Polyelectrolyte Poly(<i>tert</i>-butyl acrylate)-<i>block</i>-poly(2-vinylpyridine) Micelles in Aqueous Media

Procházka, Karel; Martin, Thomas; Munk, Petr; Webber, S. E.

doi:10.1021/ma960630e

Cited by 82 publications

(55 citation statements)

References 41 publications

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“…Pyrene is commonly used as a fluorescence probe to monitor micropolarity 50. Pyrene is a condensed aromatic hydrocarbon that is highly hydrophobic and sensitive to the polarity of the surrounding environment.…”

Section: Resultsmentioning

confidence: 99%

Novel Biomimetic Surfactant: Synthesis and Micellar Characteristics

Chen

et al. 2005

Macromolecular Bioscience

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Novel biomimetic surfactants based on cholesterol as the hydrophobic segment and poly[2-(methacryloyloxy)ethyl phosphorylcholine] (pMPC) as the hydrophilic segment were synthesized in the present study by atom transfer radical polymerization (ATRP) of 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) using a cholesterol-based macroinitiator. The association behavior of cholesterol-block-poly[2-(methacryloyloxy)ethyl phosphorylcholine] (Chol-pMPCs) in aqueous solution was studied by (1)H NMR spectroscopy, fluorescence probe technique, and atomic force microscopy (AFM). The (1)H NMR spectrum of the polymer in CD(3)OD showed both the cholesterol group and the phosphorylcholine group while the cholesterol group did not appeared in the (1)H NMR spectrum of the polymer in D(2)O, which implied the formation of a micelle structure. Fluorescence excitation spectra of a pyrene probe solubilized in the aggregates of Chol-pMPCs suggested the presence of a critical micelle concentration (cmc) in water. The critical micelle concentrations of the polymers CMPC10, CMPC20 and CMPC40 were determined to be 7.27 x 10(-3), 13.47 x 10(-3), and 20.77 x 10(-3) mg . mL(-1), respectively. AFM images of the aggregates on mica suggested that the pMPC block formed the biocompatible micelle coronas and the cholesterol block formed the hydrophobic micelle cores. These new biomimetic diblock copolymers were evaluated as "stealthy" nanocapsules for the delivery of hydrophobic drugs. The anti-cancer drug adriamycin (ADR) was chosen as a hydrophobic drug to be incorporated into the inner core of the micelles and the morphology of the drug-loaded micelles were observed by AFM.

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Section: Resultsmentioning

confidence: 99%

Novel Biomimetic Surfactant: Synthesis and Micellar Characteristics

Chen

et al. 2005

Macromolecular Bioscience

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“…The dissolution difficulties of many block copolymers are closely related to the observation that the exchange of single block copolymer chains between aggregates is sometimes very slow, in the range of h or days, or even beyond any detectability [8][9][10] . This observation is generally explained by the fact that the core forming block (in most of the cases polystyrene 1,[4][5][6][8][9][10][11] , but also PMMA 12,13) , poly(tert-butyl acrylate) 14) or poly(lactic acid) 15,16) ) is in the glassy state at room temperature. This means that there is not necessarily a thermodynamic but first of all a kinetic hindrance for chain exchange between these "glassy" or "frozen" micelles.…”

Section: Introductionmentioning

confidence: 99%

Micelle formation of poly(acrylic acid)-block-poly(methyl methacrylate) block copolymers in mixtures of water with organic solvents

Rager

Meyer

Wegner

1999

Macromol. Chem. Phys.

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SUMMARY: The micelle formation of poly(acrylic acid)-block-poly(methyl methacrylate) (AA-MMA) block copolymers in mixtures of water with organic solvents was investigated by non-radiative energy transfer (NRET). In the case of block copolymers with 70 hydrophobic MMA units, which form strongly aggregated micelles in pure water, the addition of a non-selective organic solvent (methanol or 1,4-dioxane) induces a micelle-unimer transition within a relatively small range of solvent composition without significantly increasing the rate of chain exchange between micelles close to this transition region. The addition of 2 vol.-% dimethyl adipate (a solvent with chemical similarity to the PMMA block and only limited solubility in water) does not speed up the chain exchange in this system either. In contrast, this solvent promotes the aggregation of smaller block copolymers (20 or 40 MMA units) which are mainly present as single chains in pure water. In the case of the block copolymer with 40 MMA units the so formed micelles show a very slow chain exchange extending over many days. These observations prompt us to assume that the rate of the micelle-unimer exchange equilibrium is not kinetically hindered (i. e., determined by the T g of the core material of the micelle) but controlled by a strong thermodynamic preference for the aggregated state.

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“…It has been established that I 3 /I 1 decreases with increasing the micropolarity. [10][11][12] For low C p , I 3 /I 1 for all the polymers are estimated to be 0.57-0.60, similar values as that in water. I 3 /I 1 in the presence of polyNaAMPS is almost constant at 0.57-0.63, independent of C p over the whole range examined.…”

Section: Resultsmentioning

confidence: 53%