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Subcritically dried resorcinol-formaldehyde aerogels from a base-acid catalyzed synthesis route

Laskowski, Jessica and Milow, Barbara and Ratke, Lorenz (2014) Subcritically dried resorcinol-formaldehyde aerogels from a base-acid catalyzed synthesis route. Microporous and Mesoporous Materials, 197, pp. 308-315. Elsevier. DOI: 10.1016/j.micromeso.2014.06.031 ISSN 1387-1811

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Abstract

Resorcinol-formaldehyde (RF) aerogels are prepared from a newly developed base-acid catalyzed sol-gel synthesis route. RF-gels synthesized are nanostructured and can be dried under ambient conditions without significant shrinkage. The sol-gel reaction of resorcinol (R) and formaldehyde (F) in water (W) (R/F = 0.7, R/W = 0.04) is initially catalyzed by Na2CO3 with a molar ratio of resorcinol to catalyst (R/C) of 100. After a specified time after starting the reaction (1-3 h), citric acid (1 M, 4–20 vol.-%) is added which initiates the acid catalyzed step and causes a spontaneous gelation. The time of change in pH value by adding acid is of great importance and influences the structure and properties of the material. RF-aerogels consisting of small particles much smaller than 100 nm are prepared by applying a long base catalyzed step. Particle size, density, thermal conductivity and surface area are basically independent of the amount of citric acid, but this parameter influences the mechanical resistance. A theoretical model is used to describe the time dependence of catalyst change in the sol-gel process.

Item URL in elib:https://elib.dlr.de/90065/
Document Type:Article
Additional Information:referiert
Title:Subcritically dried resorcinol-formaldehyde aerogels from a base-acid catalyzed synthesis route
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Laskowski, Jessicajessica.laskowski (at) dlr.deUNSPECIFIED
Milow, BarbaraBarbara.Milow (at) dlr.deUNSPECIFIED
Ratke, Lorenzlorenz.ratke (at) dlr.deUNSPECIFIED
Date:2014
Journal or Publication Title:Microporous and Mesoporous Materials
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:197
DOI :10.1016/j.micromeso.2014.06.031
Page Range:pp. 308-315
Publisher:Elsevier
ISSN:1387-1811
Status:Published
Keywords:Sol-gel; resorcinol-formaldehyde aerogel; base-acid catalyzed; subcritical drying
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Transport
HGF - Program Themes:Terrestrial Vehicles (old)
DLR - Research area:Transport
DLR - Program:V BF - Bodengebundene Fahrzeuge
DLR - Research theme (Project):V - Neuartige Fahrzeugkonzepte und -strukturen (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Aerogele
Deposited By: Laskowski, Jessica
Deposited On:27 Oct 2014 10:30
Last Modified:30 May 2019 22:07

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