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Microfluidics and Nanofluidics

, Volume 9, Issue 6, pp 1051–1062 | Cite as

Electroosmotic flow in a nanofluidic channel coated with neutral polymers

  • Qianqian CaoEmail author
  • Chuncheng Zuo
  • Lujuan Li
  • Yanhong Ma
  • Nan Li
Research Paper

Abstract

We use molecular dynamics simulations to investigate the control of electroosmotic flow by grafting polymers onto two parallel channel walls. The effects of the grafting density and the electric field strength on electroosmotic flow velocity, counterion distribution and conformational characteristics of grafted chains have been studied in detail for athermal, good, and poor solvent cases. The simulation results indicate that in the range of grafting densities investigated, increasing the grafting density induces a different change tendency of electroosmotic flow velocity for three different solvent qualities. These tendencies are demonstrated to be related to counterion distribution, polymer coverage, and interactions between monomers and solvent particles. It is found that counterions tend to move toward the interface between polymer layer and solvent as the grafting density increases. Especially in the poor solvent case, most of the counterions gather near the interface at high grafting densities. A similar behavior is also observed when enhancing the electric field strength at a fixed grafting density.

Keywords

Electroosmotic flow Polymer coating Molecular dynamics Solvent quality 

Notes

Acknowledgments

This study was supported by the National Natural Science Foundation of China (No.30770501).

