Yin Yang

Publications (3)5.25 Total impact

• Article: Fabrication of micro-nano structure nanofibers by solvent etching.

  Minghua Min, Xuefen Wang, Yin Yang, Zongyuan Liu, Zhe Zhou, Meifang Zhu, Yanmo Chen, Benjamin S Hsiao
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  ABSTRACT: Micro-Nano structure nanofibrous affinity membranes of poly(ether sulfones) (PES) blended with a functional polymer poly(ethyleneimine) (PEI) were fabricated by electrospinning technique followed by solvent etching in crosslinking solution. The surface SEM image of the water washed PES/PEI nanofibrous membrane confirmed that PEI was concentrated on the fiber surface. The nanofibrous PES/PEI membranes were crosslinked in a mixture of acetone and water with glutaraldehyde (crosslinking agent, GA), and the micro-nano structural surface of the nanofibrous membranes was created by solvent etching due to the solvation between PEI and the solvent water in the crosslinking solution during the crosslinking process. The influence of the component of the crosslinking bath on the mophology of the resulting PES/PEI nanofibers was investigated. It was found that the relatively uniform micro-nano spherules grew on the surface of the nanofibers when the content of water in crosslinking solution was more than 20 wt%, and the diameters of the spherules were in the range of 50-250 nm. The advantage of the micro-nano structrue for the heavy metal ions removal in wastwater has been demonstrated by taking a series of static adsorption experiments. It was found that the micro-nano structrue of PES/PEI nanofibrous membranes could bring high performance of adsorption capacity for heavy metal ions, indicating that the unique morphology could bring much more large surface area per unit mass and high effectivity for heavy metal ions removal from aqueous solutions.
  Journal of Nanoscience and Nanotechnology 08/2011; 11(8):6919-25. · 1.56 Impact Factor
• Article: Aligned and molecularly oriented semihollow ultrafine polymer fiber yarns by a facile method

  Kai Zhang, Xuefen Wang, Yin Yang, Lili Wang, Meifang Zhu, Benjamin S. Hsiao, Benjamin Chu
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  ABSTRACT: In this work, aligned and molecularly oriented bone-like PLLA semihollow fiber yarns were manufactured continuously from an optimized homogeneous polymer-solvent-nonsolvent system [PLLA, CH2Cl2, and dimethyl formamide (DMF)] by a single capillary electrospinning via self-bundling technique. Here, it should be emphasized that the self-bundling electrospinning technique, a very facile electrospinning technique with a grounded needle (which is to induce the self-bundling of polymer nanofibers at the beginning of electrospinning process), is used for the alignment and molecular orientation of the polymer fiber, and the take-up speed of the rotating drum for the electrospun fiber yarn collection is very low (0.5 m/s). PLLA can be dissolved in DMF and CH2Cl2 mixed solvent with different ratios. By varying the ratios of mixed solvent system, PLLA electrospun semihollow fiber with the porous inner structure and compact shell wall could be formed, the thickness of the shell and the size of inner pores could be adjusted. The results of polarized FTIR and wide angle X-ray diffraction investigations verified that as-prepared PLLA semihollow fiber yarns were well-aligned and molecularly oriented. Both the formation mechanism of semihollow fibers with core-shell structure and the orientation mechanism of polymer chains within the polymer fibers were all discussed. The as-prepared self-bundling electrospun PLLA fiber yarns possessed enhanced mechanical performance compared with the corresponding conventional electrospun PLLA fibrous nonwoven membranes. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1118–1125, 2010
  Journal of Polymer Science Part B Polymer Physics 05/2010; 48(10):1118 - 1125. · 1.53 Impact Factor
• Article: Bionic electrospun ultrafine fibrous poly(L-lactic acid) scaffolds with a multi-scale structure.

  Kai Zhang, Xuefen Wang, Dazheng Jing, Yin Yang, Meifang Zhu
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  ABSTRACT: Poly(L-lactic acid) (PLLA) tissue engineering scaffolds with porous inner structures of individual fibers and controllable architectures were successfully fabricated from the homogeneous polymer-solvent-nonsolvent system (PLLA, CH(2)Cl(2) and DMF) by a single capillary electrospinning with certain conductive patterned templates as fiber collectors. PLLA was dissolved in dimethylformamide (DMF) and methylene chloride (CH(2)Cl(2)) mixed solvent with different ratios. Semi-hollow fiber with porous inner structure and compact shell wall was formed by controlling the content of DMF in the mixed solvents. It is believed that the phase separation should be the key origin for the formation of this microstructure. In order to mimic the natural extracellular matrix (ECM) with a specific structure, conductive patterned collectors were designed and employed to manufacture PLLA ultrafine fibrous scaffolds with three-dimensional architectures. We believe these kinds of multi-scale biodegradable fibrous scaffolds with specific microstructure and macro-architectures could make the electrospun fibrous scaffold better mimic the natural extracellular matrix to satisfy tissue engineering.
  Biomedical Materials 06/2009; 4(3):035004. · 2.16 Impact Factor