Supramolecular polyurea hydrogels with anti-swelling capacity, reversible thermochromic properties, and tunable water content and mechanical performance

Polymer ◽  
2021 ◽  
pp. 124213
Author(s):  
Chengyu Wang ◽  
Yanlong Luo ◽  
Xuzhi Cao ◽  
Bengang Li ◽  
Zhenyang Luo
Keyword(s):  
Water Content ◽  
Mechanical Performance ◽  
Swelling Capacity ◽  
Thermochromic Properties

scholarly journals The Effect of Various Si/Al, Na/Al Molar Ratios and Free Water on Micromorphology and Macro-Strength of Metakaolin-Based Geopolymer

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3845
Author(s):  
Hongguang Wang ◽  
Hao Wu ◽  
Zhiqiang Xing ◽  
Rui Wang ◽  
Shoushuai Dai
Keyword(s):  
Water Content ◽  
Mechanical Performance ◽  
Free Water ◽  
Raw Material ◽  
Current Work ◽  
Molar Ratio ◽  
Composition Analysis ◽  
Structural Water ◽  
Volume Stability ◽  
Molar Ratios

The current work aimed to explore the effect of Na/Al ratios of 0.43, 0.53, 0.63, 0.73, 0.83, and 0.93, using NaOH to alter the molar ratio, on the mechanical properties of a geopolymer material, with fixing of the Si/Al molar ratio. While fixing the Na/Al molar ratio, alteration of the Si/Al ratios to 1.7, 1.75, 1.8, 1.85, 1.9, 1.95 was used, with silica fume and sodium silicate as a silica corrector. The influence on the micromorphology and macro-strength of samples was characterized through SEM, EDS, and compressive strength characterization methods. The results show that Si/Al and Na/Al molar ratios play a significant role in the microstructure and mechanical behavior of MK-based geopolymers, and revealed that the optimal molar Si/Al and Na/Al ratios for attaining maximum mechanical strength in geopolymers are 1.9 and 0.73, respectively. Under various Si/Al ratios, the macro-strength of the geopolymer mainly relies on the formation of NASH gel, rather than zeolites or silicate derivatives. The appropriate Na/Al molar ratio can contribute to the geopolymerization, but a ultra-high Na/Al molar ratio caused a high alkali state that destroyed the microstructure of the geopolymers. Regardless of the amount of water contained in the initial geopolymer raw material, the water content of Si/Al = 1.65 and Si/Al = 1.75 after curing for 10 days was almost the same, and the bound water content of the final geopolymer was maintained at about 15%. Structural water exists in geological polymer gels in the form of a chemical structure. It has effects on the structural performance strength, while free water affects the volume stability of the geological polymer. Overall, the current work provides a perspective on the elemental composition analysis, combined with the molecular structure and micromorphology, to explore the mechanical performance of geopolymers.

State of a Bentonite Barrier after 8 Years of Heating and Hydration in the Laboratory

2006 ◽  
Vol 985 ◽  
Author(s):  
Maria Victoria Villar ◽  
Ana María Fernández ◽  
Roberto Gómez ◽  
José F. Barrenechea ◽  
F. Javier Luque ◽  
...  
Keyword(s):  
Laboratory Test ◽  
Specific Surface ◽  
Water Content ◽  
Surface Area ◽  
Specific Surface Area ◽  
Water Intake ◽  
Bottom Surface ◽  
Dry Density ◽  
Total Length ◽  
Swelling Capacity

AbstractThe conditions of the bentonite in an engineered barrier for HLW disposal have been simulated in a laboratory test. Six cylindrical blocks of bentonite compacted at a dry density of 1.64 g/cm3 were piled up in a hermetic Teflon cell. The total length of clay inside the cell was 60 cm. The bottom surface of the bentonite was heated at 100°C while the top surface was injected with granitic water. The duration of the test was 7.6 years. The water intake was measured during the test and, at the end, the cell was dismounted and the dry density, water content, specific surface area, mineralogy, geochemistry and swelling capacity of the clay were measured in different sections along the blocks. The material used in this test is the FEBEX bentonite.

scholarly journals Mechanically Robust Hydrophobized Double Network Hydrogels for Water Purification

2021 ◽  
Author(s):  
Marshall Allen ◽  
Rahul Sujanani ◽  
Alyssa Chamseddine ◽  
Benny Freeman ◽  
Zachariah Page
Keyword(s):  
Water Content ◽  
Water Purification ◽  
Mechanical Performance ◽  
Polymer Networks ◽  
Ethyl Acrylate ◽  
Salt Transport ◽  
Content Increase ◽  
Free Standing ◽  
Double Network ◽  
Support Materials

