Surfactants and Polymers in Aqueous Solution

Jönsson, Bo

doi:10.1002/0470856424

Cited by 1,406 publications

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“…This is analogous to the situation of surfactant adsorption at solid surfaces: Surfactants that form spherical micelles show a much smaller coverage of the surface than that of rod micelles. (see, for example, ref 30).…”

Section: Resultsmentioning

confidence: 99%

Effect of the Head-Group Geometry of Amino Acid-Based Cationic Surfactants on Interaction with Plasmid DNA

Jadhav¹,

Maiti²,

Dasgupta³

et al. 2008

Biomacromolecules

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The interaction between DNA and different types of amino acid-based cationic surfactants was investigated. Particular attention was directed to determine the extent of influence of surfactant head-group geometry toward tuning the interaction behavior of these surfactants with DNA. An overview is obtained by gel retardation assay, isothermal titration calorimetry, fluorescence spectroscopy, and circular dichroism at different mole ratios of surfactant/DNA; also, cell viability was assessed. The studies show that the surfactants with more complex/ bulkier hydrophobic head group interact more strongly with DNA but exclude ethidium bromide less efficiently; thus, the accessibility of DNA to small molecules is preserved to a certain extent. The presence of more hydrophobic groups surrounding the positive amino charge also gave rise to a significantly lower cytotoxicity. The surfactant self-assembly pattern is quite different without and with DNA, illustrating the roles of electrostatic and steric effects in determining the effective shape of a surfactant molecule.

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Section: Resultsmentioning

confidence: 99%

Effect of the Head-Group Geometry of Amino Acid-Based Cationic Surfactants on Interaction with Plasmid DNA

Jadhav¹,

Maiti²,

Dasgupta³

et al. 2008

Biomacromolecules

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“…In theory, the cloud point is defined as the temperature at which phase separation, in the form of turbidity, occurs for a 1% polymer concentration [21]. However, in practical applications the cloud point can be defined as the intersection of two straight lines drawn through the curves of absorbance at low and high temperatures, respectively [22], or as the temperature corresponding to 50% of the transmittance found for some reference value [11,23] or as the maximum in the first derivative of absorbance in relation to temperature [24].…”

Section: Cloud Point Determination and Polarized Light Thermal Microsmentioning

confidence: 99%

Aggregation and gelation in hydroxypropylmethyl cellulose aqueous solutions

Silva

Pinto

Antunes

et al. 2008

Journal of Colloid and Interface Science

110

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In this work we present an analysis of the thermal behavior of hydroxypropylmethyl cellulose aqueous solutions, from room temperature to higher temperatures, above gelation. We focus on significant aspects, essentially overlooked in previous work, such as the correlation between polymer hydrophobicity and rheological behavior, and the shear effect on thermal gelation. Micropolarity and aggregation of the polymer chains were monitored by both UV/vis and fluorescence spectroscopic techniques, along with polarized light microscopy. Gel formation upon heating was investigated using rheological experiments, with both large strain (rotational) tests at different shear rates and small strain (oscillatory) tests. The present observations allow us to compose a picture of the evolution of the system upon heating: firstly, polymer reptation increases due to thermal motion, which leads to a weaker network. Secondly, above 55 • C, the polymer chains become more hydrophobic and polymer clusters start to form. Finally, the number of physical crosslinks between polymer clusters and the respective lifetimes increase and a three-dimensional network is formed. This network is drastically affected if higher shear rates, at nonNewtonian regimes, are applied to the system.

