Antioxidants are important mediators of radical processes. Nature exploits a variety of antioxidants, including vitamins, to moderate oxidation in living systems. Silicone oils and elastomers, widely used in personal care...

The glycol alkoxysilanes, tetrakis(2‐hydroxyethyl)silane (THEOS), and tris(2‐hydroxyethyl)methyl silane (MeTHEOS) are water soluble derivatives of tetraethoxysilane (TEOS) and methyltriethoxysilane (MeTEOS) and precursors of the system silane–chitosan reviewed in this work. The glycol modified alkoxysilanes are obtained by transesterification reaction of TEOS or MeTEOS with ethylene glycol. The reaction evolution is monitored by 29Si NMR. It is possible to observe the formation of the various species of glycol alkoxysilanes in equilibrium as the reaction proceeds showing that the oligomers formation is favored at longer reaction times with the final product tendency to gel keeping the complete water solubility. The glycol alkoxysilanes are synthesized at moderated reaction conditions, by using the Piers–Rubinsztajn (PR) reaction. Additionally, it is already known that THEOS is compatible with different natural polysaccharides as chitosan and the same behavior has been demonstrated in this work for MeTHEOS. Several reports refer studies regarding the system THEOS–polysaccharides to synthesize hybrid materials. The system THEOS–chitosan is known but the characterization as well as the way silane–chitosan interact has not been studied in detail. In the present report, chemical evidence of the covalent interactions THEOS– and MeTHEOS–chitosan based on NMR studies (13C and 29Si) are presented as intended.

Aminosilicones are widely used in commerce for their own interesting properties and as intermediates to organofunctional silicones. Traditional methods for their preparation involve hydrosilylation of allylamine derivatives or nucleophilic displacement of alkyl halides by amines. The former process is compromised by the need for protecting group chemistry, while the preparation of primary amines in the latter case is frequently complicated by overalkylation. Thiol–ene reactions, including to vinylsilicones, are very clean, byproduct-free click reactions. We report that telechelic or pendent vinylsilicones can be converted to the analogous aminoalkylsilicones by the photoinitiated, radical-mediated thiol–ene addition of the natural product cysteamine, which is “naturally” protected in its ammonium form. The product amino sulfide silicone polymers may optionally contain residual vinyl groups. Expensive transition metal catalysts are not required; indeed, platinum catalysts are inhibited by the sulfur-modified aminosilicone products.

The viability of pathogens at interfaces can be disrupted by the presence of (cationic) charge and chelating groups. We report on the synthesis of silicone dendrimers and linear polymers based on a motif of hexadentate ligands with the ability to capture and deliver metal ions. Mono-, di- or trialkoxysilanes are converted in G1 to analogous vinylsilicones and then, iteratively using the Piers-Rubinsztajn reaction and hydrosilylation, each vinyl group is transformed into a trivinyl cluster at G2. The thiol-ene reaction with cysteamine or 3-mercaptopropionic acid and the trivinyl cluster leads to hexadentate ligands 3 × N–S or 3 × HOOC–S. The compounds were shown to effectively capture a variety of metals ions. Copper ion chelation was pursued in more detail, because of its toxicity. On average, metal ions form chelates with 2.4 of the three ligands in a cluster. Upon chelation, viscous oils are converted to (very) soft elastomers. Most of the ions could be stripped from the elastomers using aqueous EDTA solutions, demonstrating the ability of the silicones to both sequester and deliver ions. However, complete ion removal is not observed; at equilibrium, the silicones remain ionically crosslinked.

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