High resolution transmission electron microscopy of melamine-formaldehyde aerogels and silica aerogels

Technical Report · Sun Sep 01 00:00:00 EDT 1991

DOI:https://doi.org/10.2172/6186167· OSTI ID:6186167

Ruben, G C ^[1]

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1. Dartmouth Coll., Hanover, NH (United States). Dept. of Biological Sciences

The goal of the high resolution transmission electron microscopy (HRTEM) was to image the structure of two tetramethyl orthosilicate (TMOS) and two melamine-formaldehyde (MF) aerogels at the single polymer chain level{sup 1,2}. With this level of structural resolution we hoped to interrelate each aerogel's structure with its physical properties and its method of synthesis. Conventional single-step base catalysed TMOS aerogels show strings of spheroidal particles linked together with minimal necking. The spheroidal particles range from 86--132 {Angstrom} and average 113{plus minus}10 {Angstrom} in diameter{sup 2}. In contrast the TMOS aerogels reported on here were made by a two step method. After extended silica chains are grown in solution under acidic conditions with a substoichiometric amount of water, the reaction is stopped and the methanol hydrolysed from TMOS is removed. Then base catalysis and additional water are added to cause gel formation is a nonalcoholic solvent. The MF aerogels were prepared for HRTEM by fracturing them on a stereo microscope stage with razor knife so that fractured pieces with smooth flat surfaces could be selected for platinum-carbon replication. The two silica (TMOS) aerogels were both transparent and difficult to see. These aerogels were fractured on a stereo microscope stage with tweezers. 6 refs., 4 figs.

• Research Organization: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dartmouth Coll., Hanover, NH (United States). Dept. of Biological Sciences
• Sponsoring Organization: USDOE; USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6186167
• Report Number(s): UCRL-CR-108760; ON: DE92002765
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
GELS
TRANSMISSION ELECTRON MICROSCOPY
FOAMS
FORMALDEHYDE
MELAMINE
REPLICA TECHNIQUES
SILICA
SPATIAL RESOLUTION
ALDEHYDES
AMINES
AZINES
CHALCOGENIDES
COLLOIDS
DISPERSIONS
ELECTRON MICROSCOPY
HETEROCYCLIC COMPOUNDS
MICROSCOPY
MINERALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
RESOLUTION
SILICON COMPOUNDS
SILICON OXIDES
TRIAZINES
360602* - Other Materials- Structure & Phase Studies
665300 - Interactions Between Beams & Condensed Matter- (1992-)