Monolayers of Symmetric Triblock Copolymers at the Air−Water Interface. 1. Equilibrium Properties

Muñoz, Mercedes G.; Monroy, Francisco; Ortega, Francisco; Rubio, Ramón G.; Langévin, D.

doi:10.1021/la990142a

Cited by 96 publications

(153 citation statements)

References 42 publications

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“…The corresponding surface concentration Γ= 0.4 mg m −2 [11] and surface pressure Π = γ 0 − γ= 10-20 mN m −1 for this transition were also reported [9]. In accordance with published data [4,9,19], we can interpret the changes for PI 88 PEO 334 at around c=1-10 mg L −1 and γ 0 − γ= 10-15 mN m −1 as the tran-sition from a 2D to a 3D structure with PEO chains protruded into the water phase. This scenario is indicated by the abrupt change of the surface scattered intensity and by a smooth change of the ellipsometric parameter J 1 which corresponds to Γ= ca 0.7 mg m −2 (see Fig.…”

Section: Interfacial Regimessupporting

confidence: 90%

“…This is particularly evident for a PEO-PPO-PEO system (Synperionic F68, M w =8350, Fluka, Germany [4]). At this point, two main differences between the behavior of low molecular weight surfactants and high molecular weight amphiphilic polymers should be pointed out.…”

Section: Interfacial Regimesmentioning

confidence: 99%

“…Note that the two blocks of PI 111 PEO 201 have almost identical Flory radii, whereas PEO represents the predominant block in PI 88 PEO 334 . The hydrophobic character of PI 111 PEO 201 and PI 88 PEO 334 can be related to the ratio between the Flory radii r = R F,P I /R F,P EO [4]. As one can read in Tab.…”

Section: Amphiphilic Diblock Copolymersmentioning

confidence: 99%

“…Up to date, macromolecules at the air-water interface were investigated extensively mainly regarding adsorption kinetics and chain conformation transitions [4,5,6]. The kinetics of adsorption from the bulk phase to the interface could be followed, for instance, by tensiometry and ellipsometry [6,7].…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of amphiphilic diblock copolymers at the air–water interface

Stocco

Tauer

Pispas

et al. 2011

Journal of Colloid and Interface Science

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Two polyisoprene-polyethyleneoxide diblock copolymers with different block length ratios adsorbed to the water surface were investigated by multiple angle of incidence ellipsometry, evanescent wave light scattering, and surface tension experiments. In a semidilute interfacial regime, the transition from a two dimensional to a "mushroom" regime, in which polymer chains form loops and tails in the subphase, was discussed. A diffusion mechanism parallel to the interface was probed by evanescent wave dynamic light scattering. At intermediate concentrations, the interfacial diffusion coefficient D scales with the surface concentration Γ, as D ∼ Γ 0.77 in agreement with the scaling observed for polymer solutions in a semidilute regime. At relatively high concentrations a decreasing of D is discussed in terms of increasing friction due to interactions between polyisoprene chains.

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Section: Interfacial Regimessupporting

confidence: 90%

Section: Interfacial Regimesmentioning

confidence: 99%

Section: Amphiphilic Diblock Copolymersmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Dynamics of amphiphilic diblock copolymers at the air–water interface

Stocco

Tauer

Pispas

et al. 2011

Journal of Colloid and Interface Science

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“…30 The refractive index of monolayers was taken as 1.45, as was suggested earlier for similar block copolymers. 31 A possible variation of the composite refractive index because of the presence of the terminal blocks and partial swelling was estimated introducing error within (0.1 nm in most cases thus insignificantly affecting the thickness evaluation. The LB monolayers on the silicon substrates were studied with a Dimension-3000 AFM microscope in the "light" tapping mode in accordance to the usual procedure adapted in our lab.…”

Section: Methodsmentioning

confidence: 99%

Thermoresponsive Reversible Behavior of Multistimuli Pluronic-Based Pentablock Copolymer at the Air−Water Interface

