The Lyotropic Cubic Phase of Model Associative Polymers: Small-Angle X-Ray Scattering (SAXS), Differential Scanning Calorimetry (DSC), and Turbidity Measurements

Abrahmsén-Alami, Susanna; Alami, E.; François, Jeanne

doi:10.1006/jcis.1996.0184

Cited by 48 publications

(52 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The almost linear dependence of the transition concentration on headgroup size is similar to that found for conventional nonionic (polymeric) surfactants (9,10,13,16,17,33). From the literature and our potentiometric experiments it can be derived that electrostatic interactions between polymer backbones are reduced to a large extent at pH 5 due to protonation and counterion binding (34).…”

Section: Steady-state Fluorescence Spectroscopysupporting

confidence: 64%

“…Some studies have been performed on nonionic oligomers with one alkyl chain attached specifically at the end of the oligomer (9)(10)(11)(12), but the largest oligomer contained eight ethylene oxide units. Nonionic polymers of higher molecular weight were also studied, but these all contain two alkyl chains specifically attached at the ends of the polymer chains (13)(14)(15)(16)(17)(18). Therefore these molecules can associate both inter-and intramolecularly.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Aggregation Behavior of Mono-endcapped Hydrophobically Modified Poly(sodium acrylate)s in Aqueous Solution

Klijn

Kevelam

Engberts³

2000

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

Titration microcalorimetry and steady-state fluorescence spectroscopy have been used to study the aggregation of mono-endcapped hydrophobically modified poly(sodium acrylate)s in aqueous solution. Polymers with molecular weights varying between 800 and 31,700 were synthesized by radical polymerization using an initiator and chain transfer agent. The resulting polymers form hydrophobic microdomains in aqueous solutions. The following conditions were applied: no salt and pH 5 and 9, respectively; 1 M sodium citrate and pH 9. At pH 5 the critical aggregation concentration (CAC, the concentration at which microdomains are formed) increases with increasing molecular weight of the polymers. The concentration range for aggregation is about 0.2-2.4 mM. At pH 9 the carboxylic acid groups are deprotonated and electrostatic repulsions are introduced; therefore the concentration for aggregation rises to about 80 mM. Interestingly, in case of polymers having M(n)<1400 the CAC decreases with increasing molecular weight due to a counterion-concentration gradient toward the hydrophobic microdomain. Near the microdomain the counterion binding is increased, reducing the electrostatic repulsions and allowing for lower aggregation concentrations. In the presence of 1 M sodium citrate this anomalous trend is suppressed to a large extent; since the overall counterion binding is increased and the CAC is lower. The concentration for aggregation is then in the same range as at pH 5 in the absence of salt. Copyright 2000 Academic Press.

show abstract

Section: Steady-state Fluorescence Spectroscopysupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Aggregation Behavior of Mono-endcapped Hydrophobically Modified Poly(sodium acrylate)s in Aqueous Solution

Klijn

Kevelam

Engberts³

2000

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

show abstract

“…Additionally, a macroscopic phase separation was visually observed for the samples FP205 at T ≥ 40 °C, but no phase separation was evidenced for the FP204 sample. Such phase separation phenomena are common for hydrocarbon end‐capped telechelic polymers in aqueous solution and imply the formation of a polymer‐poor phase and the segregation of polymer aggregates into a polymer‐reach phase upon heating 32. Therefore, there is an evident relationship between the nonlinearity in the ln k vs. 1/ T relation with increasing temperatures and the occurrence of phase separation.…”

Section: Resultsmentioning

confidence: 99%

“…Fluorinated derivatives present stronger hydrophobic association and a higher viscosifying effect than the corresponding hydrocarbon derivatives 25–30. More recently, PEO derivatives of lower polydispersities than obtained with HEURs have been synthesized by a modification of the hydroxyl groups of PEO with hydrocarbon end caps and replacing the diurethane linker by ether junctions 2,15,31–33. Some attempts leading to perfluoroalkyltelechelic PEOs with linking groups other than diurethane such as ether junctions12,34,35 and ester junctions have been reported 25,36–42.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Hydrolysis of α,ω‐Perfluoroalkyl‐Functionalized Derivatives of Poly(ethylene oxide)

Amado

Kreßler

2005

Macro Chemistry & Physics

View full text Add to dashboard Cite

Summary: Two series of novel α,ω‐perfluoroalkyl terminated esters of poly(ethylene oxide) (PEO) (RF‐PEO) having the general structure CmF2m+1COO(CH2CH2O)nOCCmF2m+1, with m = 1,2,3,4 or 5 have been synthesized. The influences of the PEO molar mass, the length of the perfluoroalkyl group (RF) and temperature on the cleavage of the ester bridge in aqueous solution and the effect of the hydrolysis process on the size of aggregates formed in water were studied. According to 1H and 19F NMR measurements the degree of functionalization obtained (up to 96 mol‐%) increases with the decrease in the length of the RF group. All of the derivatives showed ester cleavage in water in short time scales. The rates of hydrolysis of the ester bridge in aqueous solution were determined from pH‐measurements. It was verified that the rate law for hydrolysis corresponds to a pseudo‐first order type. The hydrolysis kinetic constant k increased with a decrease in the length of the RF group ranging from 0.2 × 10−3 s−1 for the longest RF group (C5F11) up to 1.2 × 10−2 s−1 for the shortest RF group (CF3). The value of k depended almost exclusively on the length of the perfluoroalkyl chain and was independent of the length of the PEO backbone (1 000 or 2 000 g · mol−1), as long as no additional phenomenon such as phase separation was present. It was also found that the change in the value of k with temperature followed a non‐Arrhenius pattern and there was an evident relationship between the non‐linearity in the ln k vs. 1/T relation with increasing temperatures and the occurrence of a macroscopic phase separation of LCST type. Dynamic light scattering measurements showed the coexistence of unimers with associated species with apparent hydrodynamic radii (Rh) of approximately 20–45 nm for all samples in aqueous solutions. These species might correspond to aggregates of a few micelles. For some samples also larger aggregates were found with Rh in the 100–500 nm range, which might be attributed to clusters of micelles. magnified image

show abstract

“…In aqueous solution, hydrophobes tend to aggregate and create a bond between polymer chains by associating interactions. The associating polymers endcapped with hydrophobes form flowerlike micelles beyond a critical micellar concentration [6][7][8]. When the polymer concentration is increased, two flowerlike micelles are connected by bridging.…”

Section: Introductionmentioning

confidence: 99%

Viscosity behavior of silica suspensions flocculated by associating polymers

Kamibayashi

Ogura

Otsubo

2005

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

The Lyotropic Cubic Phase of Model Associative Polymers: Small-Angle X-Ray Scattering (SAXS), Differential Scanning Calorimetry (DSC), and Turbidity Measurements

Cited by 48 publications

References 24 publications

Aggregation Behavior of Mono-endcapped Hydrophobically Modified Poly(sodium acrylate)s in Aqueous Solution

Aggregation Behavior of Mono-endcapped Hydrophobically Modified Poly(sodium acrylate)s in Aqueous Solution

Synthesis and Hydrolysis of α,ω‐Perfluoroalkyl‐Functionalized Derivatives of Poly(ethylene oxide)

Viscosity behavior of silica suspensions flocculated by associating polymers

Contact Info

Product

Resources

About