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The morphology and orientation of polymer crystals are important factors which determine the performance of thin-film, polymer-based technologies such as organic electronic devices and gas separation membranes. Here, we utilize polymer-substrate epitaxy to achieve a highly oriented crystalline morphology during thin-film processing. To accomplish this, we employ matrixassisted pulsed laser evaporation (MAPLE), a slow physical vapor deposition process, to deposit linear polyethylene epitaxially atop a graphene substrate. Via MAPLE, we demonstrate the ability to achieve a film morphology comprised of well-aligned, edge-on crystalline lamellae. Furthermore, we show that MAPLE can be exploited to grow crystalline lamellae composed entirely of extended polymer chains which exhibit a near-equilibrium melting temperature. Our study demonstrates that MAPLE, as a bottom-up approach, can deposit polymer thin films with improved control over crystalline morphology. KEYWORDS epitaxial polymer crystallization, graphene, grazing-incidence x-ray diffraction, matrixassisted pulsed laser evaporation, melting, 1 | INTRODUCTION Enforcing the crystallization of polymers into a desired thin-film morphology remains a major scientific challenge. [4] Yet, the morphology is a critical factor determining the performance of [...]

A study was conducted to demonstrate the feasibility of immobilizing a bilayer-forming surfactant onto an ion-exchange resin with retention of gel to liquid-crystalline phase transition behavior. The results confirmed the retention of a gel to liquid-crystalline phase transition of the surfactant occurring between 296 and 318 K.

A study was conducted of electroluminescent devices made from single-layer doped polymer blend thin films having bipolar carrier transport abilities. Very efficient transfer of energy can happer from the host to very dilute amounts of emitting materials in photoluminescence. Excitons seem to be formed at doped emitting centers rather than in the host in electroluminescence. A relatively high external quantum efficiency and a low operating voltage are attainable with this class of devices.

Dense periodic arrays of holes and dots have been fabricated in a silicon nitride-coated silicon wafer. The holes are 20 nanometers across, 40 nanometers apart, and hexagonally ordered with a polygrain structure that has an average grain size of 10 by 10. Spin-coated diblock copolymer thin films with well-ordered spherical or cylindrical microdomains were used as the templates. The microdomain patterns were transferred directly to the underlying silicon nitride layer by two complementary techniques that resulted in opposite tones of the patterns. This process opens a route for nanometer-scale surface patterning by means of spontaneous self-assembly in synthetic materials on length scales that are difficult to obtain by standard semiconductor lithography techniques., In general, feature sizes greater than 300 nm are routinely produced by photolithography techniques. For feature sizes between 300 and 30 nm, electron beam lithography is commonly used. However, feature [...]

Three commercial styrenic triblock copolymers were subjected to planar extension in a lubricated channel die, as a model for the orientation that may occur during processing operations. Materials that contain cylinders of polystyrene show a pronounced orientation of the cylinder axis in the flow direction, as revealed by small-angle X-ray scattering in the three orthogonal directions. This anisotropy produces small-strain tensile moduli that differ by a factor of 10 or more in the two in-plane directions. A material that contains lamellae of polystyrene shows pronounced orientation of the lamellae in the plane of the sample; in particular, lamellar normals are strongly forbidden from pointing along the flow direction. For similar strains, planar extension is much more effective in orienting these materials than simple shear., INTRODUCTION Styrenic block copolymers are widely used as thermoplastic elastomers (1). The most common of these are triblock copolymers, with two styrene end-blocks and a midblock of a rubbery polymer, [...]