High density arrays of chromium (Cr) and layered gold/chromium (Au/Cr) nanodots and nanoholes in metal films were fabricated by evaporation onto nanoporous templates produced by the self-assembly of poly(styrene-b-methyl methacrylate) (P(S-b-MMA)) diblock copolymers. The cylindrical microdomains of the asymmetric block copolymer were oriented normal to the surface by balancing interfacial interactions of the blocks with the substrate. By selectively removing either the minor or major component, nanoporous films of PS or nanoscopic posts of PS could be produced. Thus, a template, comprising an array of hexagonally packed pores in a PS matrix or PS posts, was easily fabricated. Evaporation of Cr and Au onto the template, followed by sonication and UV degradation of the PS, left Cr or Au/Cr nanodots or a nanoporous metallic film.

Nonlithographic techniques for patterning structures on the nanometer scale can provide methods for direct control of particle spacing at surfaces. By using diblock copolymers, the surface density of a film can be established by the properties and area of the anchoring block, and the feature sizes can be set through the choice of free block dimensions. By depositing poly(styrene)-poly(ethylene oxide) (PS-PEO) diblock copolymers of different fractional composition of PEO on a surface by a Langmuir-Blodgett technique at different pressures, we show that the surface density of poly(styrene) aggregates can be controlled. The separation of PS aggregates on the surface is ensured by selection of the PEO composition so that its projected area is greater than that of the PS for all pressures less than that of the transition from a 2-dimensional to 3-dimensional film. The areal density of these resultant PS surface micelles can be tuned for a particular polymer composition and is linearly dependent on the deposition pressure which defines the region chosen on the phase diagram.

The patterning of surfaces on the nanometer scale is desirable for a variety of applications ranging from membranes to magnetic data storage.[1±4] Block copolymers provide a very promising route to this goal since they self-assemble into ordered arrays of nanostructures, [5±10] where the size is dictated by the molecular weight, and the type of morphology depends on the volume fractions of the blocks. However, control over domain orientation and lateral order of these arrays in thin films has been a challenge. Preferential wetting of a surface by one of the blocks typically results in the orientation of the copolymer microdomains parallel to the substrate, and the film thickness is quantized by the equilibrium period, L 0 . As the film thickness (D) approaches L 0 , the orientation of the microdomains becomes increasingly dictated by the strength of interfacial interactions and the commensurability of L 0 in relation to D. [11] In the case of a confined thin film, incommensurability of L 0 causes either a stretching or compression of the period or a reorientation of the structure normal to the surface. In thin films where the surface is not confined, control over the interfacial interactions has provided a simple route to control the orientation.[12] For thicker films, external fields (i.e., an electric field) have proven to be very effective in controlling the orientation of the microdomains. [13,14] Here, the spontaneous ordering of cylindrical microdomains in thin films of a metal-containing polyferrocene block copolymer perpendicular to a substrate surface is demonstrated. In addition, the pyrolysis of the ordered films to generate patterned arrays of ceramic nanostructures is described.Most studies of block copolymer self-assembly performed to date have focused on organic materials. Metal-containing block copolymers offer additional opportunities for the creation of functional nanostructured materials. [15,16] In this study, the microphase separation in thin films of an amorphous organic±organometallic block copolymer is discussed. Asymmetric poly(styrene-b-ferrocenylethylmethylsilane) block copolymers (PS 374 -b-PFS 45 , number average molecular weight, M n = 52 000 g mol ±1 , polydispersity index (PDI) = 1.21, PS volume fraction of 0.806) having cylindrical domains of PFS block in a PS matrix were studied. The copolymers were prepared by sequential anionic ring-opening polymerization (ROP) as described previously. [17,18] The T g of the PFS block is 19 C, whereas the T g of the PS block is~100 C. This contrasts with symmetrically substituted polyferrocenylsilanes, where the T g of the PFS block is significantly higher and the PFS block crystallizes. Both perturb microphase separation. [19±21] Small-angle X-ray scattering (SAXS) studies of a thermally annealed bulk sample of PS 374 -b-PFS 45 gave a scattering pattern consistent with a cylindrical morphology with a period of 33 nm, as shown in Figure 1. A series of PS 374 -b-PFS 45 films were prepared by spin coating the diblock copolymer onto silicon waf...

Electrohydrodynamics were studied in a trilayer thin film system consisting of two different polymeric layers and air. A polymer with a higher dielectric constant, poly(methyl methacrylate), was sandwiched between air and a lower dielectric constant polymer, polystyrene. An electric field was applied normal to the interfaces. Along with electrostatic forces, dewetting forces were significant at two of the interfaces, namely, the polystyrene/silicon wafer and the polystyrene/poly(methyl methacrylate) interfaces. These two combined forces produce novel closed-cell structures that are difficult to produce by other existing techniques.