Materials - General (including ice)
Cryo-SEM: Chalk rock saturated with brine and oil
In the first image the dark grey bubbles are dried oil droplets in brine-filled cracks. The second image shows x-ray analysis of fluids: oxygen (green) and carbon (red).
Images courtesy of the University of Stavanger, Norway.
Dendritic ice crystals
If it is cooled slowly water forms dendritic ice crystals. These can have a variety of branching patterns - the complexity of which depends upon cooling rate. Arms extend from the main body of the crystal at an angle of 60º. Some - such as the one illustrated - resemble the arms of a snowflake.
Bar: 2 µm
Water crystallises in the hexagonal system. The typical representative of that type is illustrated here as ice crystals in the form of hexagonal prisms.
Bar: 200 µm (inset: 100 µm)
Rubber particles in natural latex after freezing
Natural latex consists of a suspension of rubber particles of approximately 0.1-1 um in diameter, suspended in a buffered aqueous medium. One method for the manufacture of rubber - the Talalay process - includes a stage in which the latex is cooled to a temperature of -30ºC. As a result of the crystallization of water, the rubber particles are forced into a boundaries around the ice, where partial coalescence occurs. Cryo-SEM is the ideal method for monitoring this process.
Stable emulsion of a hydrophobic polymer
This image illustrates a stable emulsion of a synthetic liquid polymer dispersed in an aqueous continuous phase. Low-temperature SEM allows observations of dispersion phase droplet size in relation to emulsifier concentration and at higher magnification provides information about the interface between the two phases.
Bar: 10 µm
Unstable emulsion of hydrophobic polymer
This is similar to the liquid polymer in that it is again dispersed in an aqueous continuous phase. Emulsifiers are absent, however, and within a short time after dispersion coalescence or droplets within the dispersion phase starts to occur.
Bar: 10 µm
Cryo-fractured, resin-infiltrated paper
Cold fractured at -175ºC and coated with Pt. Note: titanium dioxide particles (right-hand image).
Preparation carried out on the Quorum PP3010T cryo preparation system fitted to a JEOL 7800F FE-SEM.