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Formation and structure of ionomer complexes from grafted polyelectrolytes.

Brzozowska AM, Keesman KJ, de Keizer A, Leermakers FA - Colloid Polym Sci (2011)

Bottom Line: This effect is stronger for GBICs than for GICs, is reversible for GICs and GBIC-PAPEO(14)/P2MVPI(228), and shows some hysteresis for GBIC-PAPEO(14)/P2MVPI(43).The very large difference between the sizes found experimentally for GBICs and the sizes predicted from SCF calculations supports the view that there is some secondary association mechanism.A possible mechanism is discussed.

View Article: PubMed Central - PubMed

ABSTRACT
We discuss the structure and formation of Ionomer Complexes formed upon mixing a grafted block copolymer (poly(acrylic acid)-b-poly(acrylate methoxy poly(ethylene oxide)), PAA(21)-b-PAPEO(14)) with a linear polyelectrolyte (poly(N-methyl 2-vinyl pyridinium iodide), P2MVPI), called grafted block ionomer complexes (GBICs), and a chemically identical grafted copolymer (poly(acrylic acid)-co-poly(acrylate methoxy poly(ethylene oxide)), PAA(28)-co-PAPEO(22)) with a linear polyelectrolyte, called grafted ionomer complexes (GICs). Light scattering measurements show that GBICs are much bigger (~70-100 nm) and GICs are much smaller or comparable in size (6-22 nm) to regular complex coacervate core micelles (C3Ms). The mechanism of GICs formation is different from the formation of regular C3Ms and GBICs, and their size depends on the length of the homopolyelectrolyte. The sizes of GBICs and GICs slightly decrease with temperature increasing from 20 to 65 °C. This effect is stronger for GBICs than for GICs, is reversible for GICs and GBIC-PAPEO(14)/P2MVPI(228), and shows some hysteresis for GBIC-PAPEO(14)/P2MVPI(43). Self-consistent field (SCF) calculations for assembly of a grafted block copolymer (having clearly separated charged and grafted blocks) with an oppositely charged linear polyelectrolyte of length comparable to the charged copolymer block predict formation of relatively small spherical micelles (~6 nm), with a composition close to complete charge neutralization. The formation of micellar assemblies is suppressed if charged and grafted monomers are evenly distributed along the backbone, i.e., in case of a grafted copolymer. The very large difference between the sizes found experimentally for GBICs and the sizes predicted from SCF calculations supports the view that there is some secondary association mechanism. A possible mechanism is discussed.

No MeSH data available.


Related in: MedlinePlus

The LS results: Guinier plot. Experiment was carried out in 1 mM NaCl, pH 7. The total polymer concentration was 2 g/l. Measurements at lowest angles (θ = 30° and 35°) have been excluded from analysis due to a very high measured values, probably due to the presence of larger aggregates in a solution. Lines represent the linear fits to the experimental data
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Fig15: The LS results: Guinier plot. Experiment was carried out in 1 mM NaCl, pH 7. The total polymer concentration was 2 g/l. Measurements at lowest angles (θ = 30° and 35°) have been excluded from analysis due to a very high measured values, probably due to the presence of larger aggregates in a solution. Lines represent the linear fits to the experimental data

Mentions: The M, Nagg, and micellar hydrodynamic radii extrapolated to zero angle (Rh0) determined with DLS and SLS are summarized in Table 3. In Fig. 15, we plot the Guinier approximation of the measured data. According to Eq. 9, Rg can be determined from the slope of the Guinier plot. However, the change of R(θ,Cparticle) as a function of angle of detection (q) was only minor. For GIC-PAPEO22/PAH160 the slope is approximately zero, and for GIC-PAPEO22/P2MVPI43 it is slightly negative. This kind of behaviour is expected for particle sizes within the Rayleigh limit, i.e., particles much smaller than the wavelength of the incoming beam (Rh0 < λ/20 = 27 nm). In this regime, the particles may be considered as point scatterers and there is practically no information about the particle dimensions. Thus Rg values are not reported.Table 3


Formation and structure of ionomer complexes from grafted polyelectrolytes.

