Xuefeng Tang

University of Science and Technology of China, Luchow, Anhui Sheng, China

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Publications (2)3.37 Total impact

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    ABSTRACT: Mechanical and viscoelastic properties of polymer layers adsorbed on solid-liquid interfaces from solutions can be distinctly different from that of the corresponding polymers in bulk solution due to interaction of molecules with the interfaces. We have studied the mechanical and viscoelastic properties of polyethylene glycol (PEG) solution boundary layers using a quartz crystal resonator technique. The viscosity and shear moduli of the PEG solution boundary layers as a function of PEG concentration are determined from the resonant frequency shift and the dissipation broadening of the resonance of the quartz crystal. The results show that the viscosity and the shear modulus of a boundary layer increase with the PEG concentration in the solution. The increase depends on the molecular weight and the molecular configuration. For solutions with large PEG molecules the viscoelastic properties of the solution boundary layers are distinctly different from that of corresponding bulk solutions. These behaviors can be explained in terms of solid-like behaviors due to an increased concentration of PEGs next to the quartz crystal surface and the interactions between PEG polymers and the interfaces.
    No preview · Chapter · Jan 2013
  • Sheng Qin · Xuefeng Tang · Lifei Zhu · Yifeng Wei · Xianbin Du · Da-Ming Zhu
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    ABSTRACT: Viscoelastic behavior of a solution boundary layer at a solid-liquid interface could differ from that of bulk solution due to molecular adsorption at the interface. Such a property can be used as a characteristic signature to indicate the molecular adsorption at the interface. In this work, we systematically measured the viscoelastic properties of polyethylene glycol (PEG) solution boundary layers in contact with a gold surface using a quartz crystal resonator technique. The results show that viscosity and shear modulus of the PEG boundary layer increase with the PEG concentration in the solution; the increasing rate depends on the molecular weight. For relatively small PEG molecules, the viscoelastic property of the PEG solution boundary layer is almost indistinguishable from that of the bulk solution of the same concentration, indicating no adsorption at the interface. For larger PEG polymers (with molecular weights above a few thousands grams per mole), the viscoelastic property of the solution boundary layer differs distinctively from that of the corresponding bulk solution. The difference can be attributed to physisorption of PEG molecules on the Au surface, which alters the viscoelastic behaviors of the boundary layer. The results suggest that adsorption behaviors of macromolecules at a solid-liquid interface might be inferred from the changes of the viscoelastic properties of a solution boundary layer.
    No preview · Article · Jun 2012 · Journal of Colloid and Interface Science