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

5. Surface pressure-area isotherm for 8CB 1 2 3 3 1 2 5 [Ref] [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)

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

7. Relaxation of deformed domain 7

10. 10

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

12. 12 ∆L

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

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