Synthesis, Characterization, and Optical Properties of Uniaxially Drawn and Gold Nanoparticle Dispersed Fluorinated Polyimide Films.

Abstract

Gold-nanoparticle dispersed fluorinated Polyimide films were prepared by thermal curing and uniaxially drawing of poly(amic acid) films containing hydrogen tetrachloroaurate(III) trihydrate (HAuC14•3H2O) as a dopant. The chemical states, crystallinity, average sizes, and spatial distribution of the gold particles were examined, and the optical and thermal properties of the films were compared with those of the host-polyimide. The gold salt was converted into zero-valent gold particles having high crystallinity after thermal imidization. TEM micrograph showed that the precipitated gold nanoparticles inside the films are larger than those in the surface area, and they have well-defined lozenge or rectangular shapes, which suggest pressed octahedron or rectangular parallelepiped structures of the crystallites. In addition, their long axes are oriented along the drawing direction and the surface direction. The films show much higher absorption in the visible region than the host-polyimide, which is due to the surface plasmon absorption of gold nanoparticles. In addition, significant anisotropy in optical transmittance are observed for the Au-dispersed films. This supports the orientation of precipitated gold nanoparticles having anisotropic shapes along the drawing direction.

Photoinduced Generation of Noble Metal Nanoparticles Into Polymer Matrices and Methods for the Characterization of the Derived Nanocomposite Films

“…This produces zerovalent metal or metal-sulfide nanoparticles, depending on the metal and conditions. The literature also reports similar interesting composites prepared by the inclusion of metal nitrates (e.g., AgNO 3 ) [44][45][46][47] and metal salts (e.g., HAuCl 4 ) [48]. In these methods organic by-products are left trapped in the polymer, and the reduction of the metal causes damage to the substrate by electron extraction.…”

Latent Synthesis of Electrically Conductive Surface-Silvered Polyimide Films

“…Recently, in the polyimide domain, attention has focused on the use of fluorinated polyimides as materials for electrical and electro-optical devices − , often having metallic phases coupled with the polyimide ,,− . Fluorine-containing polyimides possess several enhanced properties relative to traditional polyimides (e.g., Kapton, Upilex R and S, and Ultem), including fully imidized as well as amic acid forms that are soluble in organic solvents, lower dielectric constants, lower moisture absorption, and such marked transparency in the visible region of the electromagnetic spectrum that fluorinated polyimides are often referred to as “colorless” polyimides .…”

Generation Behaviors of Optical Anisotropy Caused by Silver Nanoparticles Precipitated in Uniaxially Drawn Polyimide Films

“…14) In addition, when the PAA films were cured with uniaxial drawing, distinct anisotropies in optical transmittance were observed in the films due to the precipitation of metal nanoparticles in the oriented polymer matrix. [15][16][17][18] In the case of using silver nitrate (AgNO 3 ) as a dopant, a significant anisotropy in optical transmittance was observed in a wide wavelength region (500-1000 nm), and the wavelength dispersion of the anisotropy can be controlled by varying the degree of polymer orientation. 15) The optical anisotropy strongly depends on the preparation conditions of PI films, such as curing atmospheres and holding times during thermal curing at the final curing temperature.…”