Düsseldorf — Wacker, the Munich-based chemicals group, showed off its newly developed Elastosil silicone film, made entirely from silicone elastomers and available as roll stock in thicknesses down to 20 microns, with an accuracy of 5%.
As Andreas Köllnberger, manager global product development engineering silicones at Wacker, noted: "It's a completely new dosage form for silicone. Normally, it's press molded or injection molded. The new film is formed via a patent-registered production process that provides these extremely uniform thicknesses."
These films are manufactured in cleanroom conditions without the use of solvents, and come with an intermediate backing for easy handling, from which they can easily be peeled off.
Elastosil film, says Köllnberger, is highly suited for gas-permeable packaging and protective film applications. The film is permeable to water vapor and certain gases such as oxygen, nitrogen and carbon dioxide, but not to water. "Its properties are very stable. Other applications are, for example, in gas separation technology - it can be used as a membrane for separating or enriching gases," he said. "Its breathability also makes it a good replacement for polyurethane in, for example, wound dressings."
A very exciting - future - application would be to use the new film as an electroactive polymer (EAP). As a silicone, it's electrically insulating, with good dielectric properties. EAPs are able to alter their shape when a voltage is applied. As a result, silicon films can be used to design innovative sensors, actuators and generators. It's here, says Köllnberger, that the 5% thickness accuracy of the Elastosil films are important: Application of a voltage to a single actuator base unit produces a deformation of just a few microns - not enough for industrial use. However, if large numbers of them are stacked together, and connected up in parallel, changes in the order of several millimeters and even centimeters are possible. These stacks, which can have any shape, can be used to generate different types of movement. Potential applications range from toys, electrical relays and electrically operated valves to artificial limbs and peristaltic pumps.
Köllnberger: "And even further on the horizon is another a revolutionary application: we are working on a project in which stacks of these silicone films can function as a generator to harvest energy from ocean waves. 30% of the costs in conventional wave power generation projects go towards maintenance of the moving parts. Our technology eliminates all moving parts, which makes these systems virtually maintenance free and significantly cheaper to operate. They could spend 20 years in the ocean and still work perfectly."
That application is still a long way away. The actuators, however, may be on the market as soon as another 2-3 years, and Wacker is also exploring other properties of the film that could be exploited in the future.