Ink‐Jet Printing of Functional Polymers and Materials: A (Future) Key Technology in Polymer Science

Ink-jet printing is a familiar method for transferring digital data to paper. It is now at the point where it is challenging conventional silver-halide photography, with digital photographic ink-jet printouts rapidly becoming more durable and more resolved. However, ink-jet technology nowadays is more than just a printing technique, it has become a versatile tool in various industrial processes to deposit tiny amounts of liquid material in an extremely controlled and defined manner. Examples include solder for the fabrication of print boards, lubricants for the lubrication of micromechanical parts, and UV-curable resins for the manufacturing of entire micro-optical parts, like waveguides, microlenses and arrays thereof. Ink-jet printing is also considered as one of the key technologies in the field of defined polymer deposition, in particular in relation to plastic electronics. The plastic electronics market is expected to grow very rapidly over the coming years, which is due to the ease of processing the corresponding conductive and electroluminescent polymers. Ink-jet printing is one of the methods of choice because of its flexibility, low cost and ease of mass production. Ink-jet printed multicolor polymer light emitting diode (pLED) displays will soon enter the market for consumer electronics. Pilot lines are now being built for the manufacturing of thin-film transistors and RFID transponders, although many other applications of ink-jet printing, for example, in high-throughput experimentation, biochip manufacturing or rapid prototyping, are still being studied. However, the application of ink-jet printing in these fields is far from trivial. This is partially a result of the requirements in terms of resolution, which are much higher than in the graphics industry. The rheological properties of polymer solutions require the use of dilute solutions, giving rise to many additional problems related to solute deposition. These and other problems were discussed during the first Dutch Polymer Institute (DPI) workshop on Ink-Jet Printing of Functional Polymers and Materials in Eindhoven (28th. June 2004), organized by Dr. Berend-Jan de Gans. Numerous scientists from academia, research institutes and industry took the chance to discuss the role of ink-jet printing in their specific area of expertise, and thereby triggered the preparation of a special section in Macromolecular Rapid Communications. We hope that this collection of contributions will stimulate further research in this new and exciting field.