Ultralight-Weight Cellulose Aerogels from NBnMO-Stabilized Lyocell Dopes

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.

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Cellulose aerogels: Highly porous, ultra-lightweight materials

Holzforschung ◽

10.1515/hf.2008.051 ◽

2008 ◽

Vol 62 (2) ◽

pp. 129-135 ◽

Cited By ~ 61

Author(s):

Falk Liebner ◽

Antje Potthast ◽

Thomas Rosenau ◽

Emmerich Haimer ◽

Martin Wendland

Keyword(s):

Carbon Dioxide ◽

Solid State ◽

Solution Structure ◽

Supercritical Drying ◽

Regenerated Cellulose ◽

Solvent Exchange ◽

New Materials ◽

Surface Areas ◽

Degradation Reactions ◽

Highly Porous

Abstract Cellulosic aerogels are intriguing new materials produced by supercritical drying of regenerated cellulose obtained by solvent exchange of solid Lyocell moldings. From N-methylmorpholine-N-oxide (NMMO) 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 material having densities down to 0.05 g cm-3 and surface areas of up to 280 m2 g-1. In this study, several aspects of cellulosic aerogel production are communicated: the stabilization of the cellulose solutions against degradation reactions by agents suitable for later extraction and drying, a reliable extraction and drying procedure by supercritical carbon dioxide, the advantages of DMSO/NMMO in this procedure as a solvent/non-solvent pair, and some data on the physical properties of the materials.

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Investigation of Aerogel Production Processes: Solvent Exchange under High Pressure Combined with Supercritical Drying in One Apparatus

Gels ◽

10.3390/gels7010004 ◽

2021 ◽

Vol 7 (1) ◽

pp. 4

Author(s):

Artem Lebedev ◽

Ekaterina Suslova ◽

Aleksander Troyankin ◽

Daria Lovskaya

Keyword(s):

Carbon Dioxide ◽

Phase Diagram ◽

Experimental Study ◽

Supercritical Drying ◽

Solvent Exchange ◽

Efficient Technology ◽

Production Processes ◽

Improve Production Technology ◽

Homogeneous Regions ◽

Organic Aerogels

This work aims to contribute to the theoretical and experimental research of supercritical processes for intensification and combination in one apparatus. Investigation is carried out to improve production technology of organic alginate aerogels. It is proposed within the investigation to carry out the solvent exchange stage, an important stage of organic aerogels production, under pressure in a carbon dioxide medium in the same apparatus used for supercritical drying. The phase behavior in the system “carbon dioxide–water–2-propanol”, which arises during such a solvent exchange stage, is studied theoretically. An experimental study of the process of step-by-step solvent exchange under pressure was carried out through multiphase and homogeneous regions of the phase diagram of such a system. As a result, new highly efficient technology for the production of organic aerogels was proposed, which can be implemented by combining the two main stages of the process.

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Improvement of Solvent Exchange for Supercritical Dried Aerogels

Frontiers in Materials ◽

10.3389/fmats.2021.662487 ◽

2021 ◽

Vol 8 ◽

Author(s):

Marina Schwan ◽

Sarah Nefzger ◽

Behdad Zoghi ◽

Christina Oligschleger ◽

Barbara Milow

Keyword(s):

Carbon Dioxide ◽

Solvent Extraction ◽

Process Parameters ◽

Supercritical Drying ◽

Peristaltic Pump ◽

Solvent Exchange ◽

Karl Fischer Titration ◽

Surface Areas ◽

Organic Aerogels ◽

Suitable System

The solvent exchange as one of the most important steps during the manufacturing process of organic aerogels was investigated. This step is crucial as a preparatory step for the supercritical drying, since the pore solvent must be soluble in supercritical carbon dioxide to enable solvent extraction. The development and subsequent optimization of a suitable system with a peristaltic pump for automatic solvent exchange proved to be a suitable approach. In addition, the influence of zeolites on the acceleration of the process was found to be beneficial. To investigate the process, the water content in acetone was determined at different times using Karl Fischer titration. The shrinkage, densities, as well as the surface areas of the aerogels were analyzed. Based on these, the influence of various process parameters on the final structure of the obtained aerogels was investigated and evaluated. Modeling on diffusion in porous materials completes this study.

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ChemInform Abstract: Carbon Dioxide Insertion Processes Involving Metal-Carbon Bonds: Solid-State and Solution Structure of (Na(18-crown-6)) (W(CO)5CH3).

