Polyoxyethylene, DRIS

In the first example, procaine penicillin, an aqueous vehicle containing the soluble components (such as lecithin, sodium citrate, povidone, and polyoxyethylene sorbitan monooleate) is filtered through a 0.22 pm membrane filter, heat sterilized, and transferred into a presterilized mixing-filling tank. The sterile antibiotic powder, which has previously been produced by freeze-drying, sterile crystallization, or spray-drying, is aseptically added to the sterile solution while mixing. After all tests have been completed on the bulk formulation, it is aseptically filled. 

Vink [25] found that Fe+ and Cr ions slightly affected the course of oxidative degradation of (1) hydroxyethylcellulose, (2) methylcellulose (both frequently used as dry press binders), (3) polyoxyethylene, (4) polyvinyl alcohol, and (5) polymethacrylic acid (frequently used as steric stabilizers and binders for aqueous ceramic suspensions). 

Gas chromatography has been used to determine arsine in hydrogen-rich mixtures. The arsine was detected on a column containing dioctyl phthalate on polyoxyethylene-glycol as adsorbent with hydrogen as the carrier gas. The limit of detection as arsenious oxide was 0.001 mg. In addition, determinations of down to 4.2 x 10 gl of arsine in silane on various columns have been developed , using dry nitrogen as carrier gas and a... 

Polyoxyethylene alkyl ethers should be stored in an airtight container, in a cool, dry place. 

Polysorbates are stable to electrolytes and weak acids and bases gradual saponification occurs with strong acids and bases. The oleic acid esters are sensitive to oxidation. Polysorbates are hygroscopic and should be examined for water content prior to use and dried if necessary. Also, in common with other polyoxyethylene surfactants, prolonged storage can lead to the formation of peroxides. 

Nanoparticles of all descriptions can be used not only as suspensions but also as freeze-dried powders for reconstitution, incorporated into liposomes, as aerosols, in gels and microspheres (e.g., gelatin), adsorbed onto microparticles, dispersed in soft-gelatin capsules [e.g., in polyoxyethylene glycols (PEGs)], or as mini-depot tablets. 

Silicones have been claimed to improve combing, enhance feel, reduce flyaway, increase shine, reduce drying time, and lock in color [54-56], The most frequently used silicone is dimethicone, which is a polydimethylsiloxane. Other important silicones are dimethiconol, which is a dimethylsiloxane terminated with hydroxyl groups, amodimethicone, which is an amino-substituted silicone, dimethicone copolyol, which is a dimethylsiloxane containing polyoxyethylene and/or propylene side chains, and cyclomethicone, which refers to a class of cyclic dimethyl polysiloxanes ranging from trimer to hexamer ... 

Small-angle X-ray and neutron-scattering (SANS) studies have been used to obtain detailed information on the stmcture of a variety of micelles. According to these studies, the thickness of the Stem layer is 6-9 A for cationic cetyl trimethy-lammonium bromide (CTAB) micelles and anionic sodium dodecyl sulfate (SDS) micelles. For nonionic micelles, the hydrocarbon core is surrounded by a palisade layer, which consists of the polyoxyethylene groups hydrogen-bonded to water molecules. The palisade layer is about 20 A thick for neutral TritonX-100 (TX-lOO) micelles. The radius of the dry, hydrophobic core of TX-lOO is typically 25-27 A [2]. Thus the overall radius of the TX-100 micelle is about 51 A and that of the SDS micelle is about 30 A. So, these stmctures are much bigger in size than a small molecule. The radius of a water molecule is just about 1.5 A. This is why micelles are called nanoscopic materials. We show the stmcture of micelles in Figure 17.1. 

Cerium (IV) oxide nanoparticles were synthesized by Masui et al [236] by use of a two-microemulsion technique. One of the microemulsions contained polyoxyethylene(lO) octylphenyl ether (OP-10) as the surfactant, n-hexyl alcohol as the co-surfactant, cyclohexane as the continuous phase, and an aqueous solution of cerium nitrate as the droplet phase. The second microemulsion was the same except that the droplet phase was an aqueous ammonia solution. The two were mixed to cause precipitation the particles thus obtained were gathered by centrifugation and washing under sonication with methanol, deionized water and acetone. The final treatment involved freeze-drying and vacuum drying. The mean particle size varied with experimental conditions in the range 2.5-4.0 nm. 

The graft copolymer thus obtained was extracted with cyclohexane three times, each for 24 hours, so as to remove unreacted polystyrene. After vacuum drying, it was extracted three times (each lasting 24 hrs) with 20% aqueous solution of ethyl alcohol, in order to remove polyoxyethylene homopolymer. Phenyl content of the graft copolymer and the extracts were measured by a 730 Ultraviolet Spectrophotometer. IR spectra were obtained by a Perkin-Elmer 580B Spectrophometer. 

Isotropic correlation times and spin lattice relaxation times measured by and H-NMR for polyoxyethylene (POE) solutions in a variety of solvents have been computed using the DRIS formalism for isolated polymer chains [8]. For this purpose, the conformational kinetics of POE has been analyzed and kinetic schemes of rotameric transitions have been estimated for the three distinct types of bond pairs (CO, OC), (OC, CC) and (CC, CO) on the backbone. The effective friction coefficient is deduced from the viscosity of the solvent, irrespective of the size of the kinetic unit, assuming environmental effects and chain connectivity constraints to be of secondary importance compared to torsional energy barriers. The reader is referred to [8] for explicit expressions of... 

Fig. 10. Isotropic correlation times Xcon as a function of reciprocal solvent viscosity for polyoxyethylene in dilute solution. Circles represent expoimental data, the line is n-edicted by the DRIS model...

Polyfunctional aliphatic isocyanate (Sumitomo Bayer Urethan Co., Ltd. Sumidur N NCO, 16.5X) was used as a cross-linker. Phosphate ester comprising mainly phosphorated polyoxyethylenated long-chain alcohols (Toho Chemical Industry Co., Ltd RL-210 mean molecular weight, 63O) was used as a surface active agent. Solutions in toluene of these samples were reverse-roll coated onto the film and dried in an air circulating oven at 90 C for 5 minutes. 

Sonochemical Synthesis of M50 Type Steel Nanopowders. A dispersion of 15g (0.0765 mol) of Fe(CO)5, 0.66g of Cr(EtxC6H6-x)2, 0.75g (0.0015 mol) of CpMo(CO)3 and 1.0 g of polyoxyethylene sorbitan trioleate (surfactant) in dry decalin was sonicated at 50% amplitude for 7h at room temperature in a sonochemical reactor fitted with a condenser and gas inlet and outlet tubes connected to a mercury bubbler. The color of the solution turned dark and then black within a few minutes and this reaction mixture was sonicated until the formation of shiny metallic particles was observed on the walls of the reaction vessel. The sonication was then stopped and the decalin solvent was removed from the reaction flask via vacuum distillation. Fine black powder (Yield 4.448g) remained at the bottom of the reactor, which was then isolated, transferred to a vial and coated with mineral oil before the compaction. 

---