The development of polyimides (PIs) with a superheat resistance and a high thermal dimensional stability is required urgently for application in the rapidly growing area of flexible-display substrates. Based on an enhanced intermolecular interaction, 2,2′-p-phenylenebis­(5-amino­benzimidazole) (DP) that contains bis-benzimidazole was synthesized, and two series of its copolyimides (PI-a and PI-b) were prepared by copolycondensation with 5-amino-2-(4-aminobenzene)­benzimidazole (PABZ) and 5-amino-2-(3-aminobenzene)­benzimidazole (i-PABZ), respectively. The high density and packing coefficient of the resulting PIs caused by the strong intermolecular interaction from the hydrogen bonds and the charge-transfer complex provided the PI films with a very high glass-transition temperature (T g > 450 °C) and an extremely low coefficient of thermal expansion (CTE) below 10 ppm/K for PI-a. Such good thermal properties expand their application as high thermostable materials. Furthermore, the PI-b had a higher T g than PI-a, whereas the latter had lower CTE values because of the configuration difference of their polymer chains. These data indicate that the resultant thermostable copolyimides have potential application as a flexible-display substrate and provide a feasible method to improve the thermal properties by incorporating bis-benzimidazole moieties.

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COMMUNICATIONthis system for the fabrication of metamaterials that have useful metallic photonic behaviors such as strong localized surface plasmon resonance (LSPR), and the tuning range of its PBG was also limited (560-640 nm).In this work, we demonstrate a simple strategy for rapid and scalable fabrication of well-ordered metallodielectric 1D PhCs using amphiphilic brush BCPs as the templates and H-bonding as a driving force for the selective incorporation of gold NPs into hydrophilic domains (see Figure 1 ). We express the concentrations of the gold NPs as the weight percentage (wt%) of the nanocomposites based on the mass of the NP core and ligand shell, while the wt% of the NP core (Au%) was determined using the thermogravimetric analysis (TGA) of the composite and refl ects the Au metal content of the composite. The content of the gold NPs of ≈2 nm in a core diameter was up to 67.2 wt% (Au% = 48.4 wt%), corresponding to 80.4 wt% of the gold NPs (Au% = 58.1 wt%) in the hydrophilic domain. By varying the gold NP loading quantity or the molecular weight of the brush BCP, highly ordered metallodielectric structures with the domain spacing controlled from 120 to 260 nm were readily created resulting in widely tunable PBGs from the visible to near-IR region (458-1010 nm). Moreover, the PBG is also tunable via thermally induced ripening of the NPs, which infl uences their size as well as their distribution (see Figure 1 ). A network structure of gold NPs with diameters greater than 10 nm was formed after thermal annealing leading to greatly increased conductivity and higher effective refractive index of the gold NP layer. The optical properties of the metallodielectric PhCs were signifi cantly infl uenced by the network structure of gold NPs, which is tunable simply through the variation of annealing time. Numerical modeling using transfer matrix methods was employed to quantify the optical characteristics infl uenced by the effective conductivity of the gold NP network and showed a good agreement with the experimental results.Recently, chemists have made a signifi cant progress in design and synthesis of brush BCPs which show substantially reduced polymer chain entanglements relative to their linear analogues. This enables rapid self-assembly to yield nanostructures with domain sizes on the order of several hundreds of nanometers. [19][20][21][22][23][24][25] Introducing metal NPs into the large microdomains of phase-separated brush BCPs is of great interest from both fundamental research and application viewpoints. In our work, the brush BCPs were well-defi ned (polynorbornene-g -polystyrene)-b -(polynorbornene-g -poly(ethylene oxide)) block copolymers ((PNB-PS 3.5k ) n -b -(PNB-PEO 2k ) m ) synthesized by sequential ring opening metathesis polymerization (ROMP) (see the Supporting Information for details). The molecular weight of the Photonic crystals (PhCs) prepared via the self-assembly of block copolymers (BCPs) offer new opportunities for simple fabrication of fl exible photonic devices or coatings in an in...

We report that an exceptionally large volume of highly ordered arrays (single grains) on the order of millimeters in scale can be rapidly created through a unique innate guiding mechanism of brush block copolymers (BBCPs). The grain volume is over 10(9) times larger than that of typical self-assembled linear BCPs (LBCPs). The use of strong interactions between nanoparticles (NPs) and BBCPs enables high loadings of functional materials, up to 76 wt % (46 vol %) in the target domain, while maintaining excellent long-range order. Overall, this work provides a simple method to precisely control the spatial orientation of functionalities at nanometer length scales over macroscopic volumes, thereby enabling the production of hybrid materials for many important applications.

A new strategy based on ionic self-assembly technology was provided for design of photosensitive material as liquid crystals (LC) alignment layer. The complex material was constructed by the coupling of poly-(ionic liquid) and photosensitive unit azobenzene dye methyl orange. The structure, phase behavior and photoresponse were examined by a variety of techniques including FTIR, NMR, thermal analysis, polarized optical microscopy, X-ray diffraction, small-angle X-ray scattering, and birefringence measurements. Highly ordered lamellar nanostructure and photosensitive character were confirmed. Under the irradiation of pulsed UV laser with certain fluences, a pronounced optical anisotropic surface with the preferred direction perpendicular to the pulsed polarization or regular periodic grooves microstructure surface parallel to the pulsed polarization was obtained. The anisotropic surface of oriented molecular chain or topography was demonstrated to result in the alignment of LC by the optical transmittance plot and polarizing microscopy images of LC cells with different rotation angles.