Evaluation of the Physical‐Chemical Properties of Poly(ethylene oxide)‐<i>block</i>‐Poly(propylene oxide) by Different Characterization Techniques

Mansur, Cláudia R. E.; Spinelli, Luciana S.; González, Gaspar; Lucas, Elizabete F.

doi:10.1002/masy.200751202

Cited by 8 publications

(5 citation statements)

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“…The intersection of the extension of these two segments is the average point of the discontinuity and is related to the start of the surfactant's aggregation in solution. The concentration where this point occurs corresponds to the CMC 3–7…”

Section: Introductionmentioning

confidence: 99%

Linear and branched polyoxide‐based copolymers: Methods to determine the CMC

Silva¹,

Mauro²,

Mansur³

2009

J of Applied Polymer Sci

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Evaluation of the physical-chemical properties of aqueous solutions of nonionic surfactants based on polyoxides can be performed by different methods. Depending on the technique used, there can be a significant variation in the critical micelle concentration (CMC) found. This is related to the sensitivity of the technique regarding the unimers and micelles present in the solution as well as the structure of the surfactant evaluated. In this work, the CMC values of aqueous solutions of linear and branched poly(ethylene oxide-polypropylene oxide) (PEO-PPO) block copolymers were determined by tensiometry, fluorescence, and particle size analysis, using copolymers having adjacent structures (that is, hydrophilic and hydrophobic segments located adjacently in the copolymer) and alternating structures. Tensiometry was used to measure the surface tension as a function of the copolymer concentration in aqueous solution. Fluorescence was used to determine the fluorescence intensity of pyrene to plot the graphs of the I 1 /I 3 and I E /I M relations according to the surfactant concentration. Finally, particle size analysis was used to determine the diffusion coefficient of the particles. The results showed that the fluorescence and particle size techniques provide lower (and mutually concordant) CMC values and can be considered more precise because these methods directly analyze the bulk of the solution.

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Section: Introductionmentioning

confidence: 99%

Linear and branched polyoxide‐based copolymers: Methods to determine the CMC

Silva¹,

Mauro²,

Mansur³

2009

J of Applied Polymer Sci

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“…On the other hand, the S units are still in a unhindered environment, i.e., they are completely solvated. [8][9][10][11] Even though A and C signals can be used to follow the kinetic process, both signals present some drawbacks. First, as can be seen in Figure 1, signal A gets wider and overlaps with the DMF d7 solvent signal.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 3 also corroborates that the nanoparticle shell, formed by the S blocks, is in a perfectly solvated liquidstate while the cross-linked 4-VPy blocks are in the central more rigid core, which actually behaves as a solid-like environment. [11] Finally, Figure 4 shows the relative intensity (A/A 0 ) with time obtained from …”

Section: Resultsmentioning

confidence: 99%

Kinetics of Core‐Shell Nanoparticle Formation by Two‐Dimensional Nuclear Magnetic Resonance

Luzuriaga

Pomposo

Grande

et al. 2009

Macromol. Rapid Commun.

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We have studied the kinetics of polymeric nanoparticle formation for poly(styrene-block-4-vinylpyridine) [P(S-b-4-VPy)], chains in a non-selective solvent using 1,4-dibromobutane (DBB) as a cross-linker by means of different nuclear magnetic resonance (NMR) spectroscopy techniques. The kinetic process was followed using (1) H, (13) C, and 2-D Heteronuclear Single Quantum Correlation (HSQC) NMR experiments. The kinetic data obtained from 2-D HSQC and (1) H NMR experiments were in good agreement between them, proving the reliability of the 2-D HSQC NMR technique for the in situ study of the kinetics of core-shell nanoparticle formation. A value of 1.5 × 10(-5) s(-1) was determined for the apparent kinetic constant of the P(S-b-4-VPy)-DBB core-shell nanoparticle formation process.

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“…As mentioned already, the PEO-PPO block copolymers and silicon polyethers grafted with PEO and PPO chains have a peculiar behavior when dissolved in water, because these solutions cloud when submitted to temperature variations, according to their affinities and interactions with the water molecules (Mansur et al, 2007;Silva et al, 2009).…”

Section: Solubility Tests Of the Additivesmentioning

confidence: 97%

“…These surfactants in aqueous solution present phase separation with increasing temperature, due to the rupture of the hydrogen bonds between the ether group of the ethylene oxide and the water molecules. The temperature at which this phenomenon occurs is called the cloud point (CP) (Mansur et al, 1997(Mansur et al, , 2007.…”

Section: Introductionmentioning

confidence: 99%