End-Grafted Polymers with Surfactants:  A Theoretical Model

Currie, E.P.K.; Gucht, Jasper van der; Borisov, Oleg V.; Stuart, Martien A. Cohen

doi:10.1021/la980168m

Cited by 26 publications

(61 citation statements)

References 41 publications

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“…However, the interaction between densely grafted polymers and surfactants at a concentration above the CAC has not been considered. Recently we presented an analytical mean-field model for brushes immersed in a surfactant solution above the CAC, using the Alexander-de Gennes model as a starting point [28]. Quantities of interest in the model are the coverage of the grafted chains by micelles, the height of the grafted layer and the total amount of surfactant adsorbed per unit area, ⌫.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Stuffed brushes: theory and experiment

Currie¹,

Gucht²,

Borisov³

et al. 1999

Pure and Applied Chemistry

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Abstract:The interaction between polymer brushes and mesoscopic particles is investigated both theoretically and experimentally. We present an analytical mean-field theory for a polymer brush (a layer of long polymer chains end-grafted to a substrate) with varying excluded volume interactions between monomer units. This system mimics the reversible adsorption of mesoscopic particles, such as surfactant micelles or proteins, on the grafted chains. The equilibrium structural properties of the brush (the brush thickness and overall degree of complexation) as well as the number of adsorbed particles per unit area, ⌫, are analysed as functions of the affinity between particle and chain, grafting density and excluded volume interactions. In our model ⌫ is found to have a maximum as a function of . Experimentally the adsorption of BSA on a hydrophobic substrate with grafted PEO chains is measured with reflectometry. In the case of short grafted chains the adsorbed amount of BSA, ⌫, decreases continuously with increasing , which agrees with previous results and model calculations in the literature. In the case of long PEO chains, however, ⌫ is found to have a maximum as a function of . Qualitatively the experimental dependence of ⌫ on is found to agree with the results of our mean-field model. PEO chains show no affinity for BSA in the bulk, whereas in a grafted conformation an effective attraction is found. Some comments are made on the nature of this affinity, which is not yet fully understood.

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Section: Introductionmentioning

confidence: 99%

“…The reader is referred to our other paper for a more extensive treatment of the model [28]. In section 3 the preparation of PEO brushes on PS substrates and the adsorption of BSA, followed with reflectometry, are discussed.…”

Section: Introductionmentioning

confidence: 99%

Stuffed brushes: theory and experiment

Currie¹,

Gucht²,

Borisov³

et al. 1999

Pure and Applied Chemistry

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“…This model is based on renormalization of inter-chain excluded volume interactions due to binding of micellar aggregates to the chains [18]. This model can be also applied to describe the adsorption of small globular proteins or other molecules on grafted polymer chains.…”

Section: Introductionmentioning

confidence: 99%

“…The most spectacular prediction made in [18] concerns the possibility of a non-monotonous dependence of the brush thickness on the grafting density. The origin of this effect is the squeezing of adsorbed micelles out of a densely grafted brush with increasing grafting density (or decreasing adsorption energy).…”

Section: Introductionmentioning

confidence: 99%

Grafted polymers with annealed excluded volume: A model for surfactant association in brushes

Currie

Fleer

Stuart

et al. 2000

The European Physical Journal E - Soft Matter

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We present an analytical self-consistent-field (SCF) theory for a neutral polymer brush (a layer of long polymer chains end-grafted to a surface) with annealed excluded volume interactions between the monomer units. This model mimics the reversible adsorption of solute molecules or aggregates, such as small globular proteins or surfactant micelles, on the grafted chains. The equilibrium structural properties of the brush (the brush thickness, the monomer density profile, the distribution of the end segments of the grafted chains) as well as the overall adsorbed amount and the adsorbate density profile are analyzed as a function of the grafting density, the excluded volume parameters and the chemical potential (the concentration) of the adsorbate in the solution. We demonstrate that, when the grafting density is varied, the overall adsorbed amount always exhibits a maximum, whereas the root-mean-square brush thickness either increases monotonically or passes through a (local) minimum. At high grafting densities the chains are loaded by adsorbed aggregates preferentially in the distal region of the brush, whereas in the region proximal to the grafting surface depletion of aggregates occurs and the polymer brush retains an unperturbed structure. Depending on the relative strength of the excluded volume interactions between unloaded and loaded monomers both the degree of loading of the chains and the polymer density profile are either continuous or they exhibit a discontinuity as a function of the distance from the grafting surface. In the latter case intrinsic phase separation occurs in the brush: the dense phase consists of unloaded and weakly extended chains and occupies the region proximal to the surface, whereas a more dilute phase consisting of highly loaded and strongly extended chains forms the periphery of the brush.

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“…Previous theoretical and experimental studies on polymer/nanoparticle hybrids prepared by diffusing nanoparticles inside swollen homopolymer brushes have provided clear evidence that the penetration depth of the particles depends on the interplay between the size of the particle and the grafting density and molecular weight of the brush. [35][36][37][38][39][40][41] Similar effects are expected to control the distribution of the fluorinating moieties in the P͑HEMA-cofHEMA͒ RCP brushes. In order to address the interplay between the size and reactivity of the modifying agent, we employed a variety of commercially available fluorinated compounds.…”

Section: Resultsmentioning

confidence: 84%

Formation of surface-grafted polymeric amphiphilic coatings comprising ethylene glycol and fluorinated groups and their response to protein adsorption

et al. 2009

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Amphiphilic polymer coatings were prepared by first generating surface-anchored polymer layers of poly(2-hydroxyethyl methacrylate) (PHEMA) on top of flat solid substrates followed by postpolymerization reaction on the hydroxyl terminus of HEMA’s pendent group using three classes of fluorinating agents, including organosilanes, acylchlorides, and trifluoroacetic anhydride (TFAA). The distribution of the fluorinated groups inside the polymer brushes was assessed by means of a suite of analytical probes, including contact angle, ellipsometry, infrared spectroscopy, atomic force microscopy, and near-edge x-ray absorption fine structure spectroscopy. While organosilane modifiers were found to reside primarily close to the tip of the brush, acylchlorides penetrated deep inside PHEMA thus forming random copolymers P(HEMA-co-fHEMA). The reaction of TFAA with the PHEMA brush led to the formation of amphiphilic diblocks, PHEMA-b-P(HEMA-co-fHEMA), whose bottom block comprised unmodified PHEMA and the top block was made of P(HEMA-co-fHEMA) rich in the fluorinated segments. This distribution of the fluorinated groups endowed PHEMA-b-P(HEMA-co-fHEMA) with responsive properties; while in hydrophobic environment P(HEMA-co-fHEMA) segregated to the surface, when in contact with a hydrophilic medium, PHEMA partitioned at the brush surface. The surface activity of the amphiphilic coatings was tested by studying the adsorption of fibrinogen (FIB). While some FIB adsorption occurred on most coatings, the ones made by TFAA modification of PHEMA remained relatively free of FIB.

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End-Grafted Polymers with Surfactants: A Theoretical Model

Cited by 26 publications

References 41 publications

Stuffed brushes: theory and experiment

Stuffed brushes: theory and experiment

Grafted polymers with annealed excluded volume: A model for surfactant association in brushes

Formation of surface-grafted polymeric amphiphilic coatings comprising ethylene glycol and fluorinated groups and their response to protein adsorption

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