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Dynamics and Structure of Smectic Liquid Crystal Multilayers at the Air/Water Interface

Dynamics and Structure of Smectic Liquid Crystal Multilayers at the Air/Water Interface. P.Basnet * L.Zou * J.Wang * V.Beleva * A.Bernoff † J.Alexander ¤ J.A.Mann Jr. ‡ E.K.Mann*.

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Dynamics and Structure of Smectic Liquid Crystal Multilayers at the Air/Water Interface

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  1. Dynamics and Structure of Smectic Liquid Crystal Multilayers at the Air/Water Interface P.Basnet * L.Zou * J.Wang * V.Beleva * A.Bernoff † J.Alexander ¤ J.A.Mann Jr. ‡ E.K.Mann* * Dept. of Physics, Kent State University,Kent ,OH 44242, † Dept.of Mathematics, Harvey Mudd College, Claremont, CA 91711, ¤ Dept. of Mathematics, Case Western Reserve University, Cleveland OH 44106, ‡ Dept. of Chemical Eng., Case Western Reserve University, Cleveland OH 44106 1

  2. Goal: Characterize boundaries between domainswith line tension l [Ref] 8CB Molecule Water [Ref] M.N.G. de Mul, J.A. Mann Jr.- Langmuir(1994, 1998) 2

  3. Why interested? line tension - helps determine equilibrium size and shape distribution for domains, - helps determine dynamics and stability of such domains - At this time, cannot be either predicted or controlled, unlike surface tension - few systematic experimental studies exist. Previous work J. Lauger, C.R. Robertson, C.W. Frank, G.G. Fuller- Langmuir,12(1996) - estimated line tension for the lowest two layers, - found a factor of 10 difference 3

  4. Surface pressure-area isotherm for 8CB 1 3 2 2 [Ref] 1 3 [Ref] Xue, Jung, M.W. Kim- PRL (1992) M.N.G. de Mul & J. A. Mann Jr.- Langmuir (1994) M.N.G. de Mul & J. A. Mann Jr.- Langmuir (19980) 5

  5. Experimental Techniques for domain deformation Stagnation Point Fig. a Two dimensional, extensional flow generated by using four-roll-mill Stagnation Line Fig. b Parallel band cell for simple shear flow [Ref] Driving force: Line tension [Ref]G.G .Fuller- Current opinion in Colloid & Interface Science 1997 [Ref] 6

  6. Relaxation of deformed domain 7

  7. 10

  8. Reflectivity & Thickness of Domains Trilayer / molayer 1 multi layer / trilayer Several multilayers / trilayer 11

  9. ∆L 12

  10. a b Collapse of Layers to Higher Multilayers • Collapse of an 8CB monolayer • to trilayer. b. Collapse of a trilayer to a nine-layered stacked interdigitated bilayer structure. [Ref] M.N.G. de Mul & J. A. Mann Jr. -Langmuir 1994,10 14

  11. Acknowledgement Elizabeth K. Mann Lu Zou Ji Wang V. Beleva A. Bernoff J. A. Mann Jr. Supported by NSF, Grant No. 9984304 15

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