Structures in Multicomponent Polymer Films: Their Formation, Observation and Applications in Electronics and Biotechnology

摘要

Several strategies to form multicomponent films of functional polymers, with micron, submicron and nanometer structures, intended for plastic electronics and biotechnology are presented. These approaches axe based on film deposition from polymer solution onto a rotating substrate (spin-casting), a method implemented already on manufacturing lines. Film structures are determined with compositional (nanometer) depth profiling and (submicron) imaging modes of dynamic secondary ion mass spectrometry, near-field scanning optical microscopy (with submicron resolution) and scanning probe microscopy (revealing nanometer features). Self-organization of spin-cast polymer mixtures is discussed in detail, since it offers a one-step process to deposit and align simultaneously domains, rich in different polymers, forming various device elements: (ⅰ) Surface segregation drives self-stratification of nanometer lamellae for solar cells and anisotropic conductors, (ⅱ) Cohesion energy density controls morphological transition from lamellar (optimal for encapsulated transistors) to lateral structures (suggested for light emitting diodes with variable color), (ⅲ) Selective adhesion to substrate microtemplates, patterned chemically, orders lateral structures for plastic circuitries, (ⅳ) Submicron imprints of water droplets (breath figures) decorate selectively micron-sized domains, and can be used in devices with hierarchic structure. In addition, selective protein adsorption to regular polymer micropatterns, formed with soft lithography after spin-casting, suggests applications in protein chip technology. An approach to reduce lateral blend film structures to submicron scale is also presented, based on (annealed) films of multicomponent nanoparticles.