scholarly journals Rearranged Copolyurea Networks for Selective Carbon Dioxide Adsorption at Room Temperature

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 4004
Author(s):  
Junsik Nam ◽  
Eunkyung Jeon ◽  
Su-Young Moon ◽  
Ji-Woong Park
Keyword(s):  
Carbon Dioxide ◽  
Chemical Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Sol Gel ◽  
Hexamethylene Diisocyanate ◽  
Carbon Dioxide Adsorption ◽  
Bond Rearrangement ◽  
Polymerization Method ◽  
Adsorption Quantity

Copolyurea networks (co-UNs) were synthesized via crosslinking polymerization of a mixture of tetrakis(4-aminophenyl)methane (TAPM) and melamine with hexamethylene diisocyanate (HDI) using the organic sol-gel polymerization method. The subsequent thermal treatment of between 200 and 400 °C induced the sintering of the powdery polyurea networks to form porous frameworks via urea bond rearrangement and the removal of volatile hexamethylene moieties. Incorporating melamine into the networks resulted in a higher nitrogen content and micropore ratio, whereas the overall porosity decreased with the melamine composition. The rearranged network composed of the tetraamine/melamine units in an 80:20 ratio showed the highest carbon dioxide adsorption quantity at room temperature. The results show that optimizing the chemical structure and porosity of polyurea-based networks can lead to carbon dioxide adsorbents working at elevated temperatures.

Carbon Capture Performance of Amino-Modified MIL-101 at Room Temperature

2013 ◽  
Vol 395-396 ◽  
pp. 637-640
Author(s):  
Yi Yang ◽  
Zheng Ping Wang ◽  
Ling Meng ◽  
Lian Jun Wang
Keyword(s):  
Carbon Dioxide ◽  
Specific Surface ◽  
Pore Structure ◽  
Carbon Capture ◽  
Room Temperature ◽  
Ambient Pressure ◽  
Metal Organic Framework ◽  
Adsorption Properties ◽  
Carbon Dioxide Adsorption ◽  
Before And After

MIL-101, a metal-organic framework material, was synthesized by the high-temperature hydrothermal method. Triethylenetetramine (TETA) modification enabled the effective grafting of an amino group onto the surface of the materials and their pore structure. The crystal structure, micromorphology, specific surface area, and pore structure of the samples before and after modification were analyzed with an X-ray diffractometer, scanning electron microscope, specific surface and aperture tester, and infrared spectrometer. The carbon dioxide adsorption properties of the samples were determined by a thermal analyzer before and after TETA modification. Results show that moderate amino modification can effectively improve the microporous structure of MIL-101 and its carbon dioxide adsorption properties. After modification, the capacity of MIL-101 to adsorb carbon dioxide decreased only by 0.61 wt%, and a high adsorption capacity of 9.45 wt% was maintained after six cycles of adsorption testing at room temperature and ambient pressure.

scholarly journals Drastic Enhancement of Carbon Dioxide Adsorption in Fluoroalkyl-Modified Poly(allylamine)

2021 ◽  
Author(s):  
Athanasios Koutsianos ◽  
Louise B. Hamdy ◽  
Chun-Jae Yoo ◽  
Jason J. Lee ◽  
Marco Taddei ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Bonding ◽  
Room Temperature ◽  
Polymer Chains ◽  
High Polymer ◽  
Carbon Dioxide Adsorption ◽  
Positron Annihilation Lifetime ◽  
Gas Streams ◽  
Amine Hydrogen ◽  
Amine Content

