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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
In general, organo-silicon nomenclature is applied to any structure containing at least one silicon atom. Silanes (R4Si) are silicon-containing compounds with one silicon atom and four directly bonded groups. Silicones, containing alternating silicon and oxygen atoms, are cyclic, linear, branched, caged, or three-dimensional polymers of the monomeric siloxy group. The prefix to these siloxane polymers designates the number of silicon atoms in the polymer—that is, disiloxane has two silicon atoms, while trisiloxane has three silicon atoms, etc. Siloxanes and silanes are named similarly; the root describes whether it is a siloxane (Si-O-Si backbone) or silane (only one Si atom), and the organofunctional portion describes the type and amount of substitution: hexamethyldisiloxane, decamethylpentacyclosiloxane, Tris(trimethylsiloxy)silane, and (poly)dimethylsiloxane.
Oncological Applications of MR Spectroscopy
Published in Martin G. Pomper, Juri G. Gelovani, Benjamin Tsui, Kathleen Gabrielson, Richard Wahl, S. Sam Gambhir, Jeff Bulte, Raymond Gibson, William C. Eckelman, Molecular Imaging in Oncology, 2008
Marie-France Penet, Kristine Glunde, Michael A. Jacobs, Noriko Mori, Dmitri Artemov, Zaver M. Bhujwalla
Tumor hypoxia is known to result in resistance to radiation and chemotherapy (47,48). The ability to noninvasively measure tumor hypoxia would be useful for selecting an appropriate therapy. A recent exciting development is the use of 1H MRS to perform tissue oximetry using hexamethyldisiloxane. This new pO2 probe provides the possibility of detecting in vivo (49).
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
Hexamethyl disiloxane, often referred to in silicone nomenclature as “MM,’ is a clear, colorless, linear volatile dimethylsiloxane fluid characterized by a degree of polymerization equal to zero. This material has a viscosity of 0.65 cst and a heat of vaporization of , only slightly higher than the cyclomethicones. However, owing to its lower boiling point and higher vapor pressure, this fluid will completely evaporate even more quickly than , as can be seen in Figure 3. Hexamethyl disiloxane is characterized by the same solubility properties and may be used in the same applications as cyclomethicones or may be blended with cyclic compounds to alter drying times for specific product require-
Cold plasma assisted deposition of organosilicon coatings on stainless steel for prevention of adhesion of Salmonella enterica serovar Enteritidis
Published in Biofouling, 2021
Mayssane Hage, Simon Khelissa, Marwan Abdallah, Hikmat Akoum, Nour-Eddine Chihib, Charafeddine Jama
The chemical composition of the coated samples was studied using Fourrier transform infrared spectroscopy analyses. The TMDS-N2-4.3 and TMDS-N2-3 coatings showed the same infrared bands. These results imply a similar chemical composition for each of the elaborated coatings. However, the infrared spectra showed some differences in the band absorbance intensity with an increase in oxygen flow rates. Hence, the polymerization of the monomer and the chemical structure of the coating are affected by the amount of O2 added to TMDS during the plasma deposition. The chemical groups related to peaks identified in the spectra, showed that TMDS was fragmented by the CRNP reactive species, forming radicals that polymerized on the SS surface. The structure of the deposited film was a polysiloxane-like structure as shown by Quédé et al. (2004). These results are consistent with those reported for hexamethyldisiloxane plasma deposited films by Agres et al. (1996). They suggest that the variation in O2 flow rates permitted the formation of different functional groups inducing some changes in the polymer structure. Moreover, since all the coatings had a similar chemical structure, the difference in the number of cells attaching to each one was surprising. These results suggest that the chemical structure of the coatings was not the factor affecting bacterial attachment and led to the redirection of the research towards the analysis of surface topography. The coating thickness measurements supported the FTIR analyses since the increase in the oxygen flow rate increased the thickness while the nitrogen flow rate did not affect the thickness.
Biomaterial engineering surface to control polymicrobial dental implant-related infections: focusing on disease modulating factors and coatings development
Published in Expert Review of Medical Devices, 2023
Samuel S. Malheiros, Bruna E. Nagay, Martinna M. Bertolini, Erica D. de Avila, Jamil A. Shibli, João Gabriel S. Souza, Valentim A. R. Barão
Moreover, roughness directly affects other physical and chemical surface properties, such as wettability [39,89]. More specifically, the role of wettability and surface-free energy on biological processes and the impact of roughness in both properties [84] have been discussed. The wettability is measured by the contact angle (CA) of water on a surface and varies from 0° to 180° [90]. CA values less than 90°Characterize a hydrophilic surface and, above that, a hydrophobic one [90], in addition, the wettability is also influenced by surface chemical composition and surface-free energy [90]. Within this subject, host and microbial cell attachment and proliferation can be adjusted by altering the aforementioned properties. Hydrophilic surfaces promote a better interaction with biological fluids, such as serum and plasma, and bacterial cells [88]. In this sense, a hydrophobic surface reduces overall biofilm accumulation and seems to specifically allow the adhesion of a more host-compatible and symbiotic bacterial community profile [29]. In fact, our group has shown that a superhydrophobic coating on a titanium surface developed by the glow discharge plasma technology using Ar, O2, and hexamethyldisiloxane gases led to a reduced polymicrobial adhesion (≈8-fold reduction), and the few bacteria able to adhere to the surface presented a health-related microbiome profile [29]. Interestingly, the superhydrophobic profile was achieved by changing the chemical composition of the titanium surface while still allowing a high roughness profile. These data show the possibility of exploring different chemical and physical properties of existing dental implants to turn them into antifouling surfaces to better withstand the oral cavity’s challenges.