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Organo-Modified Siloxane Polymers for Conditioning Skin and Hair
Published in Randy Schueller, Perry Romanowski, Conditioning Agents for Hair and Skin, 2020
The silicone family of products is extensive. The silicon atom has the ability to accept many different substituents, and the siloxane backbone can take on different structures, which then create the opportunity to change the physical and, as a result, the performance characteristics of functional silicones from: Volatile → range of viscosity → high-melting-point wax Defoamer → profoamer → emulsifier Fluid → elastomeric → resinous powder.Figure 2 shows a pictorial representation of the silicone family of products— dimethyl, alkyl, aromatic, polyethers, amino, and three-dimensional—that are commercially available and commonly used in the personal care industry.
Silicones in Cosmetics
Published in E. Desmond Goddard, James V. Gruber, Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
E. Desmond Goddard, James V. Gruber
As discussed previously, unmodified polydimethylsiloxanes are hydrophobic. Dimethicone copolyols, however, may be hygroscopic depending on the extent of organic glycol modification. The amount of polyether modification required to confer water solubility is typically 2-4 as a ratio of glycol to dimethylsiloxane monomer units. All of the water-soluble dimethicone copolyols, as is characteristic of other ethoxylated surfactants, display inverse temperature solubility. At low temperatures, the polyether groups are fully hydrated, but as temperature increases, the hydrogen bonds between water and polyether groups are broken, and the material becomes insoluble (128). Increasing either the silicone content in the polymer or the molecular weight of the polypropylene oxide chain in a PO or EO/PO modified dimethicone copolyol will result in lower phase separation temperatures (cloud points). There is no such correlation, however, for the compounds modified with only ethylene oxide groups, which become increasingly soluble as the EO content is raised (49). By judicious choice of polyether type and amount, a silicone glycol copolymer may be tailored such that the phase separation temperature permits the dimethicone copolyol to function as a transient defoamer. This application becomes particularly advantageous for foaming compositions that are packaged hot; the antifoaming action of the copolyol in solutions above the cloud point promotes more uniform fill levels and faster packaging times without deaeration of the system.
Fluorescent melamine-formaldehyde/polyamine coatings for microcapsules enabling their tracking in composites
Published in Journal of Microencapsulation, 2022
Christian Neumann, Sophia Rosencrantz, Andreas Schmohl, Latnikova Alexandra
The diuron-PMMA microcapsules were synthesised through solvent evaporation process. In the aqueous phase, 15 g of gum arabic were dissolved at 60 °C in 300 g of deionised water at 450 rpm. Twelve grams PMMA (low molar mass, 18223-0) and 0.004 g Pluronic P-123 were dissolved in chloroform overnight (organic phase). Four grams of diuron were dispersed in the organic phase with the aid of a rotor-stator high speed homogeniser with S25N-25F dispensing tool at 10 000 rpm for 10 s and the organic phase was carefully added to the aqueous phase. During the mixing of the organic and aqueous phase, a rotor-stator high speed homogeniser with S25N-25F dispensing tool at 9000 rpm ensured immediate emulsification without phase separation or formation of agglomerates. After 4 min, a 2-bar stirrer was then switched on at 450 rpm for 90 min (speed homogeniser switched off). 1-Pentanol was used here as a defoamer. After 90 min, the temperature was increased to 65 °C and the mixture was stirred for further 60 min in order to evaporate all of the chloroform. When the synthesis was completed, 200 ml of deionised water were added to the capsule dispersion. After 15 min, the supernatant was decanted off and the sedimented capsules were washed with 400 ml deionised water in the vacuum filtration (filter 4–7 µm) set up.
Development and characterization of a tissue mimicking psyllium husk gelatin phantom for ultrasound and magnetic resonance imaging
Published in International Journal of Hyperthermia, 2020
Lorne W. Hofstetter, Lewis Fausett, Alexander Mueller, Henrik Odéen, Allison Payne, Douglas A. Christensen, Dennis L. Parker
First, a slurry was made by mixing 33.3 g of 250-bloom ballistic gelatin powder (Vyse Gelatin Co., Schiller Park, IL, USA), 1 g of DOWACIL 75 preservative (Dow, Midland, MI, USA), and a specific amount (see below) of psyllium husk powder (Nutricost, Vineyard, UT, USA) with 67.5 ml of degassed deionized water. The preservative DOWICIL was used to prevent phantom spoiling and enabled evaluation of the phantom properties over a longer time period than would have been possible in a phantom constructed without the DOWICIL preservative. Each phantom contained a different amount of psyllium husk: 0.15, 0.3, 0.6, 0.9, 1.5, 2.1, 3.0, 3.9, and 4.8 g, which corresponds to 0.5, 1, 2, 3, 5, 7, 10, 13, and 16 g/L, respectively, where the g/L represents the grams of psyllium husk relative to the total solvent volume (i.e. 300 ml of water and evaporated milk). The psyllium husk was added to increase US scattering while minimizing any alteration of the magnetic properties of the phantom material. Psyllium husk grain size was controlled using #100 and #60 mesh sieves. Only grains passing through the #60 mesh and unable to pass through the #100 mesh were used, ensuring that the approximate psyllium husk grain size was between 150 and 250 µm. Ten drops (∼0.5 ml) of defoamer solution (Vyse Gelatin Co., Schiller Park, IL, USA) were added to the slurry to reduce the formation of bubbles. In a separate container, 82.5 ml of degassed deionized water was mixed with 150 ml of evaporated milk. The evaporated milk/water mixture was heated to 80 °C and then combined with the gelatin/psyllium slurry. This mixture was stirred until the gelatin was fully dissolved.