Polyamine-based carbon dioxide sorbents suffer from a seesaw relationship between amine content and amine efficiency. High polyamine loadings equate to increased amine contents, but often at the expense of amine efficiency. Carbon dioxide mass transport in compact polymers is severely limited, especially at ambient temperature. High polymer contents curtail diffusion pathways, hindering CO2 from reaching and reacting with the numerous amine functions. Here, we overcome this issue using poly(allylamine) (PAA) grafted with short fluoroalkyl chains and then cross-linked with C60. As experimentally evidenced by positron annihilation lifetime spectroscopy, the incorporation of fluoroalkyl chains generates free volume elements that act as additional diffusion pathways within the material. The inclusion of void volume in fluoroalkyl-functionalized PAA sorbents results in radically increased CO2 uptakes and amine efficiencies in diluted gas streams at room temperature, including simulated air. We speculate that the hydrophobic fluorinated functions interfere with the strong amine hydrogen bonding network disrupting and consequently altering the packing and conformation of the polymer chains. The evidence presented here is a blueprint for the development of more efficient amine-based CO2 sorbents

Tubular Titanates: Alkali-Metal Ion-Exchange Features and Carbon Dioxide Adsorption at Room Temperature

2019 ◽  
Vol 58 (13) ◽  
pp. 5168-5174 ◽  
Author(s):  
Eri Uematsu ◽  
Atsushi Itadani ◽  
Hideki Hashimoto ◽  
Kazuyoshi Uematsu ◽  
Kenji Toda ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ion Exchange ◽  
Alkali Metal ◽  
Metal Ion ◽  
Room Temperature ◽  
Carbon Dioxide Adsorption ◽  
Alkali Metal Ion ◽  
Metal Ion Exchange

scholarly journals Long term storage of miRNA at room and elevated temperatures in a silica sol–gel matrix

RSC Advances ◽  
2021 ◽  
Vol 11 (50) ◽  
pp. 31505-31510
Author(s):  
Rajat Chauhan ◽  
Theodore S. Kalbfleisch ◽  
Chinmay S. Potnis ◽  
Meenakshi Bansal ◽  
Mark W. Linder ◽  
...  
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Sol Gel ◽  
Silica Sol ◽  
Rapid Degradation ◽  
Global Impact ◽  
Long Term Storage ◽  
Term Storage ◽  
Over Time

Storage of biospecimens in their near native environment at room temperature can have a transformative global impact, however, this remains an arduous challenge to date due to the rapid degradation of biospecimens over time.

Spectroscopic Investigations of Neptunium's and Plutonium's Oxidation States in Sol-Gel Glasses as a Function of Initial Valence and Thermal History

1996 ◽  
Vol 465 ◽  
Author(s):  
N. A. Stump ◽  
R. G. Haire ◽  
S. Dai
Keyword(s):  
Oxidation State ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Sol Gel ◽  
Solidification Process ◽  
Silica Matrix ◽  
Oxidation States ◽  
Temperature Spectra ◽  
Gel Glasses ◽  
Starting Solutions

ABSTRACTSeveral oxidation states of neptunium and plutonium, Pu(III), Pu(IV), Pu(VI), Np(IV), Np(V), and Np(VI), were studied in glasses prepared by a sol-gel technology. The oxidation state of these actinides in the sol-gel product was examined by absorption spectroscopy after solidification, aging, and thermal treatment. The oxidation state of the actinides in the starting solutions was essentially maintained through the solidification process of the silica matrix. However, during densification and removal of residual solvents at elevated temperatures, both actinides converted eventually to their tetra valent states while in the different sol-gel products. This finding is in accord with reports that tetravalent states of plutonium and neptunium are acquired in glass products prepared by dissolution of the actinide in molten glasses. Comparisons between room temperature spectra obtained from neptunium and plutonium in heated sol-gel products and from molten glass products showed subtle differences that can be related to the metal ion's environments.

