FIG.7.1 Deposition of multilayers using the Langmuir-Blodgett technique: (a and b) monolayer deposition ; and (c and d) multilayer deposition.

TABLE 7.1 IUPAC and Common Names for aVariety of Normal Saturated and Unsaturated Surface Active Compounds

FIG. 7.2 Schematic illustration of a monolayer and a wilhelmy plate arrangement for surface tension measurement: (a) schematic illustration of a barrier delineating the area of a monolayer; and (b) a wilhelmy plate arrangement for measuring the difference in γ on opposite sides of barrier

FIG. 7.3 Schematic profile of the air-water interface that separates a monolayer from the clean surface

FIG. 7.4 Langmuir film balance: (a) a schematic representation of a Langmuir balance; and (b) a Langmuir trough with a laser optic instrument to measure the orientations of the hydrocarbon tails of the surfactant molecules. The apparatus shown monitors the orientation of the tails through the second harmonic signals generated at various angles of incident light beam. (Redrawn with permission of G. A. Somarjai, Introduction to surface Chemistry and Catalysis, Wiley, New York, 1994.)

FIG.7.5 Photograph of a commercial film balance. The photograph shows a”minitrough” with microscopy setup.

FIG. 7.6 Composite two-dimensional pressure π versus area σ isotherm, which includes a wide assortment of monolayer phenomena. Note that scale of the figure is not uniform so that all features may be included on one set of coordinates. The sketches of the surfactants show the orientations of the molecules in each phase at various stages of compression.

FIG. 7.7 Schematic illustration showing the collapse of the film.

FIG. 7.8 A schematic representation of the temperature-versus-area diagram for a Langmuir layer (a two-dimensional phase diagram). The coexistence regions are exaggerated for clarity. The horizontal lines shown ate the tie lines. The arrow marked “quenching” starts at the LE +G coexistence region and is used in the test to illustrate the morphological changes when a two-phase liquid-expanded/gaslike(LE+G) mixture is quenched. (Redrawn with permission of Knobler 1990b)

FIG. 7.9 Fluorescence microscope pictures of a mpnplayer of pentadeconoic acid (PDA) containing 1% fluorescent probe (4-(hexadecylamino)-7-nitrobenz-2-oxa-1,3-diazole, i.e., NBD-hexadecylamine):(A) 1 molecule per 61Ă2 at 25oC with G (dark) and LE (white) phase;(B) 1 molecule per 50 Ă2 at 25oC with G (dark) and LE (while) phase;(C) 1 molecule per 36 Ă2 at 25oC with a single LE phase;(D) 1 molecule per 27Ă2 at 25oC with LC (dark) and LE (white) phase;(E) 1 molecule per 24Ă2 at 25oC with LC (dark) and LE (white) phase;(F) temperature quench starting at the LE/G coexistence region (overall density = 1 molecule per 51 Ă2 ) . The final point is a three-phase region consisting of LC, LE, and G phases. See the text for details. (Redrawn with permission of Knobler 1990b)

FIG. 10. Plots of πσ/kBT versus π for n-alkyl carboxylic acids: (1) C4,

(2) C5, (3) C6, (4) C8, (5) C10, (6) C12. (Data from N. K. Adam, Chem. Rev.,3,172(1926)).

FIG. 7.11 Schematic representation of a surface viscometer: (a) a monolayer is pushed through a narrow channel; and (b) definition of variables for analysis.

FIG.7.12 Comparison of the water level in two adjacent lakes during the summer, 1957.The ordinate shows the level in the lake with the monolayer; the abscissa is the level in the untreated lake. (Redrawn with permission of LaMer 1962).

FIG. 7.13 Variation of some general property P with perpendicular distance from the surface in the vicinity of an interface between two phase α and β.

FIG. 7.14 Three types of variation of γ with c for aqueous solution: (1) simple organic solutes, (2) simple electrolytes, and (3) amphipathic solutes

FIG. 7.15 Plot of γ versus log10C for the dodecyl ether of hexaeethylene oxide at three temperature: (1) 15oC, (2) 25oC, (3) 35oC. (Redrawn with permission of J. M. Corkill, J. F. Goodman, and R. H. Ottewill, Trans. Faraday Soc.,57,1927(1961) ).

TABLE 7.2 Some Familes of Commercial Surfactants and Specific Examples from Each

FIG. 7.16 Schematic plots of the Langmuir equation showing the significance of the initial slope and the saturation value of the ordinate: (a) the fraction covered versus solute activity; and (b) the number of moles of solute adsorbed per unit weight of adsorbent versus concentration .

FIG. 7.17 Plot of the Langmuir equation in the form given by Equation (75) for data in Example 7.5.

FIG. 7.18 Adsorption on carbon from the ethanol-benzene system. The ordinate equals the total number of moles of solution times the change in solution mole fraction per unit weight of carbon. (Data from F. E. Bartell and C. K. Sloan, J. Am. Chem. Soc.,51,1643(1929)).

FIG. 7.19 Schematic illustration of several configurations of three phase useful in the discussion of detergency and flotation. The shaded region represents the soiled spot in detergency and θ1 is the relevant contact angle; the shaded region is an air bubble in flotation, and θ2 is the appropriate contact angle. The arrows in (b) and (d) indicate flow in the adjacent phase.

FIG. 7.20 An admicelle (a bilayer adsorbed on a solid substrate) as a two-dimensional solvent for a polymerization reaction. (Redrawn with permission of J. Wu, J. H. Harwell, and E. A. O

,Rear, J. Phys. Chem.,91,623(198

7)).

FIG. 7.21 An optical switching device based on Langmuir-Blodgett films. (Redrawn with permission of P. Ball 1994.)

FIG. 7.22 Schematic illustration of an apparatus to measure the electrocapillary effect.

FIG. 7.23 Typical electrocapillary curves: (a) anions ara adsorbed; and (b) cations are adsorbed. (Redrawn with permission of N. K. Adam, The Physics and Chemistry of Surfaces, Dover, New York, 1968. )