Solubilisation capacity of Brij surfactants.

The aim of this study was to investigate the potential of selected Brij non-ionic surfactants for enhancing the solubility of poorly water-soluble drugs. Griseofulvin was selected as a model drug candidate enabling comparisons to be made with the solubilisation capacities of other poly(ethylene oxide)-based copolymers. UV/Vis and (1)H NMR spectroscopies were used to quantify the enhancement of solubility of griseofulvin in 1 wt% aqueous micellar solutions of Brij 78 (C(18)H(37)E(20)), Brij 98 (C(18)H(35)E(20)) and Brij 700 (C(18)H(37)E(100)) (where E represents the OCH(2)CH(2) unit of the poly(ethylene oxide) chain) at 25, 37 and 40 °C.

Effect of water-soluble polymers, polyethylene glycol and poly(vinylpyrrolidone), on the gelation of aqueous micellar solutions of Pluronic copolymer F127.

The micellization of F127 (E(98)P(67)E(98)) in dilute aqueous solutions of polyethylene glycol (PEG6000 and PEG35000) and poly(vinylpyrrolidone) (PVP K30 and PVP K90) is studied. The average hydrodynamic radius (r(h,app)) obtained from the dynamic light scattering technique increased with increase in PEG concentration but decreased on addition of PVP, results which are consistent with interaction of the micelles with PEG and the formation of micelles clusters, but no such interaction occurs with PVP. Tube inversion was used to determine the onset of gelation.

The effect of water-soluble polymers, PEG and PVP, on the solubilisation of griseofulvin in aqueous micellar solutions of Pluronic F127.

The purpose of this study was to investigate the possibility of enhancing the solubilisation capacity of micellar solutions of Pluronic F127 for the poorly water-soluble drug griseofulvin by co-formulating with a water-soluble polymer. The effect of the addition of the polyethylene glycols PEG6000 and 35000, and the poly(vinylpyrrolidone)s PVP K30 and K90, on the solubilisation capacity of 1wt% solutions of Pluronic F127 was related to the effect of these additives on particle size as determined by dynamic light scattering measurements. The addition of PEG35000 to 1wt% F127 solutions significantly increased the solubility capacity expressed in terms of unit weight of F127; PVP K90 had a smaller effect but no enhancement was noted following the addition of PEG6000 or PVP K30.

Flow-induced polymer degradation during ink-jet printing.

We report for the first time evidence of flow-induced polymer degradation during inkjet printing for both poly(methyl methacrylate) (PMMA) and polystyrene (PS) in good solvent. This has significance for the deposition of functional and biological materials. Polymers having Mw either less than 100 kDa or greater than approximately 1,000 kDa show no evidence of molecular weight degradation.

The effect of n-, s- and t-butanol on the micellization and gelation of Pluronic P123 in aqueous solution.

In dilute aqueous solution unimers of copolymer P123 (E(21)P(67)E(21)) associate to form micelles, and in more concentrated solution micelles pack to form high-modulus gels. We are interested in the use of the system as a templating agent in the synthesis of mesoporous materials, and the possibility of determining gel structure, hence mesoporosity, by use of n-, s- or t-butanol. Dynamic light scattering from clear dilute solutions has been used to confirm micellization, visual observation of mobility (tube inversion) to detect gel formation in concentrated solutions, oscillatory rheometry to confirm gel formation and provide values of elastic moduli over a wide temperature range, and small-angle X-ray scattering to determine gel structure.

Solubilisation of drugs in micellar solutions of diblock copolymers of ethylene oxide and styrene oxide.

The solubilisation of two poorly soluble drugs, furosemide and nabumetone, in micellar solutions of diblock copolymers of ethylene oxide and styrene oxide has been studied at 25 and 37 degrees C and solubilisation capacities compared with published values for griseofulvin and docetaxel. Solubilisation in the micelle core, corrected for the different proportions of poly(styrene oxide) in the copolymers, was similar for all four drugs. The highest solubilisation capacities were found for a copolymer with worm-like micelles.

Micellization and drug solubilization in aqueous solutions of a diblock copolymer of ethylene oxide and phenyl glycidyl ether.

The aim of this study was to define a block copolymer micellar system with a high solubilization capacity for poorly soluble aromatic drugs. Ethylene oxide and phenyl glycidyl ether were sequentially polymerized to form the diblock copolymer G5E67 (G = phenyl glycidyl ether, OCH2CH(CH2OC6H5); E = oxyethylene, OCH2CH2; subscripts denote number-average block lengths in repeat units). The association properties in aqueous solution over the range 20-50 degrees C were investigated by surface tensiometry and light scattering, yielding values of the cmc, hydrodynamic radius, and association number; gel boundaries in concentrated micellar solution were investigated by tube inversion.

Block copolymers of ethylene oxide and phenyl glycidyl ether: micellization, gelation, and drug solubilization.

Three triblock copolymers of ethylene oxide and phenyl glycidyl ether, type E(m)G(n)E(m), where G = OCH2CH(CH2OC6H5) and E = OCH2CH2, were synthesized and characterized by gel-permeation chromatography, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, and NMR spectroscopy. Their association properties in aqueous solution were investigated by surface tensiometry and light scattering, yielding values of the critical micelle concentration (cmc), the hydrodynamic radius, and the association number. Gel boundaries in concentrated micellar solution were investigated by tube inversion, and for one copolymer, the temperature and frequency dependence of the dynamic moduli served to confirm and extend the phase diagram and to highlight gel properties.

Micellization of block copolymer P94 in aqueous solution.

P94 is a triblock copolymer of poly(oxyethylene) and poly(oxypropylene), type EPE. Eluent gel permeation chromatography has been used to demonstrate the formation of large micelles in solutions of the copolymer at temperatures immediately above the critical micelle temperature. Values of the critical micelle temperature (cmt) obtained in this way are in excellent agreement with results from differential scanning calorimetry and surface tensiometry.