Magnetically Assembled Multisegmented Nanowires and Their Applications

Here we report a cost effective and versatile way of synthesizing and assembling multi‐functional (e.g., gold‐polypyrrole‐nickel‐gold) nanowires. Multisegmented nanowires were synthesized using electrodeposition method for precise control over segment dimensions for proper expression of material functionality. The nanowires were integrated on microfabricated electrodes using magnetic dipole interactions between the ferromagnetic segment in the nanowire and the ferromagnetic electrodes. The electrical properties of multisegmented nanowires showed semiconducting behavior with the activation energy of ca. 0.27 eV for the conducting polymer segment of the nanowire. These nanowire devices showed response towards light and exposure to ammonia, demonstrating their potential use as photonic device and gas sensor, respectively.     

Chiral separation of amides of amino acid on a (S)‐N‐(3,5‐dinitrobenzoyl)leucine‐N‐phenyl‐N‐propylamide‐bonded silica using nonaqueous capillary electrochromatography

(S)‐N‐(3,5‐dinitrobenzoyl)leucine‐N‐phenyl‐N‐propylamine‐bonded silica was used as a chiral stationary phase for separation of a set of racemic π‐acidic and π‐basic α‐amino acid amides in electrolyteless ACN‐water eluents by CEC in the RP and polar organic (PO) modes. The effect of the amount of water in the ACN‐water eluent on chiral separation was examined. As water is added to ACN, retention was shortened but resolution and selectivity deteriorated severely. Retention, enantioselectivity, and resolution factors obtained in 100% ACN were compared with those in an n‐hexane‐isopropanol eluent with a small amount of water by normal phase (NP) CEC. Much shorter retention times with comparable enantioselectivities were observed with 100% ACN, demonstrating the advantage of separation on (S)‐N‐(DNB)leucine‐N‐phenyl‐N‐propylamine‐bonded silica in PO‐CEC over NP‐CEC.     

Polyaniline Microspheres Consisting of Highly Crystallized Nanorods

The preparation of self‐assembled polyaniline (PANi) microspheres via facile interfacial oxidation polymerization of aniline in the presence of DL ‐tartaric acid dopant is reported. Compared with PANis reported in the literature, the PANi prepared in this study exhibits a nanorod‐bundle morphology with exceptionally high crystallinity. These nanorods or nanorod bundles can self‐assemble into microspheres with unique alignment. The chemistry, morphology, and crystal structure of DL ‐tartaric acid doped microspheres were studied using SEM, TEM, SAED, XRD, and FTIR.

     

Effect of Solubility Parameter of Polymer-Solvent Pair on Turbulent Drag Reduction

Polymer-induced turbulent drag reduction by adding a minute amount of high-molecular weight polyisobutylene (PIB) into two different organic solvents of n-heptane and xylene was examined using a rotating disk system. The dependence of drag reduction (DR) efficiency on various factors such as polymer molecular weight, polymer concentration (C), and solvent quality was examined. Based on the linear relationship between C and C/DR for different molecular weights of PIB, a universal curve was able to characterize a particular polymer/solvent family, independent of the molecular weight of polymer.     

Transparent Nonlinear Optical Polymers for All‐Optical Wavelength Converters in Optical Fiber Communications

After synthesizing two chromophores with imine, we prepared acrylic nonlinear optical (NLO) polymers that contained the chromophores for all‐optical wavelength converters in optical fiber communication. The polymers show high d₃₃, 35 pm · V⁻¹, at 1.55 μm (pumping beam), considering their low losses, −3.0 dB · cm⁻¹, at a wavelength of 0.785 μm (near second harmonic signal beam of the pumping beam). This result means that the polymers are good candidates for wavelength converters of an approximately 1.55 μm signal beam.

UV‐vis spectra of NLO chromophores and polymers.     

Synthesis and Dispersion Characteristics of Multi‐Walled Carbon Nanotube Composites with Poly(methyl methacrylate) Prepared by In‐Situ Bulk Polymerization

Multi‐walled carbon nanotubes (MWNT) purified by acidic solution were processed with PMMA via an in‐situ polymerization. Experimental evidences indicate the role of radical initiator (AIBN) and MWNT, showing increases of polymerization rate and MWNT diameter. Induced radicals on the MWNT by AIBN were found to trigger the grafting of PMMA. Moreover, the solvent cast film showed a better nanoscopic dispersion of MWNT and possibilities of CNT composites in engineering applications.

Fractured surface of multi‐walled carbon nanotube composite with PMMA prepared by in‐situ bulk polymerization.     

ESIPT-Inspired Dual-Mode Photoswitches with Fast Molecular Isomerization in the Solid State

Photoswitchable materials have attracted considerable attention in various fields. Developing excellent solid-state dual-mode photoswitches is an important but challenging task. Herein, we propose a new strategy to construct an excited-state intramolecular proton transfer (ESIPT) inspired photoswitch ( DiAH-pht ) that possesses aggregation-induced emission (AIE) features and displays a fast molecular isomerization process characterized by dual-mode behavior in the solid state. Mechanistic studies indicate that introduction of a bulky group can create a folded molecular conformation that provides adequate volume to facilitate photoisomerization and the enhanced ESIPT effect can boost the isomerization process. The feasibility of our strategy was further demonstrated by the activated photoisomerization performance of the Schiff base derivatives. Furthermore, DiAH-pht shows good performance in the fields of dual-mode information encryption and high-density data storage.