Photolithographic olefin metathesis polymerization

Abstract

Patterning functional materials is a central challenge across many fields of science. Despite the fact that there are hundreds of com. available photoresists, the functional diversity amongst these materials is severely limited. In most applications, the photoresist serves the sole purpose of a sacrificial mask or mold; very rarely is the resist material incorporated as a structural element or chem. functional interface. The ability to generate new kinds of chem. functional materials directly via photolithog. would enable a host of new applications, for example in microelectromech. systems (MEMS), microfluidics, patterned biomaterials and artificial optical materials. We recently reported a neg. tone photoresist using a photoactivated olefin metathesis catalyst, which can be quickly prepd. in a one-pot synthesis from com. available starting materials. Olefin metathesis is a robust synthetic methodol. that has led to new polymeric materials with many applications, such as drug delivery, org. electronics, and photonic crystals. We recently developed a method of patterning using a ruthenium photocatalyst, PhotoLithog. Olefin Metathesis Polymn. (PLOMP). In this procedure, a latent metathesis catalyst is activated by light to react with the olefins in the surrounding environment. We demonstrate a neg. tone resist by using the photocatalyst to crosslink a difunctional ROMP monomer within a matrix of linear polymer. The versatility of ruthenium-mediated olefin metathesis can now be utilized to photopattern a variety of functional materials via PLOMP, advancing the field of photoinitiated olefin metathesis from a curiosity to materials science applicable to mass microfabrication. We anticipate that PLOMP will enable the development of directly patterned micro- and nanostructures with chem., mech. and optical functionality not currently available with existing fabrication techniques.