Water swollen polymer networks are attractive for applications ranging from tissue regeneration to water purification. For water purification, charged polymers provide excellent ion separation properties. However, many ion exchange membranes (IEMs) are brittle, necessitating the use of thick support materials that ultimately decrease throughput. To this end, a series of double network hydrogels (DNHs), synthesized with varied composition to decrease water content, are examined as robust membrane materials for water purification. One network contains fixed anionic charges, while the other comprises a copolymer with different ratios of hydrophobic ethyl acrylate (EA) and hydrophilic dimethyl acrylamide (DMA) repeat units. Characterizing water content and mechanical performance in free standing DNH films reveals a ~5× decrease in water content, while increasing ultimate stress and strain by ~3.5× and ~4.5× for 90:5 EA:DMA relative to pure DMA. Salt transport properties relevant to water purification, including permeability, solubility, and diffusivity, are measured and show improved performance upon reducing water content. Overall, the ability to simultaneously reduce water content, increase mechanical integrity, and decrease salt transport rates highlights the potential of DNHs for membrane applications.

scholarly journals Mechanically Robust Hydrophobized Double Network Hydrogels for Water Purification

2021 ◽  
Author(s):  
Marshall Allen ◽  
Rahul Sujanani ◽  
Alyssa Chamseddine ◽  
Benny Freeman ◽  
Zachariah Page
Keyword(s):  
Water Content ◽  
Water Purification ◽  
Mechanical Performance ◽  
Polymer Networks ◽  
Ethyl Acrylate ◽  
Salt Transport ◽  
Content Increase ◽  
Free Standing ◽  
Double Network ◽  
Support Materials

Water swollen polymer networks are attractive for applications ranging from tissue regeneration to water purification. For water purification, charged polymers provide excellent ion separation properties. However, many ion exchange membranes (IEMs) are brittle, necessitating the use of thick support materials that ultimately decrease throughput. To this end, a series of double network hydrogels (DNHs), synthesized with varied composition to decrease water content, are examined as robust membrane materials for water purification. One network contains fixed anionic charges, while the other comprises a copolymer with different ratios of hydrophobic ethyl acrylate (EA) and hydrophilic dimethyl acrylamide (DMA) repeat units. Characterizing water content and mechanical performance in free standing DNH films reveals a ~5× decrease in water content, while increasing ultimate stress and strain by ~3.5× and ~4.5× for 90:5 EA:DMA relative to pure DMA. Salt transport properties relevant to water purification, including permeability, solubility, and diffusivity, are measured and show improved performance upon reducing water content. Overall, the ability to simultaneously reduce water content, increase mechanical integrity, and decrease salt transport rates highlights the potential of DNHs for membrane applications.

Characterization of frozen hydrated biological specimens by low-loss EELS

1992 ◽  
Vol 50 (2) ◽  
pp. 1572-1573
Author(s):  
Songquan Sun ◽  
Richard D. Leapman
Keyword(s):  
Water Content ◽  
Direct Method ◽  
Internal Standard ◽  
Dry Weight ◽  
Dark Field ◽  
Protein Solutions ◽  
Subcellular Compartment ◽  
Differential Shrinkage ◽  
Electron Energy Loss

Analyses of ultrathin cryosections are generally performed after freeze-drying because the presence of water renders the specimens highly susceptible to radiation damage. The water content of a subcellular compartment is an important quantity that must be known, for example, to convert the dry weight concentrations of ions to the physiologically more relevant molar concentrations. Water content can be determined indirectly from dark-field mass measurements provided that there is no differential shrinkage between compartments and that there exists a suitable internal standard. The potential advantage of a more direct method for measuring water has led us to explore the use of electron energy loss spectroscopy (EELS) for characterizing biological specimens in their frozen hydrated state.We have obtained preliminary EELS measurements from pure amorphous ice and from cryosectioned frozen protein solutions. The specimens were cryotransfered into a VG-HB501 field-emission STEM equipped with a 666 Gatan parallel-detection spectrometer and analyzed at approximately −160 C.

STEM measurement of subcellular water distributions

1993 ◽  
Vol 51 ◽  
pp. 568-569
Author(s):  
R.D. Leapman ◽  
S.Q. Sun ◽  
S-L. Shi ◽  
R.A. Buchanan ◽  
S.B. Andrews
Keyword(s):  
Water Content ◽  
Internal Standard ◽  
Dry Weight ◽  
Dry Mass ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Bulk Water ◽  
Inelastic Electron ◽  
Scanning Transmission ◽  
Annular Dark Field

Recent advances in rapid-freezing and cryosectioning techniques coupled with use of the quantitative signals available in the scanning transmission electron microscope (STEM) can provide us with new methods for determining the water distributions of subcellular compartments. The water content is an important physiological quantity that reflects how fluid and electrolytes are regulated in the cell; it is also required to convert dry weight concentrations of ions obtained from x-ray microanalysis into the more relevant molar ionic concentrations. Here we compare the information about water concentrations from both elastic (annular dark-field) and inelastic (electron energy loss) scattering measurements.In order to utilize the elastic signal it is first necessary to increase contrast by removing the water from the cryosection. After dehydration the tissue can be digitally imaged under low-dose conditions, in the same way that STEM mass mapping of macromolecules is performed. The resulting pixel intensities are then converted into dry mass fractions by using an internal standard, e.g., the mean intensity of the whole image may be taken as representative of the bulk water content of the tissue.

Sign in / Sign up

Export Citation Format

Share Document