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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.


Left, radial volume fraction φ(r) profiles for water (thin dotted line), the cationic homopolymer (dashed line), and both blocks of the anionic copolymer (solid lines). Both the core and the corona regions are indicated. Right, the corresponding electrostatic potential profile ψ [V] (left ordinate), and the dimensionless charge distribution q/e (right ordinate)
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Fig16: Left, radial volume fraction φ(r) profiles for water (thin dotted line), the cationic homopolymer (dashed line), and both blocks of the anionic copolymer (solid lines). Both the core and the corona regions are indicated. Right, the corresponding electrostatic potential profile ψ [V] (left ordinate), and the dimensionless charge distribution q/e (right ordinate)

Mentions: Figure 16 shows the radial volume fraction profile for a micelle with grand potential (work of formation) Ω ~ 10 kT. This energy must be balanced back by the translation entropy of the micelle. This implies, in this case, a (dilute) micellar volume fraction of φm ~ 10−5. At this micellar concentration, the most-likely micelle carries seven cationic homopolymers and on average just over 11 anionic copolymers to ensure the charge compensation. The micellar core resulting from the applied parameters is well hydrated. However, the experimental estimates for the water content of C3Ms can be up to several tens of percent [28]. This relatively low water content must be attributed to the relatively large number of hydrophobic C segments in the blocks forming the core. The correlation attraction between positively and negatively charged core blocks is neglected in this Poisson–Boltzmann-like treatment of electrostatics. The radial volume fractions in Fig. 16 show that there is a large overlap between the core and the corona forming segments. This overlap is significantly larger than for classical surfactants. The low interfacial tension between core and solvent is due to the broad interface.Fig. 16


Formation and structure of ionomer complexes from grafted polyelectrolytes.

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

Left, radial volume fraction φ(r) profiles for water (thin dotted line), the cationic homopolymer (dashed line), and both blocks of the anionic copolymer (solid lines). Both the core and the corona regions are indicated. Right, the corresponding electrostatic potential profile ψ [V] (left ordinate), and the dimensionless charge distribution q/e (right ordinate)
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Related In: Results  -  Collection

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

Fig16: Left, radial volume fraction φ(r) profiles for water (thin dotted line), the cationic homopolymer (dashed line), and both blocks of the anionic copolymer (solid lines). Both the core and the corona regions are indicated. Right, the corresponding electrostatic potential profile ψ [V] (left ordinate), and the dimensionless charge distribution q/e (right ordinate)
Mentions: Figure 16 shows the radial volume fraction profile for a micelle with grand potential (work of formation) Ω ~ 10 kT. This energy must be balanced back by the translation entropy of the micelle. This implies, in this case, a (dilute) micellar volume fraction of φm ~ 10−5. At this micellar concentration, the most-likely micelle carries seven cationic homopolymers and on average just over 11 anionic copolymers to ensure the charge compensation. The micellar core resulting from the applied parameters is well hydrated. However, the experimental estimates for the water content of C3Ms can be up to several tens of percent [28]. This relatively low water content must be attributed to the relatively large number of hydrophobic C segments in the blocks forming the core. The correlation attraction between positively and negatively charged core blocks is neglected in this Poisson–Boltzmann-like treatment of electrostatics. The radial volume fractions in Fig. 16 show that there is a large overlap between the core and the corona forming segments. This overlap is significantly larger than for classical surfactants. The low interfacial tension between core and solvent is due to the broad interface.Fig. 16

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.