Multicolored electrochromic materials have attracted intense attentions due to their diverse smart applications. In this work, we demonstrate a facile strategy to realize multistage visible/near-infrared (vis/NIR) electrochromism by designing and synthesizing two kinds of novel hyperbranched polyimides (HBPIs) from a novel triamine as an A3 monomer and two dianhydrides as B2 monomers. The resulting HBPIs exhibit excellent solubility and thermostability. Cyclic voltammograms of the HBPIs films reveal four reversible redox couples along with five color conversions (colorless-yellow-red-indigo-black). Furthermore, the HBPIs exhibit superb electrochromic performances including continuous modulation over the entire visible region, short response time, high optical contrast, high coloration efficiency, excellent switching stability and long-term optical memory. Accordingly, these HBPIs are promising materials in the applications of electrochromism and even endowing difunctionality combining with supercapacitance.Novel hyperbranched polyimides with star-shaped triphenylamine were synthesized, which exhibited multistage visible/near-infrared electrochromic and supercapacitive properties.Download high-res image (198KB)Download full-size image

To investigate the structure–property relationships of polyimides containing pyrimidine or pyridine moieties, two diamine monomers, 2-phenyl-4,6-bis(4-aminophenoxy)pyrimidine and 1,3-bis(5-amino-2-pyridinoxy)benzene, were designed and synthesized. The diamines reacted with different commercially available aromatic dianhydrides to yield a series of heterocyclic polyimides via a classical two-step polymerization method. The polyimides, PI-1 and PI-6, exhibited excellent solubility in strong polar solvents, such as N,N-dimethylacetamide, N,N-dimethylformamide and N-methyl-2-pyrrolidone. The flexible, strong and transparent polyimide films were formed with UV-visible absorption cut-off wavelengths at 344–399 nm. Glass transition temperatures (Tg) of the polyimides PI-(1–6), derived from PBAPD and BADB with dianhydrides, in the range of 212–260 °C were obtained by DSC, and the temperatures for 5% wt loss of the polyimides in nitrogen and air atmospheres were obtained from TGA in the range of 430–503 °C and 422–465 °C, respectively. Moreover, the polyimide films showed a low moisture absorption of 0.18–1.38% and outstanding mechanical properties with tensile strengths of 81–111 MPa, an elongation at break of 4.3–8.7%, and a tensile modulus of 1.3–2.4 GPa. The coefficients of thermal expansion (CTEs) of the polyimides ranged from 28 to 62 ppm °C−1.

Polyimide based hollow magnetic nanospheres were successfully prepared by combining the situ and template methods together. The morphology, composition, microstructure, thermal property and the magnetic property of the samples were characterized by scanning electron microscopy (SEM), scanning transmission electron microscopy (TEM), infrared spectroscopy (IR), thermo gravimetric analyzer (TGA) and vibrating sample magnetometer (VSM), respectively. The results showed that the PI magnetic hollow nanospheres(PI-MHNS) exhibited hollow structure and uniform size with an average diameter of 500 nm. The 5% weight lost temperature of the PI-MHNS was at about 400 °C and the saturation magnetization of the samples was 2.87 emu/g. All of the above properties meant that the PI-MHNS would have potential applications in many fields.Highlights► Combining the situ and template methods is simpler to synthesis the products. ► The properties of the polyimide and the hollow structure can be retained. ► The magnetic particles are dispersed in a uniform manner. ► The resulted products are high-temperature resistance. ► The resulted products have a certain extent magnetic response.

In this communication, uniform and size-controllable PI composite hollow spheres were fabricated by means of in situ favorable adsorption within sulfonated polystyrene hollow sphere templates. It was calculated that more than 33 wt.% polyimides existed on the resulting composite hollow spheres, which endued them with excellent high-temperature resistance. The high carbon remaining and favorable shape reservation of the PI-based composite hollow spheres made them promising precursors of carbon hollow spheres.