Qiguang Yang

Bio: Qiguang Yang is an academic researcher from Jilin University. The author has contributed to research in topics: Azobenzene & Photon upconversion. The author has an hindex of 6, co-authored 9 publications receiving 125 citations.

Study on correlation of morphology of electrospun products of polyacrylamide with ultrahigh molecular weight

Abstract: Polyacrylamide (PAAm) with ultrahigh molecular weight of 9 × 106 g/mol has been processed by means of electrospinning, to afford products with a variety of morphologies, including polymer colloids, beaded fibers, smooth fibers, and ribbons. These morphologies can be controlled by a minute change of solution concentration in a small concentration range (0.3–3.0 wt %), because of the high molecular weight of the polymer. Under our experimental conditions, no electrospun product was obtained at the concentrations below 0.3 wt %. Beaded fibers and smooth fibers formed at the concentrations between 0.3 and 0.7 wt %. At concentrations between 0.7 and 2.0 wt %, smooth fibers and ribbons coexisted. At concentrations above 2.0 wt %, ribbons were the only product. Special morphologies such as triangular beads, helical fibers, and zigzag ribbons were also observed. With a lower molecular weight PAAm, branched fibers were found in the product. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2190–2195, 2005

Polarized-light-controlled holographic recording in an azobenzene-doped polymer film

Abstract: A new polarized-light-controlled holographic recording based on the optical enhancement/restraint of self-diffraction has been demonstrated in an azobenzene-doped polymer film. It is found that a continuous variation of the polarization status as well as of the intensity of the pumping light results in a continuous variation of self-diffraction efficiency. The mechanism originates from the photo-induced anisotropy and polarization-dependent absorption. Both positive and negative replicas of an incident image were presented in real time by means of this incoherent–coherent optical conversion technique.

Low-power phase conjugation in push–pull azobenzene compounds

Abstract: Push–pull azobenzene compounds were synthesized by the diazocoupling reaction, and low-power phase conjugation of azobenzene-compound-doped poly(methyl methacrylate) films was studied with a He–Ne laser at 632.8 nm. It is shown that this kind of polymer has appreciable third-order optical nonlinearity, with a χ(3) of approximately 10−4 esu in the tail of absorption.

Optically controlled image storage in azobenzene liquid-crystalline polymer films

Abstract: We report on optically controlled image storage based on photo-induced alignment in azobenzene liquid-crystalline polymer films. Measurements reveal that the polymer film possesses photo-induced birefringence of large magnitude and the characteristic of long-term optical storage. The photo-induced alignment process is used for storing images. The stored image is read from the film placed between two crossed polarizers. It is demonstrated clearly that the alignment of the azo chromophores as well as the stored image can be easily controlled by choosing the appropriate polarization of the irradiating light or by rotating the film.

Multiphoton Absorbing Materials : Molecular Designs, Characterizations, and Applications

Abstract: 4. Survey of Novel Multiphoton Active Materials 1257 4.1. Multiphoton Absorbing Systems 1257 4.2. Organic Molecules 1257 4.3. Organic Liquids and Liquid Crystals 1259 4.4. Conjugated Polymers 1259 4.4.1. Polydiacetylenes 1261 4.4.2. Polyphenylenevinylenes (PPVs) 1261 4.4.3. Polythiophenes 1263 4.4.4. Other Conjugated Polymers 1265 4.4.5. Dendrimers 1265 4.4.6. Hyperbranched Polymers 1267 4.5. Fullerenes 1267 4.6. Coordination and Organometallic Compounds 1271 4.6.1. Metal Dithiolenes 1271 4.6.2. Pyridine-Based Multidentate Ligands 1272 4.6.3. Other Transition-Metal Complexes 1273 4.6.4. Lanthanide Complexes 1275 4.6.5. Ferrocene Derivatives 1275 4.6.6. Alkynylruthenium Complexes 1279 4.6.7. Platinum Acetylides 1279 4.7. Porphyrins and Metallophophyrins 1279 4.8. Nanoparticles 1281 4.9. Biomolecules and Derivatives 1282 5. Nonlinear Optical Characterizations of Multiphoton Active Materials 1282

One-Dimensional Composite Nanomaterials: Synthesis by Electrospinning and Their Applications

Abstract: This Review provides an overview of the synthesis of one-dimensional (1D) composite nanomaterials by electrospinning and their applications. After a brief description of the development of the electrospinning technique, the transformation of an inorganic nanocomponent or polymer into another kind of polymer or inorganic matrix is discussed in terms of the electrospinning process, including the direct-dispersed method, gas-solid reaction, in situ photoreduction, sol-gel method, emulsion electrospinning method, solvent evaporation, and coaxial electrospinning. In addition, various applications of such 1D composite nanomaterials are highlighted in terms of electronic and optical nanodevices, chemical and biological sensors, catalysis and electrocatalysis, superhydrophobic surfaces, environment, energy, and biomedical fields. An increasing number of investigations show that electrospinning has been not only a focus of academic study in the laboratory but is also being applied in a great many technological fields.

Effects of Working Parameters on Electrospinning

Abstract: Working parameters are very important to understand not only the nature of electrospinning but also the conversion of polymer solutions into nanofibers through electrospinning. Those parameters can be broadly divided into three parts such as solution parameters, process parameters, and ambient parameters. Each of those parameters can affect the fibers morphologies and by proper control of those parameters we can fabricate electrospun fibers with desired morphologies and diameters. In this chapter, we will present a concise introduction of those parameters and their influence on fiber properties.

Thermally induced phase separation and electrospinning methods for emerging membrane applications: A review

Abstract: In this review, thermally induced phase separation (TIPS) and electrospinning methods for preparation of fluoropolymer membranes are assessed, particularly for the polyvinylidene fluoride (PVDF) and polyethylene chlorotrifluoroethylene membranes. This review focuses on controlling the membrane morphology from the thermodynamic and kinetic perspectives to understand the relationship between the membrane morphology and fabrication parameters. In addition, the current status of the nonsolvent induced phase separation (NIPS) method and the combined NIPS-TIPS (N-TIPS) method, which is a new emerging fabrication method, are discussed. The past literature data are compiled and an upperbound curve (permeability vs. tensile strength) is proposed for the TIPS-prepared PVDF membranes. Furthermore, the key parameters that control and determine the membrane morphology when using the electrospinning method are reviewed. Exploiting the unique advantages of the electrospinning method, our current understanding in controlling and fine-tuning the PVDF crystal polymorphism (i.e., β-phase) is critically assessed. © 2015 American Institute of Chemical Engineers AIChE J, 62: 461–490, 2016