ABSTRACT:A new phenylated diamine, bis(4-amino-2-biphenyl)ether, was synthesized in five steps starting from 3-chloro-4-fluoronitrobenzene. New aromatic polyimides having phenyl groups at the 2-and 2 0 -positions of the diphenyl ether moiety were prepared from this diamine and various tetracarboxylic dianhydrides by the conventional two-step procedure that included ring-opening polymerization in NMP and subsequent thermal cyclic dehydration. The polyimides were characterized by differential scanning calorimetry (DSC), thermogravimetry, and dynamic mechanical analysis (DMA). Typical polyimides showed excellent thermal stability, and had glass transition temperature (T g ) above 250 C. As for the series of polyimides prepared from tetracarboxylic anhydrides having linear phenylene moiety, the introduction of phenyl group at the 2-and 2 0 -positions of phenyl ether improved thermal and thermo-mechanical properties as well as the solubility of polymers.

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Reflection from various surfaces of many optical systems, such as photovoltaics and displays, is a critical issue for their performance, and antireflection coatings play a pivotal role in a wide variety of optical technologies, reducing light reflectance loss and hence maximizing light transmission. With the current movement toward optically transparent polymeric media and coatings for antireflection technology, the need for economical and environmentally friendly materials and methods without dependence on shape or size has clearly been apparent. Herein, we demonstrate novel antireflection coatings composed of chitin nanofibers (CHINFs), extracted from crab shell as a biomass material through an aqueous-based layer-by-layer self-assembly process to control the porosity. Increasing the number of air spaces inside the membrane led low refractive index, and precise control of refractive index derived from the stacking of the CHINFs achieved the highest transmittance with investigating the surface structure and the refractive index depending on the solution pH. At a wavelength of 550 nm, the transmittance of the coatings was 96.4%, which was 4.8% higher than that of a glass substrate, and their refractive index was 1.30. Further critical properties of the films were the durability and the antifogging performance derived from the mechanical stability and hydrophilicity of CHINFs, respectively. The present study may contribute to a development of systematically designed nanofibrous films which are suitable for optical applications operating at a broadband visible wavelength with durability and antifog surfaces.

We fabricated slippery liquid-immobilized coating (SLIC) films by reacting a slippery liquid (polymethylhydrosiloxane) near the surface of a polyelectrolyte film containing silver ions prepared by the layer-by-layer method. The obtained films maintained their slipperiness after chemical and physical treatments, in contrast to slippery liquid-infused porous surfaces. The high chemical and physical stabilities of the films were attributable to gelation and immobilization of the lubricant owing to an oxidation-reduction reaction with subsequent dehydration condensation of Si-OH on the outer surface of the polyelectrolyte film and the bonding of Si-H with NH groups within the polyelectrolyte film, respectively. Moreover, the SLIC films exhibited a high degree of slipperiness with respect to low-surface-tension liquids. To the best of our knowledge, this technique of lubricant immobilization using silver ions has not been reported previously. The films should be suitable for use in various applications where contamination must be prevented under extreme conditions, such as those requiring high physical durability and organic solvent use.

Aromatic polyimides having phenyl groups at the 2- and 2′-positions of the diphenyl ether moiety were synthesized from bis(4-amino-2-biphenyl) ether and various tetracarboxylic dianhydrides by the conventional two-step procedure using N-methyl-2-pyrrolidone (NMP) as a solvent [Morikawa et al., Polymer Journal37, 759, 2005]. The phenyl groups at the 2,2′-position of the phenyl ether improved the solubility of polyimides without decreasing the thermal and thermo-mechanical properties. In this paper, soluble polyimides were synthesized in a one-step procedure by reacting this diamine with various tetracarboxylic dianhydrides in m-cresol at 190°C, and the properties, especially the thermal properties, thermo-mechanical properties and solubility were compared with those of the polyimides synthesized by the two-step procedure.