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CHARGED POLYELECTROLYTE BRUSHES FOR VOLTAGE-CONTROLLED GATING OF NANOFLUIDIC CHANNEL: MOLECULAR DYNAMICS SIMULATION

Abstract Details

2010, Master of Science, University of Akron, Mechanical Engineering.
Polyelectrolyte brushes, ionizable polymers with one end tethered on surface, have received considerable interest in research recently due to their responsive behavior to the environments, which have wide applications in drug delivery, nanofuidics, colloid, surface science and nanotechnology. Polyelectrolyte brushes can response to external stimuli such as pH value, ionic strength of bulk solution, temperature, light and external electric field. Numerous works have been done by experiments, simulations and theory analysis on responsive-brushes. Among all the external stimuli, electric fields represent a favorite approach to induce motion and deformation of polyelectrolytes brushes because they can be applied much faster than other stimuli. An external electrical field can induce extension-collapse transition of charged polymer brushes from equilibrium; this transition is expected to result in changes in flow rate or permeability, and conductance/impedance of a nanochannel. Additionally, electric field controlled brushes can be relatively easier to be integrated with MEMS (Micro-Electro-Mechanical Systems) and NEMS (Nano-Electro-Mechanical Systems) devices. Therefore the use of electric-field responsive polymer brushes could lead to the development of advanced gating systems for various applications such as drug delivery, biosensors, data storage, smart valves, and nanoelectronic devices. This thesis presents systematic molecular dynamic simulations on responsive behavior of charged polyelectrolyte brushes to external electric field and their application as a nanovalve in nanofluidic channels. First, brush density profile and mean height were investigated under varied electric field strength, charge fraction, and grafted densities without solvent particles. Under weak and strong electric field, polymer brushes were partially and fully stretched brushes respectively. The dynamic responsive behavior of the polymer brushes to applied AC electric field was studied. The response frequency can reach a few hundred MHz. Grafted density and charge fraction also affect the response of brushes. Polymer brushes with low grafting density and low charge fraction displayed a large change in average height under external electric fields. Based on the above parametric study, the flow gating behavior of charged polyelectrolyte brushes in a nanofluidic channel was studied using molecular dynamic simulation. Results show that under an electrical filed, polyelectrolyte brushes act as functional gates through extension/collapse transition in water based solvent. By switching the direction of external electric field, the polyelectrolyte brushes can close or open the nanochannel. Furthermore, the flow rate can be regulated by adjusting the strength of the electric field. This nanovalve is simple in structure and is fully controlled by electrical signals, having potential for many applications.
Jiang Zhe, Dr. (Advisor)
Zhenhai Xia, PhD (Advisor)
Guoxiang Wang, PhD (Committee Member)
93 p.

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Citations

  • Ouyang, H. (2010). CHARGED POLYELECTROLYTE BRUSHES FOR VOLTAGE-CONTROLLED GATING OF NANOFLUIDIC CHANNEL: MOLECULAR DYNAMICS SIMULATION [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1271133521

    APA Style (7th edition)

  • Ouyang, Hui. CHARGED POLYELECTROLYTE BRUSHES FOR VOLTAGE-CONTROLLED GATING OF NANOFLUIDIC CHANNEL: MOLECULAR DYNAMICS SIMULATION. 2010. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1271133521.

    MLA Style (8th edition)

  • Ouyang, Hui. "CHARGED POLYELECTROLYTE BRUSHES FOR VOLTAGE-CONTROLLED GATING OF NANOFLUIDIC CHANNEL: MOLECULAR DYNAMICS SIMULATION." Master's thesis, University of Akron, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=akron1271133521

    Chicago Manual of Style (17th edition)