Chuanli Qin

Immobilized polyazomethines containing triphenylamine groups on ITO: synthesis and acidochromic, electrochemical, electrochromic and photoelectronic properties

A new series of polyazomethines (PAMs) containing triphenylamine (TPA) as easily-oxidized units were synthesized as highly soluble materials with electrochromism. 2,5-Bis(hexyloxy)terephthaldehyde and four different kinds of diamine were condensed to construct the PAMs under benign conditions with n values of 21 700–25 400 g mol−1. The color of the PAM solution changed reversibly between light yellow and navy blue with the increase and decrease of pH. The PAMs with a high number of alkyl groups, which could dissolve facilely in many common organic solvents, were grafted onto ITO through siloxane linkages to be cast into tough films. During the electrochemical reoxidation process, the films showed color switching with high coloration efficiency. The HOMO and LUMO levels were determined via cyclic voltammograms combined with the UV-visible spectrum as −5.14 to −4.79 eV and −2.81 to −2.54 eV, respectively, which can be utilized in the hole transporting layer in organic light-emitting diodes (OLEDs) or solar cell (SC) devices.

Fabrication and photoluminescence of hyperbranched silicon nanowire networks on silicon substrates by laser-induced forward transfer

The structure and photoluminescent properties of films obtained by modified laser-induced forward transfer of silicon are presented. Strong variations in structure with ambient gas composition are observed: in Ar, porous films of mutually agglomerated silicon nanoparticles are observed, while in air the films consist of a network of hyperbranched nanowires (SiHBNWs) whose diameter varies periodically along their length, and which are composed of crystalline silicon nanoparticles surrounded and interconnected by amorphous silicon oxide of varying stoichiometry. The mechanisms of formation of the structures are dwelt upon and explained in term of dynamics within the plume. For the SiHBNWs, the pioneering use of fluorescence imaging was employed to obtain evidence for the photoluminescence originating from the crystalline nanoparticles themselves, and origins of the emission bands are thus attributed to radiative recombination of excitons at the Si/SiO(2) interface accordingly.

Polyurethanes prepared from isocyanates containing triphenylamine derivatives: synthesis and optical, electrochemical, electrochromic and memory properties

Two novel series of triphenylamine (TPA)-containing aromatic polyurethanes (PUs) were synthesized via polymerization of N′,N′-bis(α-naphthyl)-N,N′-bis(4-phenylisocyanate) biphenyl (M1) and N,N′-diphenyl-N,N′-bis(4-phenylisocyanate) biphenyl (M2) with different dihydroxy compounds. The structures of the polymers were characterized by Fourier transform infrared (FT-IR) spectroscopy, hydrogen nuclear magnetic resonance (1H-NMR) and carbon nuclear magnetic resonance (13C-NMR); and the thermostability and morphology were studied by thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The molecular weights were measured to be from 1.02 × 104 to 1.31 × 104 by gel permeation chromatography (GPC). The polymers were coated onto indium tin oxide (ITO) and the electrochromic properties were investigated by using the ultraviolet visible (UV-vis) absorption spectra and cyclic voltammetry (CV). The energy gaps were in the range of 2.21–2.26 eV. The polymer films revealed good stability of the electrochromic characteristics by continuous cyclic scans, with the color changing from neutral yellowish to a blue doped form at applied potentials. Meanwhile, the PUs film exhibited non-volatile write-once-read-many-times (WORM) memory behavior in the device resulting from the non-isolated donor–acceptor (D–A).

Schiff bases containing triphenylamine and pyrrole units: synthesis and electrochromic, acidochromic properties

Five Schiff bases (SBs) containing pyrrole and different triphenylamine (TPA) moieties were synthesized and the structures were confirmed by infrared spectroscopy (IR) and the nuclear magnetic resonance (NMR) technique. SB1 exhibited intense fluorescence emission in contrast to SB2–SB5. The electrochemical behaviors of the SBs were investigated by the cyclic voltammetry (CV) technique. SB2–SB5 exhibited redox stability with one well-defined and reversible redox couple upon electrochemical oxidation. On the contrary, SB1 revealed two oxidation peaks and one reduction peak in the first CV curve, followed by four well-defined redox couples in the steady-state CV curves. Electrochromic behaviors of the SBs have been observed, accompanied with a new absorption peak appearing with obvious color change from pale yellow neutral form to red oxidation form. SB1–SB5 also displayed sensitive acidochromic behaviors, and a linear dependence of maximum absorption wavelength as a function of pH values has been observed which proved the SBs could be used as alternative pH sensors in the given range.

Blue Light Emission from Pulsed Laser Ablated Polystyrene

Thus far, pulsed laser ablation has been widely applied to the surface modification of polymers, but no work has been done for fluorescence performance of polystyrene ablated by pulsed laser. In this paper, a 1064 nm pulsed laser was used to ablate polystyrene. Compared to non-ablated polystyrene, the ablated polystyrene gave off obvious blue light under UV lamp irradiation. The morphology and structure of ablated and non-ablated polystyrene were studied by Fluorescence spectroscopy and IR. The results showed that the maximal emission wavelength of ablated polystyrene was 403 nm, which showed that blue light emission occurred. Because of ablation the surface chemical structure of polystyrene was changed and new C=C existed in the surface of ablated polystyrene. And the photoluminescent material was dissolvable, not cross-linked.

Blue light emission from pulsed laser ablated polyethylene

The 1064 nm pulsed laser was used to ablate polyethylene (PE) at different power. Compared with unmodified PE, the ablated polyethylene (PE) gave off obvious blue light under UV lamp irradiation. The morphology and tre structure of ablated and unmodified PE were studied by scanning electron microscope, fluorescence spectroscopy and raman spectroscopy. the results showed that double bonds existed in the ablated PE which resulted in obvious blue emission of ablated PE and the intensity of the laser had great influence on the physical properties and chemical structure of the PE surface.

Magnetic porous graphene/multi-walled carbon nanotube beads from microfluidics: a flexible and robust oil/water separation material

In this paper, magnetic porous graphene/multi-walled carbon nanotube beads (MPGCBs) were fabricated by a modified capillary microfluidic device. Polystyrene (PS) microspheres not only served as the hard templates to form uniform macropores, but were also beneficial for keeping the stability of spherical architecture. In the process of solidification, both graphene oxide (GO) and acidified multi-walled carbon nanotubes (aMWCNTs) enriched with carboxyl functional groups can form stable and uniform dispersion in the droplets. After the calcination treatment, the composite beads had excellent water resistance and robust mechanical properties. Moreover, due to the addition of the Fe3O4 nanoparticles, the beads also possessed the advantage of flexible operation, which can facilitate oriented movement and recycling of the absorbents, and promoted the collection and recovery of the useful pollutants. These multi-functional MPGCBs with interconnected macroporous structures showed high absorption capacity (up to 8–25 times their own weight) for various kinds of oils and organic solvents, relatively high separation efficiency and long-term recycle stability in the oil/water mixture separation process.

The influence of urea on composition, microstructure and electrochemical properties of nitrogen-enriched carbon based on polyvinylpyrrolidone/melamine formaldehyde resin

Purpose – The purpose of this paper is to develop porous nitrogen-enriched carbon (NC-U) with high nitrogen concentration and high specific capacitance (Cpe) as the electrode material for supercapacitors. Design/methodology/approach – NC-U was obtained by carbonization of polyvinylpyrrolidone/melamine formaldehyde resin (PVP/MF) with different contents of urea. In comparison, NC-K was also prepared by the KOH activation method. A series of asymmetric supercapacitors with NC as a negative electrode was assembled. The composition, microstructure and electrochemical properties of NC and their supercapacitors were studied. Findings – The results show that NC-U shows irregular particles with a porous honeycomb structure. High Cpe was obtained for urea-treated NC-U because of the improvement of nitrogen, conductivity and specific surface area (S BET ). NC-U50 with 13.15 per cent at nitrogen has the highest Cpe of 148.53 F/g because of the highest concentration of N-6 and N-5. NC-K with higher S BET has lower Cp...

The Influence of Reaction Kinetics on Polyurethane/Vinyl Ester Resin Interpenetrating Polymer Networks

Polyurethane/poly(vinyl ester resin)(butyl methacrylate) Interpenetrating Polymer Network (PU/VER(BMA) IPN) materials were synthesised at room temperature by polymerising butyl methacrylate as a comonomer with simultaneous interpenetration. The curing process of these IPNs was dynamically traced and semi-quantitatively analysed by Fourier transform infrared spectroscopy (FT-IR) and the kinetics of their formation with different PU catalysts and VER initiators was studied. The results showed that when the amounts of stannous octoate and BPO respectively were 0.5wt.% of PU and 0.67wt.% of VER, the reaction rates of the monomers were close, the conversions of the monomers were high and these amounts were optimised. The influence of the kinetics on the microstructure and damping properties of the IPNs was detected by Transmission Electron Microscopy (TEM) and by Dynamic Mechanical Analysis (DMA). The results showed that with the appropriate amount of the polyurethane catalyst stannous octoate and VER initiator BPO, the PU/VER(BMA) IPN showed a multiphase microstructure containing some finer phase domains having nanometre domain sizes, together with good damping properties (a broad damping plateau and high tanδ). When the amount of stannous octoate or BPO was increased or decreased, the IPNs presented an unfavourable microstructure and poor damping properties. The relationship between the kinetics, microstructure and damping properties was analysed further.