Brzozowska AM, Keesman KJ, de Keizer A, Leermakers FA - Colloid Polym Sci (2011)

The LS results: Guinier plot. Experiment was carried out in 1 mM NaCl, pH 7. The total polymer concentration was 2 g/l. Measurements at lowest angles (θ = 30° and 35°) have been excluded from analysis due to a very high measured values, probably due to the presence of larger aggregates in a solution. Lines represent the linear fits to the experimental data
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3102187&req=5

Fig15: The LS results: Guinier plot. Experiment was carried out in 1 mM NaCl, pH 7. The total polymer concentration was 2 g/l. Measurements at lowest angles (θ = 30° and 35°) have been excluded from analysis due to a very high measured values, probably due to the presence of larger aggregates in a solution. Lines represent the linear fits to the experimental data
Mentions: The M, Nagg, and micellar hydrodynamic radii extrapolated to zero angle (Rh0) determined with DLS and SLS are summarized in Table 3. In Fig. 15, we plot the Guinier approximation of the measured data. According to Eq. 9, Rg can be determined from the slope of the Guinier plot. However, the change of R(θ,Cparticle) as a function of angle of detection (q) was only minor. For GIC-PAPEO22/PAH160 the slope is approximately zero, and for GIC-PAPEO22/P2MVPI43 it is slightly negative. This kind of behaviour is expected for particle sizes within the Rayleigh limit, i.e., particles much smaller than the wavelength of the incoming beam (Rh0 < λ/20 = 27 nm). In this regime, the particles may be considered as point scatterers and there is practically no information about the particle dimensions. Thus Rg values are not reported.Table 3

Bottom Line: This effect is stronger for GBICs than for GICs, is reversible for GICs and GBIC-PAPEO(14)/P2MVPI(228), and shows some hysteresis for GBIC-PAPEO(14)/P2MVPI(43).The very large difference between the sizes found experimentally for GBICs and the sizes predicted from SCF calculations supports the view that there is some secondary association mechanism.A possible mechanism is discussed.

View Article: PubMed Central - PubMed

ABSTRACT
We discuss the structure and formation of Ionomer Complexes formed upon mixing a grafted block copolymer (poly(acrylic acid)-b-poly(acrylate methoxy poly(ethylene oxide)), PAA(21)-b-PAPEO(14)) with a linear polyelectrolyte (poly(N-methyl 2-vinyl pyridinium iodide), P2MVPI), called grafted block ionomer complexes (GBICs), and a chemically identical grafted copolymer (poly(acrylic acid)-co-poly(acrylate methoxy poly(ethylene oxide)), PAA(28)-co-PAPEO(22)) with a linear polyelectrolyte, called grafted ionomer complexes (GICs). Light scattering measurements show that GBICs are much bigger (~70-100 nm) and GICs are much smaller or comparable in size (6-22 nm) to regular complex coacervate core micelles (C3Ms). The mechanism of GICs formation is different from the formation of regular C3Ms and GBICs, and their size depends on the length of the homopolyelectrolyte. The sizes of GBICs and GICs slightly decrease with temperature increasing from 20 to 65 °C. This effect is stronger for GBICs than for GICs, is reversible for GICs and GBIC-PAPEO(14)/P2MVPI(228), and shows some hysteresis for GBIC-PAPEO(14)/P2MVPI(43). Self-consistent field (SCF) calculations for assembly of a grafted block copolymer (having clearly separated charged and grafted blocks) with an oppositely charged linear polyelectrolyte of length comparable to the charged copolymer block predict formation of relatively small spherical micelles (~6 nm), with a composition close to complete charge neutralization. The formation of micellar assemblies is suppressed if charged and grafted monomers are evenly distributed along the backbone, i.e., in case of a grafted copolymer. The very large difference between the sizes found experimentally for GBICs and the sizes predicted from SCF calculations supports the view that there is some secondary association mechanism. A possible mechanism is discussed.

No MeSH data available.


Related in: MedlinePlus