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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.


Change of the hydrodynamic radius (Rh) and of scattering intensity divided by the total polymer concentration (I/c) of GBIC-PAPEO14/P2MVPI43 and GBIC-PAPEO14/P2MVPI228 with temperature, at θ = 90°. Experiments were carried out in 10 mM NaCl, pH 7. The total polymer concentrations were 5.45 and 6.01 g/l for GBIC-PAPEO14/P2MVPI43 and GBIC-PAPEO14/P2MVPI228, respectively. Temperature change of 5 °C was obtained within 5 min. Once the desired temperature was reached it was kept constant for the duration of the LS measurements (ten runs, 60 s each)
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Fig6: Change of the hydrodynamic radius (Rh) and of scattering intensity divided by the total polymer concentration (I/c) of GBIC-PAPEO14/P2MVPI43 and GBIC-PAPEO14/P2MVPI228 with temperature, at θ = 90°. Experiments were carried out in 10 mM NaCl, pH 7. The total polymer concentrations were 5.45 and 6.01 g/l for GBIC-PAPEO14/P2MVPI43 and GBIC-PAPEO14/P2MVPI228, respectively. Temperature change of 5 °C was obtained within 5 min. Once the desired temperature was reached it was kept constant for the duration of the LS measurements (ten runs, 60 s each)

Mentions: The Rh of GBIC-PAPEO14/P2MVPI43 and GBIC-PAPEO14/P2MVPI228 have been determined with DLS titrations, at 90˚ detection angle, at the PMC and as a function of the micellar concentration after an equilibration time of about 12 h. As shown in Fig. 5 (left) the observed radii of GBICs are much larger than values reported for regular C3M systems [3, 22]. At low concentrations (c ~ 0.1 g/l), values of 90–110 nm are obtained as compared with 20–30 for regular C3Ms [3, 22]. Such values are comparable to those reported in a previous paper [9] for concentrations between 0.1 and 0.4 g/l. In the low concentration range, the effect of concentration is relatively weak. However, at concentrations at 5.5 and 6 g/l for GBIC-PAPEO14/P2MVPI43 and GBIC-PAPEO14/P2MVPI228, respectively, we have observed radii of about 400 and 150 nm, respectively (Fig. 6). We anticipate that the larger size of the micelles and the size increase at higher concentrations is a consequence of a secondary aggregation mechanism due to the hydrophobic sticker. However, the stopping mechanism maybe due to hiding of the stickers inside the aggregate upon further growth.Fig. 5


Formation and structure of ionomer complexes from grafted polyelectrolytes.

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

Change of the hydrodynamic radius (Rh) and of scattering intensity divided by the total polymer concentration (I/c) of GBIC-PAPEO14/P2MVPI43 and GBIC-PAPEO14/P2MVPI228 with temperature, at θ = 90°. Experiments were carried out in 10 mM NaCl, pH 7. The total polymer concentrations were 5.45 and 6.01 g/l for GBIC-PAPEO14/P2MVPI43 and GBIC-PAPEO14/P2MVPI228, respectively. Temperature change of 5 °C was obtained within 5 min. Once the desired temperature was reached it was kept constant for the duration of the LS measurements (ten runs, 60 s each)
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Related In: Results  -  Collection

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Fig6: Change of the hydrodynamic radius (Rh) and of scattering intensity divided by the total polymer concentration (I/c) of GBIC-PAPEO14/P2MVPI43 and GBIC-PAPEO14/P2MVPI228 with temperature, at θ = 90°. Experiments were carried out in 10 mM NaCl, pH 7. The total polymer concentrations were 5.45 and 6.01 g/l for GBIC-PAPEO14/P2MVPI43 and GBIC-PAPEO14/P2MVPI228, respectively. Temperature change of 5 °C was obtained within 5 min. Once the desired temperature was reached it was kept constant for the duration of the LS measurements (ten runs, 60 s each)
Mentions: The Rh of GBIC-PAPEO14/P2MVPI43 and GBIC-PAPEO14/P2MVPI228 have been determined with DLS titrations, at 90˚ detection angle, at the PMC and as a function of the micellar concentration after an equilibration time of about 12 h. As shown in Fig. 5 (left) the observed radii of GBICs are much larger than values reported for regular C3M systems [3, 22]. At low concentrations (c ~ 0.1 g/l), values of 90–110 nm are obtained as compared with 20–30 for regular C3Ms [3, 22]. Such values are comparable to those reported in a previous paper [9] for concentrations between 0.1 and 0.4 g/l. In the low concentration range, the effect of concentration is relatively weak. However, at concentrations at 5.5 and 6 g/l for GBIC-PAPEO14/P2MVPI43 and GBIC-PAPEO14/P2MVPI228, respectively, we have observed radii of about 400 and 150 nm, respectively (Fig. 6). We anticipate that the larger size of the micelles and the size increase at higher concentrations is a consequence of a secondary aggregation mechanism due to the hydrophobic sticker. However, the stopping mechanism maybe due to hiding of the stickers inside the aggregate upon further growth.Fig. 5

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.