Well-Defined Dual Light- and Thermo-Responsive Rod-Coil Block Copolymers Containing an Azobenzene, MEO2MA and OEGMA.

Here we report the dual light- and thermo-responsive behavior of well-defined rod-coil block copolymers composed of an azobenzene unit, 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and oligo(ethylene glycol) methacrylate (OEGMA). Azobenzene-containing rigid rod blocks prepared by chain growth condensation polymerization of the azobenzene containing monomer were used as a macroinitiator of atom transfer radical polymerization (ATRP) after attaching an α-bromoisobutyryl group as an end group. Synthesis of well-defined rod-coil block copolymers with different coil block lengths was achieved by copolymerization of MEO2MA and OEGMA monomers. The synthesized polymers exhibited amphiphilic properties and polymeric micelles were formed in aqueous solution. The light-responsive behaviors of azobenzene moieties, photoisomerization by irradiation of light, and thermo-responsive behaviors of P(MEO2MA-co-OEGMA) coil blocks, aggregation by increment of temperature over lower critical solution temperature, were investigated. A dual stimuli-responsive behavior of the rod-coil block copolymers was observed when exposed to light and heat.

Homochiral Supramolecular Thin Film from Self-Assembly of Achiral Triarylamine Molecules by Circularly Polarized Light.

Here, we report the formation of homochiral supramolecular thin film from achiral molecules, by using circularly polarized light (CPL) only as a chiral source, on the condition that irradiation of CPL does not induce a photochemical change of the achiral molecules. Thin films of self-assembled structures consisting of chiral supramolecular fibrils was obtained from the triarylamine derivatives through evaporation of the self-assembled triarylamine solution. The homochiral supramolecular helices with the desired handedness was achieved by irradiation of circularly polarized visible light during the self-assembly process, and the chiral stability of supramolecular self-assembled product was achieved by photopolymerization of the diacetylene moieties at side chains of the building blocks, with irradiation of circularly polarized ultraviolet light. This work provides a novel methodology for the generation of homochiral supramolecular thin film from the corresponding achiral molecules.

Remarkably enhanced adhesion of coherently aligned catechol-terminated molecules on ultraclean ultraflat gold nanoplates.

We report the characterization and formation of catechol-terminated molecules immobilized on gold nanoplates (Au NPLs) using N-(3,4-dihydroxyphenethyl)-2-mercaptoacetamide (Cat-EAA-SH). Single-crystalline Au NPLs, synthesized using a one-step chemical vapor transport method, have ultraclean and ultraflat surfaces that make Cat-EAA-SH molecules aligned into a well-ordered network of a large-scale. Topographic study of the catechol-terminated molecules on Au NPLs using atomic force microscopy showed more orderly orientation and higher density, leading to significantly higher adhesion as observed from local force-distance curves than those on other Au surfaces. These coherently aligned catechol-terminated molecules on the atomically smooth gold surface led to significanty more reproducible and thus more physico-chemically meaningful measurements than was possible before by employing rough gold surfaces.

Reducibility of cervical disk herniation: evaluation at MR imaging during cervical traction with a nonmagnetic traction device.

The authors evaluated the reducibility of cervical disk herniation at magnetic resonance (MR) imaging performed with the patient in cervical traction. After the acquisition of neutral-state images, cervical traction images were obtained in 29 patients and seven healthy volunteers while they wore a portable intermittent traction device. During traction, all volunteers and 21 patients had a substantial increase in the length of the cervical vertebral column. The disk herniation was completely resolved in three patients and partially reduced in 18. The reducibility of cervical disk herniation can be evaluated at MR imaging performed during cervical traction.