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“…PBS-PFP is not water soluble. However, when the concentration of PBS-PFP is 8.3 × 10 -6 M and 0-10 mol of C 12 E 5 with respect to the polymer's monomer unit (0-6 × 10 -4 M) are added, the constituents form a transparent solution with optical changes at the threshold surfactant concentration of 5 × 10 -5 M. This concentration is close to the critical micelle concentration (CMC) of binary aqueous C 12 E 5 , 5 × 10 -5 M. 22 It has been further demonstrated how this results in consequent fluorescence enhancement. 14 In this paper we present a further investigation of the solubilization of an aqueous PBS-PFP/C 12 E 5 mixture at concentrations much higher than those used in the previous study.…”

Section: Introductionmentioning

confidence: 96%

“…14,15,17 This technique can also be used to induce liquid crystallinity as shown for PPP 18,19 and poly-(p-pyridine). 20 Oxyethylene glycol-monoethers (C i E j ) 21,22 are archetypical surfactants widely used in fundamental phase studies of microemulsions, [23][24][25][26][27] block-co-polymers, 28 and micelles. 29,30 The phase behavior of pentaethylene glycol monododecyl ether (ndodecyl pentaoxyethylene glycol ether) (C 12 E 5 ) 31,32 is particularly well-known: Pure C 12 E 5 forms cylindrical micelles but the oil-swollen C 12 E 5 micelles are wormlike with a rather high flexibility and cannot be described as rigid rods.…”

Section: Introductionmentioning

confidence: 99%

Solubilization of Polyelectrolytic Hairy-Rod Polyfluorene in Aqueous Solutions of Nonionic Surfactant

Knaapila¹,

Garamus²,

Pearson³

et al. 2006

J. Phys. Chem. B

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We report on the solubilization, phase behavior, and self-organized colloidal structure of a ternary waterpolyfluorene-surfactant (amphiphile) system comprised of polyelectrolytic poly{1,4-phenylene[9,9-bis(4-phenoxybutylsulfonate)]fluorene-2,7-diyl} (PBS-PFP) in nonionic pentaethylene glycol monododecyl ether (C 12 E 5 ) at 20°C. We show in particular how a high amount (milligrams per milliliter) of polyfluorene can be solubilized by aqueous C 12 E 5 via aggregate formation. The PBS-PFP and C 12 E 5 concentrations of 0.31 × 10 -4 -5 × 10 -4 M and 2.5 × 10 -4 -75 × 10 -4 M, respectively, were used. Under the studied conditions, the photoluminescence (PL), surface tension, static contact angle, and (π-A) isotherm measurements imply that D 2 O-PBS-PFP(C 12 E 5 ) x realizes three phase regimes with an increasing molar ratio of surfactant over monomer unit (x). First, for x e 0.5, the mixture is cloudy. In this regime polymer is only partially dissolved. Second, for 1 e x e 2, the solution is homogeneous. In this regime polymer is dissolved down to the colloidal level. Small-angle neutron scattering (SANS) patterns indicate rigid elongated (polymer-surfactant) aggregates with a diameter of 30 Å and mean length of ∼900 Å. The ratio between contour length and persistence length is less than 3. Third, for x g 4, the solution is homogeneous and there is cooperative binding between polymer and surfactant. Surface tension, contact angle, and surface pressure remain essentially constant with increasing x. A PL spectrum characteristic of single separated polyfluorene molecules is observed. SANS curves show an interference maximum at q ∼ 0.015 Å -1 , indicating an ordered phase. This ordering is suggested to be due to the electrostatic repulsion between polymer molecules adsorbed on or incorporated into the C 12 E 5 aggregates (micelles). On dilution the distance between micelles increases via 3-dimensional packing. In this regime the polymer is potentially dissolved down to the molecular level. We show further that the aggregates (x ) 2) form a floating layer at the air-water interface and can be transferred onto hydrophilic substrates.

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Surfactants and Polymers in Aqueous Solution

Cited by 1,406 publications

References 0 publications

Effect of the Head-Group Geometry of Amino Acid-Based Cationic Surfactants on Interaction with Plasmid DNA

Effect of the Head-Group Geometry of Amino Acid-Based Cationic Surfactants on Interaction with Plasmid DNA

Aggregation and gelation in hydroxypropylmethyl cellulose aqueous solutions

Solubilization of Polyelectrolytic Hairy-Rod Polyfluorene in Aqueous Solutions of Nonionic Surfactant

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