Miranda, Daniel F.; Zhang, Shihai; Runt, James
Controlling Crystal Microstructure To Minimize Loss in Polymer Dielectrics
A model semicrystalline polymer, poly(ethylene naphthalate) (PEN), was used to examine how morphological factors inhibit chain segment relaxations that contribute to dielectric loss. This was achieved by manipulating the extent of crystallization and the crystalline microstructure through a combination of annealing and uniaxial drawing and investigating the effects on dielectric…
Structural transformation from shish-kebab crystals to micro-fibrils through hot stretching process of gel-spun ultra-high molecular weight polyethylene fibers with high concentration solution
An, Minfang; Lv, You; Yao, Guibin; Zhang, Li; Wang, Zongbao
Structural evolution of gel-spun ultra-high molecular weight polyethylene fibers with high concentration solution via hot stretching process was investigated by in situ small-angle X-ray scattering, in situ wide-angle X-ray diffraction measurements, scanning electron microscopy, and differential scanning calorimetry. With the increase of stretching strain, the long period continuously increases…
Generating Nanoscopic Patterns in Conductivity within a Poly(3-hexylthiophene) Crystal via Bias-Controlled Scanning Probe Nanolithography
Wang, Binghua; Zhang, Bin; Shen, Changyu; Chen, Jingbo; Reiter, Günter
Generating Nanoscopic Patterns in Conductivity within a Poly(3-hexylthiophene) Crystal via Bias-Controlled Scanning Probe…
Cavitation in Poly(4-methyl-1-pentene) during Tensile Deformation
Chen, Ran; Lu, Ying; Jiang, Zhiyong; Men, Yongfeng
The poly(4-methyl-1-pentene) sample was used to investigate the cavitation-induced stress-whitening phenomenon during stretching at different temperatures via the ultrasmall-angle X-ray scattering technique. Two modes of cavitation were found that mode I cavitation activated around yield point followed by mode II cavitation generated in highly oriented state. The critical strain for…
Characterization of multi-scale structure and thermal properties of Indica rice starch with different amylose contents
Li, Zhihang; Kong, Xiangli; Zhou, Xianrong; Zhong, Kui; Zhou, Sumei; Liu, Xingxun
Fully understanding the relationship between multi-scale structure and thermal properties of rice starch is important for starch-based food processing. Multi-scale structures of Indica rice starch were studied from molecules to aggregation structure. Gel-permeation chromatography (GPC) and high-performance anion-exchange chromatography (HPAEC) both show that the amylopectin from debranched rice…
Ordered Mesoporous to Macroporous Oxides with Tunable Isomorphic Architectures: Solution Criteria for Persistent Micelle Templates
Lokupitiya, Hasala N.; Jones, Alexis; Reid, Barry; Guldin, Stefan; Stefik, Morgan
Porous and nanoscale architectures of inorganic materials have become crucial for a range of energy and catalysis applications, where the ability to control the morphology largely determines the transport characteristics and device performance. Despite the availability of a range of block copolymer self-assembly methods, the conditions for tuning the key…
Bandgap-Tuning in Triple-Chalcogenophene Polymer Films by Thermal Annealing
González, Daniel Moseguí; Raftopoulos, Konstantinos N.; He, Gang; Papadakis, Christine M.; Brown, Alex; Rivard, Eric; Müller-Buschbaum, Peter
Macromolecular Rapid Communications, 2017, DOI:Visit the full articleBack to the overview
Blocked Shape Memory Effect in Negative Poisson’s Ratio Polymer Metamaterials
Boba, Katarzyna; Bianchi, Matteo; McCombe, Greg; Gatt, Ruben; Griffin, Anselm C.; Richardson, Robert M.; Scarpa, Fabrizio; Hamerton, Ian; Grima, Joseph N.
We describe a new class of negative Poisson’s ratio (NPR) open cell PU–PE foams produced by blocking the shape memory effect in the polymer. Contrary to classical NPR open cell thermoset and thermoplastic foams that return to their auxetic phase after reheating (and therefore limit their use in technological applications),…
Polymer-Grafted Nanoparticle Membranes with Controllable Free Volume
Bilchak, Connor R.; Buenning, Eileen; Asai, Makoto; Zhang, Kai; Durning, Christopher J.; Kumar, Sanat K.; Huang, Yucheng; Benicewicz, Brian C.; Gidley, David W.; Cheng, Shiwang; Sokolov, Alexei P.; Minelli, Matteo; Doghieri, Ferruccio
Polymer-based membranes play a key role in several industrially important gas separation technologies, e.g., removing CO2 from natural gas, with enormous economic and environmental impact. Here, we develop a novel hybrid membrane construct comprised entirely of nanoparticles grafted with polymers. These membranes are shown to have broadly tunable separation performance…
Progression of the Morphology in Random Ionomers Containing Bulky Ammonium Counterions
Enokida, Joshua S.; Tanna, Vijesh A.; Winter, H. Henning; Coughlin, E. Bryan
Poly(isoprene-ran-dimethyloctylammonium styrenesulfonate) (P(I-ran-DMOASS)) copolymers with high molecular weights and dimethyloctylammonium styrenesulfonate (DMOASS) compositions ranging between 8 and 40 mol % (30 and 77 wt %) were synthesized via nitroxide-mediated polymerization. Thermal and viscoelastic characterization revealed distinct behaviors for the low (30–51 wt %) and high (56–77 wt…