Formation of Bilayer Disks and Two-Dimensional Foams on a Collapsing/Expanding Liquid-Crystal Monolayer

Friedenberg, Matthew C.; Fuller, Gerald G.; Frank, Curtis W.; Robertson, Channing R.

doi:10.1021/la00016a045

Cited by 115 publications

(105 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In both directions, the growing phase is more or less circular and exhibits coalescence, while the waning phase forms a foam-like structure that withdraws along the isotherm. Foam-like structures have previously been observed for Langmuir films of other amphiphiles, such as 4′-n-octyl-4-cyanobiphenyl upon expansion [25], stearic acid in the liquid-gas coexistence region [26], and poly(dimethylsiloxane) in the submonolayer regime [27].…”

Section: Brewster Angle Microscopymentioning

confidence: 68%

“…To further examine the phase behavior of these Langmuir films, a polarizing film was placed between the lens and detector to detect the presence and relative direction of molecular tilt [25,28]. Examination of films prepared from the three individual amphiphiles showed no regions of differing brightness within or among the phases, thereby giving no measurable indication of collective molecular tilt.…”

Section: Brewster Angle Microscopymentioning

confidence: 99%

See 1 more Smart Citation

Reversible collapse of the Langmuir films of a series of triphenylsilyl ether-terminated amphiphiles

et al. 2011

View full text Add to dashboard Cite

Section: Brewster Angle Microscopymentioning

confidence: 68%

Section: Brewster Angle Microscopymentioning

confidence: 99%

Reversible collapse of the Langmuir films of a series of triphenylsilyl ether-terminated amphiphiles

et al. 2011

View full text Add to dashboard Cite

“…For the case of progressive nucleation, where I is constant, the integral in the exponential term of eq 8 gives (12) At small times, where higher-order terms can be ignored, n = m + 1 > 1, resulting in accelerating rates of collapse. In contrast, if nucleation is instantaneous, then I = I 0 δ (0), and (13) Equations 12 and 13 show that, as with the transformation of bulk materials, instantaneous and progressive nucleation produce values of n that differ by 1. 6, 8, 29 Equation 13 also shows that for instantaneous nucleation n = m could be less than or equal to 1, and the decrease in area could slow.…”

Section: Rates Of Nucleationmentioning

confidence: 99%

“…[9][10][11][12][13][14][15][16][17][18] Binary mixtures of dipalmitoyl phosphatidylcholine (DPPC) with dihydrocholesterol (dchol) form homogeneous films for which the liquid-crystalline collapse through a locus of constant size is particularly well documented. Microscopic images show that the collapse of 30% dchol/DPPC films initially forms bilayer disks on top of the monolayer.…”

Section: Introductionmentioning

confidence: 99%

Kinetics for the Collapse of Trilayer Liquid-Crystalline Disks from a Monolayer at an Air−Water Interface

2005

View full text Add to dashboard Cite

Unlike surfactants considered in previous studies, when phosphatidylcholine (PC) monolayers collapse at constant surface tension to form a 3D bulk phase, surface area decreases at rates that slow. The different kinetics could result from collapse by a distinct mechanism. Rather than the transfer of molecules all along the interface between the monolayer and bulk phase, PC films can collapse by the folding and subsequent sliding of a bilayer over the monolayer. By this mechanism, molecules can transfer to collapsed trilayers through a locus of constant size. In this article, we use the theory of nucleation and growth to show analytically that during collapse, the area can decrease at rates that decelerate when each individual structure grows through a region of fixed dimensions. We also show that binary films of 30% dihydrocholesterol (dchol) and dipalmitoyl phosphatidylcholine (DPPC), which have previously been shown to form a homogeneous monolayer from which trilayer disks grow through a point, collapse with rates of area decay that slow, in agreement with our analytical expressions.

show abstract

“…6,39 For the liquid-crystalline collapse that apparently occurs for the LE phosphatidylcholines, 33 constituents instead flow to the new phase as an intact lamella through a constrained locus. 29,30,32,33 Substances that collapse by different mechanisms might then become metastable at different surface pressures, some of which might be inaccessible at an air/ water interface.…”

Section: Variation Of Collapse Rates With πmentioning

confidence: 99%

Transformation Diagrams for the Collapse of a Phospholipid Monolayer

2004

View full text Add to dashboard Cite

The kinetics of phase transitions in three-dimensional bulk materials are commonly presented in transformation diagrams. Time-temperature transformation (TTT) and continuous-coolingtransformation (CCT) diagrams plot the time required to transform specific fractions of the material to the new phase by cooling below a transition temperature. Transformation occurs isothermally for the TTT diagrams and during continuous cooling through a range of temperatures for CCT curves. Here we present analogous transformation diagrams for two-dimensional monolayers, which collapse at the equilibrium spreading pressure (π e ) to form a three-dimensional bulk phase. Time-surface pressure-transformation (TπT) diagrams give the time required for specific fractions of the film to collapse when surface pressure is constant, and continuouscompression-transformation diagrams give the same information when surface pressure varies continuously. The diagrams, constructed here from previously reported data for 1-palmitoyl-2-oleoyl phosphatidylcholine, provide insights into the behavior of the films. The TπT diagrams successfully predict the existence and approximate magnitude of a threshold rate for compressing the films to high surface pressures above π e and the approximate shape of isotherms obtained with different rates of interfacial compression. The diagrams also caution that the behavior of mixed monolayers, explained previously in terms of compositional changes, can instead result from collapse that varies with surface pressure. Finally, the similarity between the shapes of the TTT and TπT diagrams, with the time for transformation passing through a minimum and then increasing as the systems deviate further from equilibrium, suggests that analogous mechanisms determine the behavior of both systems.

show abstract

Formation of Bilayer Disks and Two-Dimensional Foams on a Collapsing/Expanding Liquid-Crystal Monolayer

Cited by 115 publications

References 0 publications

Reversible collapse of the Langmuir films of a series of triphenylsilyl ether-terminated amphiphiles

Reversible collapse of the Langmuir films of a series of triphenylsilyl ether-terminated amphiphiles

Kinetics for the Collapse of Trilayer Liquid-Crystalline Disks from a Monolayer at an Air−Water Interface

Transformation Diagrams for the Collapse of a Phospholipid Monolayer

Contact Info

Product

Resources

About