CONSPECTUSIn this Account, we describe the use of perfluoropolyether (PFPE)-based materials that are able to accurately mold and replicate micro-and nanosized features using traditional techniques such as embossing as well as new techniques that we developed to exploit the exceptional surface characteristics of fluorinated substrates. Because of the unique partial wetting and nonwetting characteristics of PFPEs, we were able to go beyond the usual molding and imprint lithography approaches and have created a technique called PRINT (Particle [ PRINT is a distinctive "top-down" fabrication technique capable of generating isolated particles, arrays of particles, and arrays of patterned features for a plethora of applications in both nanomedicine and materials science. A particular strength of the PRINT technology is the high-resolution molding of well-defined particles with precise control over size, shape, deformability, and surface chemistry. The level of replication obtained showcases some of the unique characteristics of PFPE molding materials. In particular, these materials arise from very low surface energy precursors with positive spreading coefficients, can be photocured at ambient temperature, and are minimally adhesive, nonswelling, and conformable. These distinctive features enable the molding of materials with unique attributes and nanometer resolution that have unprecedented scientific and technological value. For example, in nanomedicine, the use of PFPE materials with the PRINT technique allows us to design particles in which we can tailor key therapeutic parameters such as bioavailability, biodistribution, target-specific cell penetration, and controlled cargo release. Similarly, in materials science, we can fabricate optical films and lens arrays, replicate complex, naturally occurring objects such as adenovirus particles, and create 2D patterned arrays of inorganic oxides.
IntroductionReplication of submicrometer features is a challenging materials problem. The past few decades have witnessed the emergence of soft lithography as an important tool for low cost pattern replication on the micrometer and nanometer scale. 1 Soft lithography uses embossing and stamping techniques with applied forces as an alternative to photolithography for the manufacture of integrated circuits and other devices with sub-50 nm feature sizes. Embossing typically involves the patterning of materials such as polymers, organics, and biological molecules into continuous arrays of patterned features using molds made from either hard materials (quartz/glass, glassy polymers) or soft elastomeric materials to generate features that form on top of an interconnecting flash layer. 1-3 The field of soft lithography has traditionally been dominated by the elastomer poly(dimethylsiloxane) (PDMS). 4,5 Despite the advantage of PDMS for use in soft lithography, it has been shown to suffer from serious drawbacks Embossing is the process of creating a three-dimensional image or design in paper and in ductile materials. It is typically acc...