et al. 2006

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Surface behavior of the pH-and thermoresponsive amphiphilic ABCBA pentablock copolymer has been studied with respect to the environmental conditions. We demonstrate that the pentablock copolymer poly((diethylaminoethyl methacrylate)-b-(ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)-b-(diethylaminoethyl methacrylate)) possesses reversible temperature changes at the air-water interface in a narrow pH range of the water subphase. Significant diversity in the surface morphology of pentablock copolymer monolayers at different pH and temperatures observed were related to the corresponding reorganization of central and terminal blocks. Remarkable reversible variations of the surface pressure observed for the Langmuir monolayers at pH 7.4 in the course of heating and cooling between 27 and 50Â°C is associated with conformational transformations of terminal blocks crossing the phase line in the vicinity of the lower critical solution temperature point. The observed thermoresponsive surface behavior can be exploited for modeling of the corresponding behavior of pentablock copolymers adsorbed onto various biointerfaces for intracellular delivery for deeper understanding of stimuli-responsive transformations relevant to controlled drug and biomolecules release and retention. Surface behavior of the pH-and thermoresponsive amphiphilic ABCBA pentablock copolymer has been studied with respect to the environmental conditions. We demonstrate that the pentablock copolymer poly((diethylaminoethyl methacrylate)-b-(ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)-b-(diethylaminoethyl methacrylate)) possesses reversible temperature changes at the air-water interface in a narrow pH range of the water subphase. Significant diversity in the surface morphology of pentablock copolymer monolayers at different pH and temperatures observed were related to the corresponding reorganization of central and terminal blocks. Remarkable reversible variations of the surface pressure observed for the Langmuir monolayers at pH 7.4 in the course of heating and cooling between 27 and 50°C is associated with conformational transformations of terminal blocks crossing the phase line in the vicinity of the lower critical solution temperature point. The observed thermoresponsive surface behavior can be exploited for modeling of the corresponding behavior of pentablock copolymers adsorbed onto various biointerfaces for intracellular delivery for deeper understanding of stimuli-responsive transformations relevant to controlled drug and biomolecules release and retention.

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Self‐Assembly of Single‐Walled Carbon Nanotubes into a Sheet by Drop Drying

2005

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Single-walled carbon nanotubes (SWNTs) are currently the focus of extensive interdisciplinary studies because of their unique physical and chemical properties and potential electronic applications, for example, in making sensors and fieldemission devices.[1] Processing of SWNT-based materials into engineered macroscopic materials is still in its infancy; the most successful methods so far have been based on adapting techniques that had been developed in other areas of material science such as colloids and polymers. Recent successes include preparing fibers and ribbons of SWNTs; [2] films of pure SWNTs, [3,4] polymers doped with SWNTs, [5,6] and growth in situ of SWNT arrays. [7] Evaporation of drops on substrates has been used for patterned deposition of solutes onto non-porous substrates, such as in DNA microarrays, [8] nanolithography, [9] protein crystallization, [10] and stretching DNA for hybridization studies. [11,12] Shimoda et al. [13] prepared continuous selfassembled films of SWNT bundles on glass near a receding contact line by solvent evaporation. The moving contact line of a drying drop could be similarly used to form aligned patterns of SWNTs on substrates for making films or for nanofabrication. Drops of a solution on a substrate follow one of two drying mechanisms: either the drop maintains a constant contact angle by de-pinning the contact line (e.g., water on non-wetting substrates [14] ), or the contact line gets pinned and the drop maintains a fixed contact area (e.g., colloidal dispersions [15] ).Deegan and co-workers [15][16][17] have studied the drying of drops of colloidal dispersions and found that the particles deposit in a ring at the periphery of the drop due to capillary flow in which the pinned contact line causes the solvent to flow towards the edge. Recent investigations have also shown the formation of a skin or crust at the free surface of drops of polymers and colloidal suspensions. [18,19] Pauchard and Allain [19] found that the crust may collapse and evolve into different shapes as the surface area remains constant while the drop volume decreases due to solvent evaporation. "Crusting" on the surface of spin-cast films [20,21] is a well-known phenomenon.De Gennes [22] suggested a transport model for crust formation in spin-cast films. Because the glass-transition or gelation temperature of a pure polymer/colloid is higher than that in solution, [19] at any temperature below the glass transition there is a critical particle concentration at which the system transitions from fluid to glassy or gel-like. Evaporation of solvent from the free surface leads to a local increase in concentration of the polymer/suspension at the free surface, and a very thin glassy or gelled crust is formed at the free surface. Here, we investigated drying of a sessile drop of individually suspended SWNTs in an aqueous solution of F68 Pluronic. We found that, instead of assembling on the substrate, the SWNTs selfassemble into a crust at the free surface. This entangled meshlike crust was characterized b...

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Monolayers of Symmetric Triblock Copolymers at the Air−Water Interface. 1. Equilibrium Properties

Cited by 96 publications

References 42 publications

Dynamics of amphiphilic diblock copolymers at the air–water interface

Dynamics of amphiphilic diblock copolymers at the air–water interface

Thermoresponsive Reversible Behavior of Multistimuli Pluronic-Based Pentablock Copolymer at the Air−Water Interface

Self‐Assembly of Single‐Walled Carbon Nanotubes into a Sheet by Drop Drying

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