Interaction of Surfactant Lamellar Phase and a Strictly Alternating Comb-Graft Amphiphilic Polymer Based on PEG

Yang, Bing; Lal, Jyotsana; Kohn, Joachim; Huang, John S.; Russel, William B.; Prud'homme, Robert Krafft

doi:10.1021/la0105533

Cited by 17 publications

(31 citation statements)

References 31 publications

(71 reference statements)

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“…Influence of the grafted polymers on the elastic properties has been carefully investigated by some researchers. [25][26][27]30,34,41,42,[46][47][48][49] It is known that grafting polymers enhances the bending modulus and the repulsive interaction between membranes. Castro-Roman et al explained the enhancement of the repulsive Helfrich interaction by renormalizing the thickness of polymer layer into an effective thickness of membranes.…”

Section: Development Of the Oily Streak Networkmentioning

confidence: 99%

Shear-induced onion formation of polymer-grafted lamellar phase

et al. 2012

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We study the shear-induced lamellar/onion transformation of the polymer-grafted lamellar phase composed of nonionic surfactant and amphiphilic triblock copolymers. Increase in the mole fraction of polymer X P and the degrees of polymerization of hydrophilic chain N EO remarkably affects the shearinduced onion phase formation behavior. From the viewpoint of the defect-mediated rheology, the shear modulus G 0 is attributed to the oily streak network density. Linear increase in G 0 with preshear rate prior to the onion formation indicates that the increase in the oily streak network density is essential as a pretransition. The oily streak is composed of the focal conic domains (FCDs), which locally have inhomogeneous layer spacing. The critical shear stress s c is well scaled by the effective increment of the bending modulus theoretically predicted for the polymer-grafted membranes, Dk $ X P N 1.27 EO . Experimental results suggest that the shear-induced onion phase is achieved by reorganizing the layer orientation of FCDs with the negative Gaussian curvature in order to eliminate the inhomogeneous layer spacing.

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Section: Development Of the Oily Streak Networkmentioning

confidence: 99%

Shear-induced onion formation of polymer-grafted lamellar phase

et al. 2012

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“…Storage modulus G′ versus oscillation frequency for the bare membrane system (φ ) 0.2) measured after shearing the system at the corresponding shear rate for 2 h. The shear strain is fixed at 3%, which is located in the linear region. The ratio of the product κB h of the hmPAA3%250kpoC 14doped membrane to that of the hmPAA1.5%250kpoC 14doped membrane systems can be calculated by (η 1.5% /η 3% ) 2 on the basis of the definition of the Caille `constant of η ) q o 2 k B T/8π κB h /d because the first-order Bragg peak position q o and the interlamellar spacing d are independent of hydrophobe substitution levels. On the basis of our previous SANS study, 1,2 κB h of the hmPAA3%-250kpoC 14 -doped membrane system is 1.8 times that of the hmPAA1.5%250kpoC 14 -doped membrane system.…”

Section: Figurementioning

confidence: 99%

Effect of Hydrophobically Modified Polymers on Shear-Induced Multilamellar Vesicles

2005

Self Cite

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The effects of polymer concentration, polymer molecular weight, and hydrophobe substitution level of modified poly(acrylic acid) polymers on the formation, size, and viscoelastic properties of shear-induced multilamellar vesicles (onions) are studied by rheology and light diffraction. The onions are close-packed, space-filling vesicles formed by shearing aqueous lamellar phases of C12E5 surfactant to produce phases with sufficient order and size uniformity (O(1-3 microm)) to diffract light. The addition of hydrophobically modified polymers enhances the rate of formation, uniformity, and stability independent of hydrophobe substitution level. Onion size decreases with increasing shear rate as observed for pure surfactant onion systems, but the shear-rate dependence is changed by the polymer. The onion phase has a plateau modulus that increases with polymer concentration but is independent of hydrophobe substitution level or molecular weight. The model presented by Panizza et al. that relates the plateau modulus of the onion phase to membrane rigidity and the compression modulus is consistent with independent measurements of membrane properties from SANS.

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“…5 Following a concept originally proposed by Whitesides, 6 Prud'homme and co-workers recently demonstrated that multivalent polymers provide a cooperative mechanism for stabilization of liposomes and other colloidal particles. [7][8][9][10][11] It was conjectured that, in comparison to polymers with single binding site per chain, polymers with multiple binding sites (i.e., multivalency) can lead to a stronger overall surface absorption thus a higher level of surface protection even when the binding energy for each site is relatively weak. In other words, long polymers with multiple binding sites are more efficient than short polymers with only a single binding site at the same composition.…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study of Cooperativity in Multivalent Polymers for Colloidal Stabilization

Cao

2005

Langmuir

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Multivalent polymers, i.e., copolymers with multiple binding sites, have been proposed recently for stabilization of fusogentic liposomes and other liposomal colloids useful for drug delivery. The performance of such polymers critically depends on their molecular architecture, in particular the strength and frequency of surface anchoring sites along the backbone of a highly soluble polymer. In this work, we investigate the adsorption and surface forces due to multivalent polymers based on coarse-grained polymer models. We find that for W-type polymers that form dangling tails when all anchoring segments are attached to a surface, increasing the chain length at fixed polymer composition leads to a stronger repulsive barrier in the polymer-mediated surface forces thereby increasing the ability of the polymer to stabilize colloidal particles. This prediction conforms to an earlier experiment indicating that increasing the number of hydrophobic anchors along poly(ethylene glycol) polymers results in the cooperative behavior for both surface adsorption and steric stabilization. For M-type multivalent polymers that have weakly anchoring sites placed at the ends, however, addition of binding sites at fixed polymer composition could lead to negative cooperativity, i.e., the more binding sites, the less the amount of adsorption or the weaker the ability of surface protection. The theory also predicts that polymers with two anchoring sites (e.g., telechelic copolymers) are most efficient for colloidal stabilization.

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Interaction of Surfactant Lamellar Phase and a Strictly Alternating Comb-Graft Amphiphilic Polymer Based on PEG

Cited by 17 publications

References 31 publications

Shear-induced onion formation of polymer-grafted lamellar phase

Shear-induced onion formation of polymer-grafted lamellar phase

Effect of Hydrophobically Modified Polymers on Shear-Induced Multilamellar Vesicles

Theoretical Study of Cooperativity in Multivalent Polymers for Colloidal Stabilization

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