References

  1. Adiga SP, Brenner DW (2005) Flow control through polymer-grafted smart nanofluidic channels: molecular dynamics simulations. Nano Lett 5:2509–2514CrossRefGoogle Scholar
  2. Alexander S (1977) Adsorption of chain molecules with a polar head a scaling description. J Phys (France) 38:983–987Google Scholar
  3. Binder K (2002) Scaling concepts for polymer brushes and their test with computer simulation. Eur Phys J E 9:293–298CrossRefGoogle Scholar
  4. Boroudjerdi H, Kim YW, Naji A, Netz RR, Schlagberger X, Serr A (2005) Statics and dynamics of strongly charged soft matter. Phys Rep 416:129–199CrossRefGoogle Scholar
  5. Chen CH, Lin H, Lele SK, Santiago JG (2005) Convective and absolute electrokinetic instability with conductivity gradients. J Fluid Mech 524:263–303zbMATHCrossRefGoogle Scholar
  6. Chremos A, Glynos E, Koutsos V, Camp PJ (2009) Adsorption and self-assembly of linear polymers on surfaces: a computer simulation study. Soft Matter 5:637–645CrossRefGoogle Scholar
  7. de Gennes PG (1980) Conformations of polymers attached to an interface. Macromolecules 13:1069–1075CrossRefGoogle Scholar
  8. Dimitrov DI, Milchev A, Binder K (2007) Polymer brushes in solvents of variable quality: molecular dynamics simulations using explicit solvent. J Chem Phys 127:084905CrossRefGoogle Scholar
  9. Doherty EAS, Berglund KD, Buchholz BA, Kourkine IV, Przybycien TM, Tilton RD, Barron AE (2002) Critical factors for high-performance physically adsorbed (dynamic) polymeric wall coatings for capillary electrophoresis of DNA. Electrophoresis 23:2766–2776CrossRefGoogle Scholar
  10. Español P, Warren P (1995) Statistical mechanics of dissipative particle dynamics. Europhys Lett 30:191–196CrossRefGoogle Scholar
  11. Gao YD, Wong TN, Yang C, Ooi KT (2005) Two-fluid electroosmotic flow in microchannels. J Colloid Interface Sci 284:306–314CrossRefGoogle Scholar
  12. Goujon F, Malfreyt P, Tildesley DJ (2009) Mesoscopic simulation of entangled polymer brushes under shear: compression and rheological properties. Macromolecules 42:4310–4318CrossRefGoogle Scholar
  13. Grest GS (1994) Grafted polymer brushes: a constant surface pressure molecular dynamics simulation. Macromolecules 27:418–426CrossRefGoogle Scholar
  14. Harden JL, Long D, Ajdari A (2001) Influence of end-grafted polyelectrolytes on electro-osmosis along charged surfaces. Langmuir 17:705–715CrossRefGoogle Scholar
  15. Hickey OA, Harden JL, Slater GW (2009) Molecular dynamics simulations of optimal dynamic uncharged polymer coatings for quenching electro-osmotic flow. Phys Rev Lett 102:108304CrossRefGoogle Scholar
  16. Hockney RW, Eastwood JW (1988) Computer simulation using particles. Adam Hilger, BristolzbMATHGoogle Scholar
  17. Hoogerbrugge PJ, Koelman JMVA (1992) Simulating microscopic hydrodynamic phenomena with dissipative particle dynamics. Europhys Lett 19:155–160CrossRefGoogle Scholar
  18. Hu Y, Werner C, Li D (2003) Electrokinetic transport through rough microchannels. Anal Chem 75:5747–5758CrossRefGoogle Scholar
  19. Irfachsyad D, Tildesley D, Malfreyt P (2002) Dissipative particle dynamics simulation of grafted polymer brushes under shear. Phys Chem Chem Phys 4:3008–3015CrossRefGoogle Scholar
  20. Jeon J, Dobrynin AV (2007) Necklace globule and counterion condensation. Macromolecules 40:7695–7706CrossRefGoogle Scholar
  21. Kreer T, Muser MH, Binder K, Klein J (2001) Frictional drag mechanisms between polymer-bearing surfaces. Langmuir 17:7804–7813CrossRefGoogle Scholar
  22. Kremer K, Grest GS (1990) Dynamics of entangled linear polymer melts: a molecular-dynamics simulation. J Chem Phys 92:5057–5086CrossRefGoogle Scholar
  23. Krishnamoorthy S, Feng J, Henry AC, Locascio LE, Hickman JJ, Sundaram S (2006) Simulation and experimental characterization of electroosmotic flow in surface modified channels. Microfluid Nanofluid 2:345–355CrossRefGoogle Scholar
  24. Lai P-Y, Binder K (1993) Grafted polymer layers under shear: a Monte Carlo simulation. J Chem Phys 98:2366–2375CrossRefGoogle Scholar
  25. Lee JSH, Li DQ (2006) Electroosmotic flow at a liquid-air interface. Microfluid Nanofluid 2:361–365CrossRefGoogle Scholar
  26. Miao L, Guo H, Zuckermann MJ (1996) Conformation of polymer brushes under shear: chain tilting and stretching. Macromolecules 29:2289–2297CrossRefGoogle Scholar
  27. Murat M, Grest GS (1989) Interaction between grafted polymeric brushes: a molecular-dynamics study. Phys Rev Lett 63:1074–1077CrossRefGoogle Scholar
  28. Pastorino C, Binder K, Kreer T, Muller M (2006) Static and dynamic properties of the interface between a polymer brush and a melt of identical chains. J Chem Phys 124:064902CrossRefGoogle Scholar
  29. Paumier G, Sudor J, Gue AM, Vinet F, Li M, Chabal YJ, Esteve A, Djafari-Rouhani M (2008) Nanoscale actuation of electrokinetic flows on thermoreversible surfaces. Electrophoresis 29:1245–1252CrossRefGoogle Scholar
  30. Peters GH, Tildesley DJ (1995) Computer simulation of the rheology of grafted chains under shear. Phys Rev E 52:1882–1890CrossRefGoogle Scholar
  31. Qiao R (2006) Control of electroosmotic flow by polymer coating: effects of the electrical double layer. Langmuir 22:7096–7100CrossRefGoogle Scholar
  32. Qiao R (2007) Effects of molecular level surface roughness on electroosmotic flow. Microfluid Nanofluid 3:33–38CrossRefMathSciNetGoogle Scholar
  33. Qiao R, He P (2007) Modulation of electroosmotic flow by neutral polymers. Langmuir 23:5810–5816CrossRefGoogle Scholar
  34. Rubinstein M, Colby RH (2003) Polymer physics. Oxford University Press, OxfordGoogle Scholar
  35. Squires TM, Quake SR (2005) Microfluidics: fluid physics at the nanoliter scale. Rev Mod Phys 77:977–1026CrossRefGoogle Scholar
  36. Stone HA, Stroock AD, Ajdari A (2004) Engineering flows in small devices: microfluidics toward a lab-on-a-chip. Annu Rev Fluid Mech 36:381–411CrossRefGoogle Scholar
  37. Tessier F, Slater GW (2006) Modulation of electroosmotic flow strength with end-grafted polymer chains. Macromolecules 39:1250–1260CrossRefGoogle Scholar
  38. Thompson PA, Robbins MO (1990) Shear flow near solids: epitaxial order and flow boundary conditions. Phys Rev A 41:6830–6837CrossRefGoogle Scholar
  39. Wong I, Ho CM (2009) Surface molecular property modifications for poly(dimethylsiloxane) (PDMS) based microfluidic devices. Microfluid Nanofluid 7:291–306CrossRefGoogle Scholar
  40. Wu DP, Qin JH, Lin BC (2007) Self-assembled epoxy-modified polymer coating on a poly(dimethylsiloxane) microchip for EOF inhibition and biopolymers separation. Lab Chip 7:1490–1496CrossRefGoogle Scholar
  41. Yang DY, Liu Y (2008) Numerical simulation of electroosmotic flow in microchannels with sinusoidal roughness. Colloids Surf A 328:28–33CrossRefGoogle Scholar
  42. Yeh IC, Berkowitz ML (1999) Ewald summation for systems with slab geometry. J Chem Phys 111:3155–3162CrossRefGoogle Scholar

Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Qianqian Cao
    • 1
    Email author
  • Chuncheng Zuo
    • 1
  • Lujuan Li
    • 1
  • Yanhong Ma
    • 1
  • Nan Li
    • 1
  1. 1.College of Mechanical Science and EngineeringJilin UniversityChangchunPeople’s Republic of China

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