ChemInform ◽

10.1002/chin.198733273 ◽

1987 ◽

Vol 18 (33) ◽

Author(s):

D. J. DARENSBOURG ◽

C. G. BAUCH ◽

A. L. RHEINGOLD

Keyword(s):

Carbon Dioxide ◽

Solid State ◽

Solution Structure ◽

Carbon Bonds

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Gellan aerogel production applying supercritical technology

Revista dos Trabalhos de Iniciação Científica da UNICAMP ◽

10.20396/revpibic262018508 ◽

2019 ◽

Author(s):

Gabriela Fujita de Freitas ◽

Julian Martinez ◽

Juliane Viganó

Keyword(s):

Carbon Dioxide ◽

High Surface ◽

High Surface Area ◽

Supercritical Drying ◽

Gelling Agent ◽

Diffusion Method ◽

Low Density ◽

Solvent Exchange ◽

Hydrogel Formulation ◽

Pre Treatment

Aerogels are materials with an open porous, low density and high surface area, which make them an interesting material to carry target compounds. The proposal of this work was to produce gellan aerogels and to study the effect of the diffusion method and internal setting method, the temperature of the gellan pre-treatment, and the addition of inulin on the aerogel shrinkage during the process. The aerogels were produced through hydrogel formulation, solvent exchange to obtain alcogel, and supercritical drying with carbon dioxide. The addition of inulin has reduced the shrinkage, but gelling methods to avoid the inulin loss must be studied, as the oil containing the gelling agent.

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Carbon dioxide insertion processes involving metal-carbon bonds: solid-state and solution structure of (18-crown-6) sodium pentacarbonylmethyltungstate(1-)

Inorganic Chemistry ◽

10.1021/ic00254a003 ◽

1987 ◽

Vol 26 (7) ◽

pp. 977-980 ◽

Cited By ~ 11

Author(s):

Donald J. Darensbourg ◽

Christopher G. Bauch ◽

Arnold L. Reingold

Keyword(s):

Carbon Dioxide ◽

Solid State ◽

Solution Structure ◽

Carbon Bonds

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Involvement of CesA4, CesA7-A/B and CesA8-A/B in secondary wall formation in Populus trichocarpa wood

Tree Physiology ◽

10.1093/treephys/tpz020 ◽

2019 ◽

Vol 40 (1) ◽

pp. 73-89 ◽

Cited By ~ 1

Author(s):

Manzar Abbas ◽

Ilona Peszlen ◽

Rui Shi ◽

Hoon Kim ◽

Rui Katahira ◽

...

Keyword(s):

Solid State ◽

Mechanical Strength ◽

Cell Walls ◽

Secondary Wall ◽

Populus Trichocarpa ◽

Wood Formation ◽

Fiber Cell ◽

Modulus Of Rupture ◽

Cellulose Content ◽

Wall Formation

Abstract Cellulose synthase A genes (CesAs) are responsible for cellulose biosynthesis in plant cell walls. In this study, functions of secondary wall cellulose synthases PtrCesA4, PtrCesA7-A/B and PtrCesA8-A/B were characterized during wood formation in Populus trichocarpa (Torr. & Gray). CesA RNAi knockdown transgenic plants exhibited stunted growth, narrow leaves, early necrosis, reduced stature, collapsed vessels, thinner fiber cell walls and extended fiber lumen diameters. In the RNAi knockdown transgenics, stems exhibited reduced mechanical strength, with reduced modulus of rupture (MOR) and modulus of elasticity (MOE). The reduced mechanical strength may be due to thinner fiber cell walls. Vessels in the xylem of the transgenics were collapsed, indicating that water transport in xylem may be affected and thus causing early necrosis in leaves. A dramatic decrease in cellulose content was observed in the RNAi knockdown transgenics. Compared with wildtype, the cellulose content was significantly decreased in the PtrCesA4, PtrCesA7 and PtrCesA8 RNAi knockdown transgenics. As a result, lignin and xylem contents were proportionally increased. The wood composition changes were confirmed by solid-state NMR, two-dimensional solution-state NMR and sum-frequency-generation vibration (SFG) analyses. Both solid-state nuclear magnetic resonance (NMR) and SFG analyses demonstrated that knockdown of PtrCesAs did not affect cellulose crystallinity index. Our results provided the evidence for the involvement of PtrCesA4, PtrCesA7-A/B and PtrCesA8-A/B in secondary cell wall formation in wood and demonstrated the pleiotropic effects of their perturbations on wood formation.

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