Montmorillonite/polyimide (3,3‘,4,4‘-benzophenone tetracarboxylic dianhydride-4,4‘-oxydianiline, BTDA-ODA) nanocomposites displaying different morphological, thermal, and mechanical characteristics were synthesized by involving mono-, di-, and trifunctional group swelling-agent-modified montmorillonite and poly(amic acid). It was found that the dispersion of silicate layers in BTDA-ODA shifted from intercalated to exfoliated structures when the number of functional groups of the swelling agent increased to three as evidenced from X-ray diffraction and transmission electron microscopy studies. The improved morphology of the nanocomposites resulted in their enhanced mechanical and thermal properties. In particular, a 70% increase in Young's modulus, a 50% increase in the maximum stress, and a 30% reduction in the coefficients of thermal expansion for the case of BTDA-ODA nanocomposites containing 5 wt % trifunctional group swelling-agent-modified montmorillonite as compared to that of pure BTDA-ODA.

Structured silicates/fluorinated polyimide nanocomposites display excellent water‐absorption retardation behavior. This leads to lower leakage‐current densities and lower dielectric constants under higher humidity conditions than those of the pristine fluorinated polyimides. Part of the chemical structure of the layered silicate used in this work is shown in the Figure.

Two new triptycene‐containing bis(ether amine)s, 1,4‐bis(4‐aminophenoxy)triptycene (4) and 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)triptycene (6), were synthesized, respectively, from the nucleophilic chloro‐displacement reactions of p‐chloronitrobenzene and 2‐chloro‐5‐nitrobenzotrifluoride with 1,4‐dihydroxytriptycene in the presence of potassium carbonate, followed by palladium‐catalyzed hydrazine reduction of the dinitro intermediates. The bis(ether amine)s were polymerized with six commercially available aromatic tetracarboxylic dianhydrides to obtain two series of novel triptycene‐based polyimides 8a–f and 9a–f by using a conventional two‐step synthetic method via thermal and chemical imidizations. All the resulting polyimides exhibited high enough molecular weights to permit the casting of flexible and strong films with good mechanical properties. Incorporation of trifluoromethyl groups in the polyimide backbones improves their solubility and decreases their dielectric constants. The fluorinated polyimides 9d and 9f derived from diamine 6 with 4,4′‐oxydiphthalic anhydride and 2,2‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), respectively, could afford almost colorless thin films. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

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A novel electrochromic device (ECD) based on an electroactive ambipolar system was constructed and designed through an absorption-complementary approach. The system consisted of electroactive polyamides (PAs) with N,N,N′,N′-tetraphenyl-pphenylenediamine (TPPA) and tetraphenylbenzidine (TPB) units in the backbone and heptyl viologen (HV) in the supporting electrolyte. Each of the electrochromic materials (ECMs), including TPPA-PA, TPB-PA and HV, provided one of the three primary colors that merged into a black color. Because of the suitable counter electrode materials used in this study, the overall operating voltage was effectively reduced; thus, the electrochemical stability and lifetime of the ECD were greatly enhanced. Furthermore, the whole system was completely transparent in its neutral or bleaching state, and the transmittance was reduced to only 6% in the colored state in both the visible and near-infrared (NIR) regions. The ECD demonstrated a high L* change (ΔL*) of 81 and a significant transmittance change (ΔT) of 60% in the visible region. Thus, through the excellent combination of the electrochromic and ambipolar characteristics of the system, a genuine 'highly transparent to truly black' ECD was successfully fabricated, implying the great potential of this device as a shutter in transparent displays and related devices.