Foam polymers — which are useful because they are light and rigid — now can get into the nooks and crannies of or curve around commercial, medical, and industrial products because of a new process developed by scientists at the University of Rochester.
The key to making highly customizable coatings of the foam-like polymers is to grow the polymers directly from gases, according to a press release from the university. Mitchell Anthamatten, an associate professor of chemical engineering, used a chemical vapor deposition system that converted a mixture of gases into foam polymers.
“With this process we can grow polymer coatings in which the density and pore structure varies in space,” says Anthamatten. “My hope is that the research leads to applications in a wide variety of fields, including medical, manufacturing, and high-tech research.”
The system Anthamatten developed with a graduate student involved a mixture of gases that were pumped into a low-pressure reactor containing a cold surface to encourage condensation. The press release explains further the process:
One of the condensed liquids actually forms the polymer material (think of the solid part of a sponge), while the other one temporarily occupies the spaces that become the pores in the foam material (think of the hollow part of a sponge). But the problem is that the liquids in the film don’t mix well — very much like water and oil. What’s required is to quickly solidify the polymer film, just as the two liquids begin to separate from one another. By controlling the solidification rate, they could control the size and distribution of the pores; the faster the coating is solidified, the smaller the pores become.
The variables in the process can be adjusted: the rate at which the gas can be fed into the system, the temperature of the cold surface in the reactor, and the type of chemical agent. Playing with those variables yields foam polymers with different densities, thicknesses, shapes, and hole-sizes.
“This process is highly customizable, meaning that we can make adjustments along the way, shaping the material’s pore structure and density as it is grown,” says Anthamatten. “As a result, it will be easier to put foam polymers in hard-to-get-at places, or even on curved surfaces.”
These foam materials can be used in a variety of ways, from creating seals and gaskets, to surface coatings, to synthetic fibers, and hard plastic parts, for electronic or medical instruments. If a manufacturer of one of these products wanted to know how durable or tough it was, technicians at Polymer Solutions can test the strain that it can sustain.
Source: “Turning Vapors into Foam-Like Polymer Coatings,” University of Rochester, 10/14/13
Image by Adam Fenster/University of Rochester, used with permission.