Light-scattering study of the association behavior of styrene-ethylene oxide block copolymers in aqueous solution

Xu, Renliang; Winnik, Mitchell A.; Hallett, F. R.; Riess, Gérard; Croucher, Melvin D.

doi:10.1021/ma00001a014

Cited by 371 publications

(354 citation statements)

References 12 publications

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“…In addition, the apparent diffusion rate (D app ) was found to be identical as the scattering vector (q) changed ( Figure S5), indicating that the micelles are spherical and isotropic because of their undetectable rotational motion [28]. In fact, the regular spherical morphology was also demonstrated by AFM observation for PH-PEG micelles in our previous report [17].…”

Section: Microstructure and Morphology-supporting

confidence: 58%

“…In general, the size of individual core-shell type micelles from an amphiphilic diblock polymer is in the range of several tens of nanometers [23]. However, micelles with a size range of several hundred nanometers are often observed due to intermicellar aggregation in amphiphilic block copolymer systems [28][29][30]. Therefore, we assume that the micelles formed from PH-PEG/PLLA-PEG mixtures would also be secondary aggregates further associated with individual micelles [31].…”

Section: Microstructure and Morphology-mentioning

confidence: 99%

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Physicochemical characteristics of pH-sensitive poly(l-Histidine)-b-poly(ethylene glycol)/poly(l-Lactide)-b-poly(ethylene glycol) mixed micelles

Yin

Lee

Kim

et al. 2008

Journal of Controlled Release

154

109

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A novel pH-sensitive polymeric micellar system composed of poly(L-Histidine)-b-poly(ethylene glycol) and poly(L-Lactide)-b-poly(ethylene glycol) block copolymers was studied by dynamic/static light scattering, spectrofluorimetry and differential scanning calorimetry. The mixed micelles displayed ultra pH sensitivity which could be tuned by varying the mixing ratio of the two polymers. In particular, mixed micelles composed of 25 wt. % poly(L-Lactide)-b-poly(ethylene glycol) exhibited desirable pH dependency which could be used as a drug delivery system that selectively targeted the extracellular pH of acidic solid tumors. Micelles were quite stable from pH 7.4 to 7.0 but underwent a two-stage destabilization as pH decreased further. A significant increase in size and aggregation number was observed when pH dropped to 6.8. Further disruption of the micelle core eventually caused phase separation in the micelle core and dissociation of ionized poly(L-Histidine)-b-poly (ethylene glycol) molecules from the micelles as pH decreased to 6.0. Increased electrostatic repulsions which arise from the progressive protonation of imidazole rings overwhelming the hydrophobic interactions among uncharged neutral blocks is considered to be the mechanism for destabilization of the micelle core.

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Section: Microstructure and Morphology-supporting

confidence: 58%

Section: Microstructure and Morphology-mentioning

confidence: 99%

Physicochemical characteristics of pH-sensitive poly(l-Histidine)-b-poly(ethylene glycol)/poly(l-Lactide)-b-poly(ethylene glycol) mixed micelles

Yin

Lee

Kim

et al. 2008

Journal of Controlled Release

154

109

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“…The nanoparticle size decreased with an increase in the PLA content of the copolymer. 38 These effects can be explained considering two different situations: i) small nanoparticles are initially obtained, which by aggregation can generate agglomerates, 39 as in the case of PEO 5KDa -b-PLA 4.5KDa ; and ii) the PEO chains in aqueous solution can form large thermodynamic reversible complexes, increasing the size. 38 In fact, the nanoparticles obtained from the PEO 5KDa -b-PLA 4.5KDa copolymer (lower PLA content) were significantly larger than those obtained from the PEO 5KDa -b-PLA 10KDa system, suggesting a dependence on the PEO.…”

Section: Preparation Of Nanoparticle Suspensionsmentioning

confidence: 99%

“…Thus, the size distribution obtained by NTA indicates larger sizes compared to the DLS results, due to the contribution of some large particles to the overall dispersion. 39 …”

mentioning

confidence: 99%

Preparation of Polymeric Micelles of Poly(Ethylene Oxide-b-Lactic Acid) and their Encapsulation With Lavender Oil

et al. 2016

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Nanoparticles comprised of the poly(ethylene oxide)-b-poly (lactic acid) diblock copolymer (PEO-b-PLA) with and without the incorporation of lavender oil were prepared by nanoprecipitation. Diblock copolymers based on a fixed PEO block (5 KDa ) and two different PLA segments (4.5 or 10 KDa ) were used. The morphology, encapsulation efficiency, essential oil-polymer interaction and the release kinetics of the active agent in the nanoparticles, were evaluated. The hydrodynamic radius of the nanoparticles determined by light scattering was affected by the size of the poly(lactic acid) (PLA) block. The lavender essential oil encapsulation efficiency (at a concentration of 0.4 μL mL -1 ) determined by UV-VIS spectroscopy was in the range of 70-75%. The in vitro release suggests that the polymeric barrier is able to control the oil release.

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“…Polym solution systems. [12][13][14] However, in these few years, the number of studies on the aqueous system has increased very rapidly.…”

Section: Introductionmentioning

confidence: 99%

Neutron Spin−Echo Study of the Dynamic Behavior of Amphiphilic Diblock Copolymer Micelles in Aqueous Solution

Matsuoka¹,

Yamamoto²,

Nakano³

et al. 2000

Langmuir

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We examined the dynamics of amphiphilic polymer micelles of the diblock copolymer HOVE-NBVE (hydroxyethylvinyl ether as a hydrophilic segment and n-butylvinyl ether as a hydrophobic segment) in aqueous solution using the neutron spin-echo (NSE) technique. The time-correlation function obtained for the polymer micelles was well fitted by double exponential function, and the fast and slow modes could be estimated separately. The slow mode was dominant at smaller scattering angles, and showed an excellent linearity in Γ(decay rate) vs q 2 (scattering vector) plot. The diffusion coefficient evaluated from its slope and the hydrodynamic radius, Rh, by the Einstein-Stoke equation were consistent with the size of the polymer micelle that was estimated by small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and dynamic light scattering (DLS). Hence, this slow mode reflects the translational diffusion of the polymer micelle in aqueous solution. The fast mode, which was 1 order of magnitude faster than the slow mode, was a major factor for larger scattering angle regions in which the SANS curve showed blob scattering. Thus, the fast mode appears to be an internal motion of the polymer micelle, like the breathing mode of the hydrophilic shell (corona) around the polymer micelle.

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Light-scattering study of the association behavior of styrene-ethylene oxide block copolymers in aqueous solution

Cited by 371 publications

References 12 publications

Physicochemical characteristics of pH-sensitive poly(l-Histidine)-b-poly(ethylene glycol)/poly(l-Lactide)-b-poly(ethylene glycol) mixed micelles

Physicochemical characteristics of pH-sensitive poly(l-Histidine)-b-poly(ethylene glycol)/poly(l-Lactide)-b-poly(ethylene glycol) mixed micelles

Preparation of Polymeric Micelles of Poly(Ethylene Oxide-b-Lactic Acid) and their Encapsulation With Lavender Oil

Neutron Spin−Echo Study of the Dynamic Behavior of Amphiphilic Diblock Copolymer Micelles in Aqueous Solution

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