Robin E. Southward

Reflective and electrically conductive surface silvered polyimide films and coatings prepared via unusual single-stage self-metallization techniques

Highly reflective and/or surface conductive flexible polyimide films can be prepared by the incorporation of positive valent silver compounds into solutions of poly(amic acid)s formed from a variety of dianhydrides and diamines. Thermal curing of selected silver(I)-containing poly(amic acid)s leads to cycloimidization of the polyimide precursor with concomitant silver(I) reduction and surface aggregation of the metal yielding a reflective and/or conductive silver surface similar to that of the native metal. However, not all silver(I) precursors are effective surface metallization agents and not all poly(amic acid)s metallize with equal facility. Ligand/anion and polyimide structural effects on film metallization efficacy and on physical properties on metallized films are reviewed.

Reflective and conductive silvered polyimide films for space applications prepared via a novel single-stage self-metallization technique

Abstract Highly reflective and surface conductive flexible polyimide films have been prepared by the incorporation of silver(I) acetate and 1,1,1-trifluoro-2,4-pentanedione into a dimethylacetamide solution of poly(amic acid), formed from 3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride and 4,4′-oxydianiline. Thermal curing of the silver(I)-containing poly(amic acid) leads to cycloimidization of the polyimide precursor with concomitant silver(I) reduction yielding a reflective and conductive silvered surface with properties approaching those of the native metal. Ligand/anion effects on the metallization process resulted when using additional silver(I) compounds including: silver(I) nitrate; silver(I) tetrafluoroborate; (trifluoroacetato)silver(I); (hexafluoroacetylacetonato)silver(I); (trifluoroacetylacetonato)silver(I); and 1-(2-thienyl)-3,3,3(trifluoroacetonato)silver(I). Comparisons among these six silver(I) compounds as precursors for the surface metallization of BTDA/4,4′–ODA are discussed with regard to reflectivity, conductivity and surface morphology. The metallized films usually retain the essential mechanical properties and thermal properties of a parent film. Films were characterized by X-ray diffraction, transmission and scanning electron microscopy, tapping mode atomic force microscopy and X-ray photoelectron spectroscopy. Also, electrical conductivity, reflectivity, differential scanning calorimetric, thermal gravimetric and mechanical measurements were made on the metallized films.

Synthesis of hexafluoroisopropylidene-containing polyimide-silver nanocomposite films evolving specularly reflective metal surfaces

Highly reflective surface-metallized flexible polyimide films have been prepared by the incorporation of the soluble silver ion complex (1,1,1-trifluoroacetylacetonato)silver(I) into dimethylacetamide solutions of the poly(amic acid) prepared from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane (4-BDAF). Thermal curing to 300 °C of solution cast silver(I)poly(amic acid) films leads to cycloimidization of the amic acid with concomitant silver(I) reduction and formation of a reflective surface-silvered film from 6–13% weight percent silver. The reflective surfaces evolve only when the cure temperature reaches 300 °C. After achieving a maximum value the reflectivity abruptly drops with further heating at 300 °C and the polyimide suffers oxidation degradation. The metallized films are thermally stable and maintain mechanical properties similar to those of the parent polyimide. TEM reveals that the interior of the composite films have ca. 5–20 nanometer-sized silver particles. SEM shows surface silver particles from ca. 50–1000 nm whose size varies with cure time at 300 °C. Neither the bulk nor the surface of the films is electrically conductive. There is strong interfacial adhesion of metal to polyimide.

Flexible Fabrics with High Thermal Conductivity for Advanced Spacesuits

This paper describes the effort and accomplishments for developing flexible fabrics with high thermal conductivity (FFHTC) for spacesuits to improve thermal performance, lower weight and reduce complexity. Commercial and additional space exploration applications that require substantial performance enhancements in removal and transport of heat away from equipment as well as from the human body can benefit from this technology. Improvements in thermal conductivity were achieved through the use of modified polymers containing thermally conductive additives. The objective of the FFHTC effort is to significantly improve the thermal conductivity of the liquid cooled ventilation garment by improving the thermal conductivity of the subcomponents (i.e., fabric and plastic tubes). This paper presents the initial system modeling studies, including a detailed liquid cooling garment model incorporated into the Wissler human thermal regulatory model, to quantify the necessary improvements in thermal conductivity and garment geometries needed to affect system performance. In addition, preliminary results of thermal conductivity improvements of the polymer components of the liquid cooled ventilation garment are presented. By improving thermal garment performance, major technology drivers will be addressed for lightweight, high thermal conductivity, flexible materials for spacesuits that are strategic technical challenges of the Exploration

Lanthanide(III) Oxide Nanocomposites with Hexafluoroisopropylidine-based Polyimides

In the mid-1960’s Coe (1) and Rogers (2) developed the synthetic route to 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) for use in the preparation of hexafluoroisopropylidene-containing aromatic polyimides. Rogers (2,3) reported the synthesis of 6FDA-based polyimides with diamines including 2,2-bis(4-aminophenyl)hexafluoropropane (4,4 ́-6F), 4,4 ́-oxydianiline (ODA), and l,3-bis(4-aminophen-oxy)benzene (1,3(4)-APB). Early interest in 6F-containing polyimides appears to have centered on the fact that the flexible, non-polarizable, and spatially bulky isopropylidene group lowers the effective symmetry of the dianhydride unit due to the availability