Dataset Information

Thickness dependent effective viscosity of a polymer solution near an interface probed by a quartz crystal microbalance with dissipation method.

ABSTRACT: The solution viscosity near an interface, which affects the solution behavior and the molecular dynamics in the solution, differs from the bulk. This paper measured the effective viscosity of a dilute poly (ethylene glycol) (PEG) solution adjacent to a Au electrode using the quartz crystal microbalance with dissipation (QCM-D) technique. We evidenced that the effect of an adsorbed PEG layer can be ignored, and calculated the zero shear rate effective viscosity to remove attenuation of high shear frequency oscillations. By increasing the overtone n from 3 to 13, the thickness of the sensed polymer solution decreased from ~70 to 30?nm. The zero shear rate effective viscosity of the polymer solution and longest relaxation time of PEG chains within it decrease with increasing solution thickness. The change trends are independent of the relation between the apparent viscosity and shear frequency and the values of the involved parameter, suggesting that the polymer solution and polymer chains closer to a solid substrate have a greater effective viscosity and slower relaxation mode, respectively. This method can study the effect of an interface presence on behavior and phenomena relating to the effective viscosity of polymer solutions, including the dynamics of discrete polymer chains.

SUBMITTER: Fang J

PROVIDER: S-EPMC4329548 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Thickness dependent effective viscosity of a polymer solution near an interface probed by a quartz crystal microbalance with dissipation method.

Fang Jiajie J Zhu Tao T Sheng Jie J Jiang Zhongying Z Ma Yuqiang Y

Scientific reports 20150216

The solution viscosity near an interface, which affects the solution behavior and the molecular dynamics in the solution, differs from the bulk. This paper measured the effective viscosity of a dilute poly (ethylene glycol) (PEG) solution adjacent to a Au electrode using the quartz crystal microbalance with dissipation (QCM-D) technique. We evidenced that the effect of an adsorbed PEG layer can be ignored, and calculated the zero shear rate effective viscosity to remove attenuation of high shear ...[more]

PMID: 25684747

Similar Datasets

Project description:Biofouling of polymeric membranes is a severe problem in water desalination and treatment applications. A fundamental understanding of biofouling mechanisms is necessary to control biofouling and develop more efficient mitigation strategies. To shed light on the type of forces that govern the interactions between biofoulants and membranes, biofoulant-coated colloidal AFM probes were employed to investigate the biofouling mechanisms of two model biofoulants, BSA and HA, toward an array of polymer films commonly used in membrane synthesis, which included CA, PVC, PVDF, and PS. These experiments were combined with quartz crystal microbalance with dissipation monitoring (QCM-D) measurements. The Derjaguin, Landau, Verwey, and Overbeek (DLVO) and the extended-DLVO (XDLVO) theoretical models were applied to decouple the overall adhesion interactions between the biofoulants and the polymer films into their component interactions, i.e., electrostatic (El), Lifshitz-van der Waals (LW), and Lewis acid-base (AB) interactions. The XDLVO model was found to predict better the AFM colloidal probe adhesion data and the QCM-D adsorption behavior of BSA onto the polymer films than the DLVO model. The ranking of the polymer films' adhesion strengths and adsorption quantities was inversely proportional to their γ- values. Higher normalized adhesion forces were quantified for the BSA-coated colloidal probes with the polymer films than the HA-coated colloidal probes. Similarly, in QCM-D measurements, BSA was found to cause larger adsorption mass shifts, faster adsorption rates, and more condensed fouling layers than HA. A linear correlation (R2 = 0.96) was obtained between the adsorption standard free energy changes (ΔGads°) estimated for BSA from the equilibrium QCM-D adsorption experiments and the AFM normalized adhesion energies (WAFM/R) estimated for BSA from the AFM colloidal probe measurements. Eventually, an indirect approach was presented to calculate the surface energy components of biofoulants characterized by high porosities from Hansen dissolution tests to perform the DLVO/XDLVO analyses.

Project description:BackgroundThe presence of lignin normally affects enzymatic saccharification of lignocellulose detrimentally. However, positive effects of lignin on enzymatic hydrolysis have been recently reported. Enzyme-lignin interactions could be the key to reveal the underlying mechanism of their discrepant behaviors. In this study, to elucidate the positive effects of extractable lignin (EL) on enzymatic hydrolysis of ethanol organosolv-pretreated wood sawdust, two lignin fractions, EL and milled wood lignin (MWL), were isolated sequentially from pretreated substrates. Quartz crystal microbalance with dissipation (QCM-D) was then used to investigate the lignin aggregation effects on enzyme adsorption.ResultsWe found that both EL and MWL had a narrow molecular weight distribution. However, MWL had an obviously higher molecular weight than EL. This indicated that EL and MWL likely represent two distinct lignin fractions from ethanol organosolv-pretreated substrates. HSQC NMR analysis revealed that less β-O-4, β-β, and β-5 linkages and a higher S/G ratio was present in EL, as compared to MWL. QCM-D analysis showed that the enzyme adsorption on lignin was highly relevant to these lignin structural characteristics. An obviously lower maximum enzyme adsorption capacity was observed on EL films (152.63-168.09 ng/cm2) compared to MWL films (196.71-224.73 ng/cm2). Furthermore, enzyme desorption on lignin films was determined. A significantly lower irreversible enzyme adsorption was observed on EL (75.40 ng/cm2) compared to MWL (137.35 ng/cm2). More importantly, two reconstructed lignin films were designed to investigate lignin assembly on enzyme adsorption. The results indicated that the presence of EL reduced irreversible enzyme adsorption on the reconstructed lignin films by 39.2-45.0%.ConclusionsLignin structure determined the interaction between enzyme and lignins. A positive correlation was observed between molecular weight, the content of β-5 linkages, and enzyme adsorption on lignin. EL, which was more depolymerized and less condensed, had the lower enzyme adsorption of the two preparations tested. Additionally, the presence of EL reduced enzyme adsorption on reconstructed lignin films, perhaps through a mechanism involving the blocking of non-productive enzyme binding sites on the MWL. This could be the mechanism for the positive effects of EL on enzymatic hydrolysis.

Dataset Information

Thickness dependent effective viscosity of a polymer solution near an interface probed by a quartz crystal microbalance with dissipation method.

Publications

Thickness dependent effective viscosity of a polymer solution near an interface probed by a quartz crystal microbalance with dissipation method.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets