A novel approach to alginate aerogels: carbon dioxide induced gelation

RSC Advances ◽  
2015 ◽  
Vol 5 (11) ◽  
pp. 7812-7818 ◽  
Author(s):  
P. Gurikov ◽  
S. P. Raman ◽  
D. Weinrich ◽  
M. Fricke ◽  
I. Smirnova
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Drying ◽  
Novel Approach

A novel process, carbon dioxide induced gelation, opens new pathways towards hydrogels and can be coupled with supercritical drying to produce aerogels.

Hierarchically Nanostructured Zeolites of Tunable Porosities with Aerogel Templating

2011 ◽  
Vol 1306 ◽  
Author(s):  
Yousheng Tao ◽  
Morinobu Endo ◽  
Katsumi Kaneko
Keyword(s):  
Carbon Dioxide ◽  
Template Synthesis ◽  
Colloidal Silica ◽  
Lower Cost ◽  
Supercritical Drying ◽  
Nanoporous Carbon ◽  
Carbon Aerogels ◽  
Resorcinol Formaldehyde ◽  
Carbon Xerogels ◽  
Recent Developments

ABSTRACTWe present the synthesis of resorcinol-formaldehyde aerogels and carbon aerogels of different nanoporosities, emphasizing on the recent developments in fabrication pathways of lower cost. Recent results showed a simple way to the production of highly nanoporous carbon xerogels. While using an approach combined colloidal silica nanocasting and carbon dioxide supercritical drying, hydrophilicity-controlled carbon aerogels with high mesoporosity were synthesized. Then, we demonstrate the functions of these aerogels for template synthesis of hierarchically nanostructured zeolites having micropores and mesopores.

scholarly journals Ultralight-Weight Cellulose Aerogels from NBnMO-Stabilized Lyocell Dopes

2007 ◽  
Vol 2007 ◽  
pp. 1-4 ◽  
Author(s):  
Falk Liebner ◽  
Antje Potthast ◽  
Thomas Rosenau ◽  
Emmerich Haimer ◽  
Martin Wendland
Keyword(s):  
Carbon Dioxide ◽  
Solid State ◽  
Solution Structure ◽  
Supercritical Drying ◽  
Regenerated Cellulose ◽  
Cellulose Content ◽  
Solvent Exchange ◽  
New Materials ◽  
Specific Density ◽  
Regeneration Procedure

Cellulose aerogels are intriguing new materials produced by supercritical drying of regenerated cellulose obtained by solvent exchange of solid Lyocell moldings. FromN-methylmorpholine-N-oxide solutions with cellulose contents between 1 and 12%, dimensionally stable cellulose bodies are produced, in which the solution structure of the cellulose is largely preserved and transferred into the solid state. The specific density and surface of the obtained aerogels range from 0.05 to 0.26 g/cm3and from 172 to 284m2/g, respectively, depending on the cellulose content of the Lyocell dopes and regeneration procedure. A reliable extraction and drying procedure using supercritical carbon dioxide, the advantageous use of NBnMO as stabilizer for the Lyocell dopes, and selected physical properties of the materials is communicated.

Creating Nanoporosity by Selective Extraction of Porogens Using Supercritical Carbon Dioxide/Cosolvent Processes

2003 ◽  
Vol 766 ◽  
Author(s):  
B. Lahlouh ◽  
T. Rajagopalan ◽  
J. A. Lubguban ◽  
N. Biswas ◽  
S. Gangopadhyaya ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Selective Extraction ◽  
Organic Polymer ◽  
K Value ◽  
Degradation Temperature ◽  
Novel Approach ◽  
The Matrix ◽  
Closed Pore ◽  
Supercritical Carbon

AbstractThis work presents a novel approach using supercritical carbon dioxide (SCCO2) to selectively extract poly(propylene glycol) (PPG) porogen from a poly(methylsilsesquioxane) (PMSSQ) matrix, which results in the formation of nanopores. Nanoporous thin films were prepared by spin-casting a solution containing appropriate quantities of PPG porogen and PMSSQ dissolved in PM acetate. The as-spun films were thermally cured at temperatures well below the thermal degradation temperature of the organic polymer to form a cross-linked organic/inorganic polymer hybrid. By selectively removing the CO2 soluble PPG porogen, open and closed pore structures are possible depending upon the porogen load and its distribution in the matrix before extraction. In the present work, two different loadings of PPG namely 25 wt.% and 55 wt.% were used. Both static SCCO2 and pulsed SCCO2/cosolvent treatments were used for PPG extraction. The initial results indicate that the pulsed SCCO2/cosolovent treatment was more efficient. Fourier transform infrared spectroscopy (FTIR) and refractive index measurements further corroborate the successful extraction of the porogens at relatively low temperatures (2000C). For the pure PMSSQ film, the k value is 3.1, whereas it is 1.46 and 2.27 for the open and closed pore compositions respectively after the static SCCO2 extraction and 430°C subsequent annealing. The reduction in the k-value is attributed to the formation of nanopores. The pore structure was verified from transmission electron microscopy (TEM), and from small-angle x-ray scattering (SAXS) measurements, the pore size was determined to be 1-3 nm for these films.

Synthesis of Low-Density Microcellular Materials

MRS Bulletin ◽  
1990 ◽  
Vol 15 (12) ◽  
pp. 24-29
Keyword(s):  
Carbon Dioxide ◽  
Surface Tension ◽  
Phase Separation ◽  
Room Temperature ◽  
Supercritical Drying ◽  
Small Cells ◽  
Underlying Structure ◽  
Low Density ◽  
Liquid Meniscus ◽  
Temperature Liquid

This section describes and gives examples of processes developed at the DOE laboratories to make LDMMs. In general, these processes fall under one of two schemes: (1) phase separation of polymer or polymer-like solutions, or (2) replication of sacrificial pore formers. Both schemes produce a liquid-filled precursor. The LDMM can be obtained only if this precursor can be “dried” without collapsing the underlying structure. This key synthetic step is rarely a trivial task, and because of its importance, this section starts with a description of LDMM drying technologies.Most liquid-filled LDMM precursors will collapse into a high-density mass if subjected to evaporative drying. This occurs because large capillary forces are generated when the liquid meniscus moves through the small cells and pores of the precursor. Only very strong and relatively large-celled precursor structures (e.g., inverse emulsions) can withstand these forces.Some LDMM precursors of moderate strength can be dried by evaporation if the precursor is exchanged into a liquid of low surface tension. Liquified carbon dioxide is an example — at room temperature, liquid CO2 has a surface tension of 1–2 dynes/cm, compared to ˜70 dynes/cm for water, and 20–40 dynes/cm for most organic solvents. CO2 evaporative drying should not be confused with C02 supercritical drying discussed later.

Carbon dioxide sensor for mobile devices: A novel approach for low-power consuming, highly sensitive NDIR sensors

2016 ◽  
Author(s):  
Louisa Scholz ◽  
Alvaro Ortiz Perez ◽  
Benedikt Bierer ◽  
Ponkanok Eaksen ◽  
Jurgen Wollenstein ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Low Power ◽  
Mobile Devices ◽  
Novel Approach ◽  
Highly Sensitive ◽  
Carbon Dioxide Sensor

A novel approach to precise evaluation of carbon dioxide flow behaviour in siltstone under tri-axial drained conditions

2016 ◽  
Vol 34 ◽  
pp. 331-340 ◽  
Author(s):  
C.P. Zhang ◽  
P.G. Ranjith ◽  
M.S.A. Perera ◽  
J. Zhao ◽  
Decheng Zhang ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Flow Behaviour ◽  
Precise Evaluation ◽  
Novel Approach
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