Patterning of triblock copolymer film and its application for surface-enhanced Raman scattering

In this paper,microphase behavior of an ABC triblock copolymer,polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide),namely PS-b-P2VP-b-PEO,was systematically studied during spin-coating and solvent vapor annealing based on various parameters,including the types of the solvent,spin speed and thickness.The morphological features and the microdomain location of the different blocks were characterized by atomic force microscope (AFM) and high resolution transmission electron microscopy (HRTEM).With increasing thickness,the order-order transition from nanopores array to the pattern of nanostripes was observed due to microdomain coarsening.These processes of pattern transformation were based on the selectivity of toluene for different blocks and on the contact time between solvent molecules and the three blocks.This work provides different templates for preparation of gold nanoparticle array on silicon wafer,which can be adopted as an active surface-enhanced Raman scattering (SERS) substrate for poly(3-hexylthiophene) (P3HT).     

Three-dimensional Bi2Se3 nanopattern films self-assembled with ultrathin nanosheets on the surface of Se nanotubes

Regular three-dimensional (3D) rose-like Bi₂Se₃ nanopattern film is fabricated through a simple chemical route. This nanopattern film is self-assembled with ultrathin Bi₂Se₃ nanosheets having thicknesses of less than 8 nm. The Bi₂Se₃ nanosheets were formed on the surface of Se nanotubes, and the Se nanotubes were used as both the Se resource and the substrate to support the growth of the Bi₂Se₃ nanopattern film. Since several length scales are involved in this confined 3D structure, which are developed at different time, during the formation of the micro-structure, a careful control of these length scales is expected to provide new opportunities for engineering the boundary scattering of phonons of different wavelengths and developing new thermoelectric materials with novel properties.     

Patterned Peptide Multilayer Thin Films with Nanoscale Order Through Engineered Liquid Crystallinity

Self‐assembling polypeptide molecules have been designed to explore aspects of hierarchical or multiscale long‐range order, and the interactions that occur at various length scales that drive order and patterning in complex materials. Three peptides were synthesized with repetitive motifs loosely based on insect silks. Thin films were obtained from each peptide using a solvent templating technique. Smectic layers were observed in the thin films and in bulk materials prepared for comparison. A variety of additional effects, including chirality and interfacial anchoring at the helix, compete in the thin films, resulting in complex but regular patterns within the materials over a hierarchy of length scales spanning several orders of magnitude. The relative magnitude of these effects can be tuned through sequence design, as can the smectic layer thickness. Thus, many parameters describing the patterns in the materials can be controlled at the molecular design level, allowing complex patterns of nanoscale to microscale topography and chemistry to be created through self‐assembly. In addition to the potential for designer materials, there may be some biological relevance to the observed phenomena. The silk‐like molecules used fold into “hairpins,” providing a rigid unit that can drive liquid crystalline phase behavior. A similar process could be at work in silks and other structurally similar proteins that form textured materials. Chiral smectic order and multiscale patterns that can often result are clearly rich areas, worthy of further exploration.