Proton Conducting Nano Hybrid Membranes Synthesized from Temperature Tolerant Polydimethylsiloxane (PDMS) Polymers

2003 ◽  
Vol 788 ◽  
Author(s):  
Je-Deok Kim ◽  
Itaru Honma
Keyword(s):  
Thermal Stability ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Phosphotungstic Acid ◽  
Sol Gel ◽  
Hybrid Membranes ◽  
Titanium Oxides ◽  
Proton Conducting ◽  
Zirconium Oxides ◽  
Maximum Conductivity

ABSTRACTFlexible and temperature tolerant nano-hybrid membranes consisting of zirconium (titanium) oxides and polydimethysiloxane (PDMS) with the different molecular mass of 4500 and 600 have been synthesized by sol-gel processes. The membrane of zirconium/PDMS=2 (in molar) showed enhanced thermal stability and flexibility up to 300 °C due to the presence of cross-linkable inorganic nano-phase in the hybrid macromolecular matrix. The membrane becomes proton conducting polymer electrolyte when doped with 12-phosphotungstic acid (PWA). The proton conducting properties of the hybrid membranes with various PWA concentration were measured in the temperature range from room temperature to 150°C under saturated humidity conditions. A maximum conductivity of 2×10-2 S/cm was obtained at 150°C when the PDMS/zirconium oxides hybrid matrix was changed to gel state due to the higher water activity at elevated temperatures.

scholarly journals Drastic Enhancement of Carbon Dioxide Adsorption in Fluoroalkyl-Modified Poly(allylamine)

2021 ◽  
Author(s):  
Athanasios Koutsianos ◽  
Louise B. Hamdy ◽  
Chun-Jae Yoo ◽  
Jason J. Lee ◽  
Marco Taddei ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Bonding ◽  
Room Temperature ◽  
Polymer Chains ◽  
High Polymer ◽  
Carbon Dioxide Adsorption ◽  
Positron Annihilation Lifetime ◽  
Gas Streams ◽  
Amine Hydrogen ◽  
Amine Content

Polyamine-based carbon dioxide sorbents suffer from a seesaw relationship between amine content and amine efficiency. High polyamine loadings equate to increased amine contents, but often at the expense of amine efficiency. Carbon dioxide mass transport in compact polymers is severely limited, especially at ambient temperature. High polymer contents curtail diffusion pathways, hindering CO2 from reaching and reacting with the numerous amine functions. Here, we overcome this issue using poly(allylamine) (PAA) grafted with short fluoroalkyl chains and then cross-linked with C60. As experimentally evidenced by positron annihilation lifetime spectroscopy, the incorporation of fluoroalkyl chains generates free volume elements that act as additional diffusion pathways within the material. The inclusion of void volume in fluoroalkyl-functionalized PAA sorbents results in radically increased CO2 uptakes and amine efficiencies in diluted gas streams at room temperature, including simulated air. We speculate that the hydrophobic fluorinated functions interfere with the strong amine hydrogen bonding network disrupting and consequently altering the packing and conformation of the polymer chains. The evidence presented here is a blueprint for the development of more efficient amine-based CO2 sorbents

Mechanical Properties and Dislocation Structure of Single Crystal Cdte Deformed in Compression at 300°C

1976 ◽  
Vol 34 ◽  
pp. 592-593
Author(s):  
Ernest L. Hall ◽  
J. B. Vander Sande
Keyword(s):  
Mechanical Properties ◽  
Single Crystal ◽  
Dislocation Structure ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Strain Curve ◽  
Optical Devices ◽  
Semiconductor Compound ◽  
Wide Range ◽  
Sample Orientation

The present paper describes research on the mechanical properties and related dislocation structure of CdTe, a II-VI semiconductor compound with a wide range of uses in electrical and optical devices. At room temperature CdTe exhibits little plasticity and at the same time relatively low strength and hardness. The mechanical behavior of CdTe was examined at elevated temperatures with the goal of understanding plastic flow in this material and eventually improving the room temperature properties. Several samples of single crystal CdTe of identical size and crystallographic orientation were deformed in compression at 300°C to various levels of total strain. A resolved shear stress vs. compressive glide strain curve (Figure la) was derived from the results of the tests and the knowledge of the sample orientation.

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