A PEG layer in a drug carrier increases hydrophilic repulsion, inhibits membrane fusion and serum opsonin interactions, and prolongs the storage and circulation time. It can also change the carrier shape and have an…