Alignment of Perfluorinated Supramolecular Columns on the Surfaces of Various Self-Assembled Monolayers

Abstract

We studied the orientation of the hexagonal columnar mesophase formed by self-organization of a perfluorinated supramolecular dendrimer containing a carboxyl (-COOH) headgroup and three perfluorinated (-CF 3) tails at surfaces modified with self-assembled monolayers (SAMs). The SAMmodified surfaces studied were composed of an Au(111) substrate modified with one of five types of SAM. The SAM molecules used all had an -SH headgroup, but different terminal groups (-CF 3, -CH3, and -OH) and different spacer chain lengths. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and contact angle microscopy results revealed that the lattice parameters and structure of the perfluorinated supramolecular dendrimer are retained, but the orientation of the columns is strongly affected by the characteristics of the SAM surface. The supramolecular columns took on a planar alignment on the -CF 3 and -OH terminated SAM surfaces, but exhibited a perpendicular orientation on the -CH3 terminated SAM surface. These variations in column alignment can be attributed to the types of molecular interactions between the terminal groups of the SAM molecules and the perfluorinated core/tails of the supramolecular columns. However, the surface morphology and orientation was not affected by changing the space chain length of the SAM molecules used.

Interfacial reactions on Pb-free solders with Au/Pd/Ni/Cu multilayer substrates

“…The eutectic temperature of SZ solder is 198 • C, which is very close to the melting temperature of the Sn-37Pb solder (183 • C). Furthermore, beside the lower process discrepancy between SZ and Sn-37Pb solder, SZ solder is observed to demonstrate better mechanical properties than the Sn-37Pb solder [8].…”

“…In recent years, owing to the increase in the global environmental consciousness and aggressive passing of related Pb-banning laws by the European Union, such as WEEE and RoHS, conventional Sn-Pb solders have been replaced by Pb-free solders since July 1, 2006 [4]. Many Pb-free solders have been developed, such as pure Sn, Sn-3.0 wt% Ag-0.5 wt% Cu (SAC), Sn-0.7 wt% Cu (SC), Sn-58.0 wt% Bi (SB) and Sn-9.0 wt% Zn (SZ), which are the most promising Pbfree solders [5][6][7][8][9][10].…”

Surface ordering of a rod-coil block molecule on the water subphase

“…Bright field phase-contrast TEM micrographs were obtained by low-dose procedures, before the observation samples were slightly stained with RuO 4 vapor for the heightening of the mass contrast. TEM images were recorded on SO-163 plates at appropriate under-focus conditions [3,12]. …”

Large‐Area, Highly Aligned Cylindrical Perfluorinated Supramolecular Dendrimers Using Magnetic Fields

“…[2][3][4]13,21] Here we report on a dramatic improvement in the degree of control and selectivity in the orientation of fan-shaped supramolecular cylinders over large areas; this has been achieved by applied magnetic fields. We show that these cylindrical domains become aligned perpendicular to the magnetic field direction, with the aromatic parts of the cylinders orienting themselves parallel to the magnetic-field vector.…”

“…This method can be used to create a grain size in the plane of the film that is much larger than that which can be achieved using surface alignment techniques. [2][3][4] Our strategy relies on the magnetic-field-induced alignment of aromatic molecular materials due to the diamagnetic properties of aromatic groups.[22] Calamitic liquid crystals containing aromatic groups have a positive diamagnetic anisotropy, whereas discotic liquid crystals have a negative diamagnetic anisotropy. This is due to the component of the diamagnetic susceptibility perpendicular to a benzene ring being greater than the in-plane component.…”