CO2 infusion-based plastic coating
CO2 has a negative reputation for its significant contribution to global warming. However, CO2 also exhibits some positive features that may be leveraged in product manufacturing. For example, the gas may substitute for environmentally problematic solvents conventionally used in paints and coatings. Nontoxic, nonflammable, and widely available, CO2 can be utilized to impregnate plastics with durable, scratch-resistant coatings that are superior to paint.
Scientists at the Oberhausen, Germany–based Fraunhofer Institute for Environmental, Safety, and Energy Technology (UMSICHT) have developed a process to embed CO2 within polymers, such as polycarbonate and nylon. First, they heat the gas to 30.1°C at a pressure of 73.8 bar, imparting it with solvent-like characteristics. In this state, it functions as a vehicle for dyes and other additives. Increasing the pressure to 170 bar allows powdered pigment to be dissolved completely into the CO2 and subsequently into its plastic carrier. The process requires only a few minutes and completely encapsulates the pigment within the plastic.
In addition to being used with durable coatings, the method may also be used with additives, such as antibacterial coatings and medical compounds. The researchers conducted tests demonstrating that CO2-impregnated polycarbonate is suitable for mobile device casings or door handles that eliminate E. coli bacteria, for example. They also speculate that the process could be used to manufacture colored contact lenses that release pharmaceutical compounds over a controlled period.
Contact: Fraunhofer UMSICHT, Oberhausen, Germany.
For more information, see Transmaterial Next: A Catalog of Materials that Redefine Our Future