Improved sustainability is associated with elastomers that readily breakdown in the environment at end of life and, as importantly, that can be reprocessed/reused long before end of life arises. We report the preparation of silicone elastomers that possess both thermoplasticityreprocessabilityand antioxidant activity. A combination of ionic and H-bonding links natural phenolic antioxidants, including catechol, pyrogallol, tannic acid, and others, to telechelic aminoalkylsilicones. The mechanical properties of the elastomers, including their processability, are intimately linked to the ratio of [ArOH]/[H2NR] that was found to be optimal when the ratio exceeded 1:1.

The high refractive index aromatic compound, binaphthol (BINOL), is readily incorporated into silicone polymer chains using the Piers–Rubinsztajn (PR) reaction; alternating and random linear copolymers, and elastomers are available. The highest refractive index (RI) materials are BINOL rich. It is not possible to directly make high refractive index linear polymers with very short HSi‐capped, telechelic silicone chains, as they do not react cleanly. However, chain extending short vinyl‐capped BINOL macromers with simple arylsilanes using hydrosilylation leads to polymers with a molar mass of up to 8000 and refractive indices of up to 1.58. Elastomers are prepared using similar processes. The reactions are facile to practice and suggest BINOL can be harnessed in these and other processes to augment RI.

Silicone elastomers must be filled/reinforced with fillers, typically fumed silica, as they are otherwise soft and/or weak and prone to tearing. Fumed silica, produced from waste chlorosilanes by combustion, is...

A series of potentially hypercoordinate tin compounds derived from a substitutionally labile stannane was produced to gain access to a library of stannanes and polystannanes for structure/property investigations. Three model triphenylstannanes, containing either a propyloxybiphenyl (11), propylmethoxy (12) or propylthioester (13) group were synthesized in high yields via substitution reactions of the propyl tosylated stannane 4. Compounds 12 and 13 were converted to the appropriate mono-(14, 15) and dichlorido-(18, 19) stannanes via sequential chlorinations with HCl. Further transformation of 18 or 19 to the dihydridos (22, 23) was carried out with the use of an appropriate reducing agent. Structural characterizations by single crystal X-ray diffraction of 12, 14, 18 and 19 were also undertaken and are discussed. Several DFT methods were compared for accuracy in predicting the hypercoordinate geometries of these compounds. The relative energies of hypercoordinate conformers for the propylmethoxystannanes 12, 14, 18, and 22 were determined and the fractional abundance of each conformer in the gas and solution (CHCl3) phase was estimated. Relativistic DFT calculations of 119 Sn NMR chemical shifts were carried out for a series of non-hypercoordinate reference compounds and the conformers, allowing the estimation of Boltzmann-averaged chemical shifts of the propylmethoxystannanes. A semi-crystalline homopolymer (25) was isolated from the dehydropolymerization of 22 using Wilkinson's catalyst. Conversion of the liable tosylated polystannane (24) to a new partially substituted polystannane (28) via nucleophile displacement reactions was achieved. The structures of model stannanes, chlorinated stannanes, hydrido stannanes and polystannanes were confirmed via NMR ( 1 H, 13 C, 119 Sn) spectroscopy, HRMS, and, in the case of the polymers (25, 28), also by elemental analysis, GPC, DSC and PXRD (25).

In this paper we outline two major findings. The first is that we describe how designer hypercoordinate stannanes can be made from simple substitutions, and by extension, designer tin polymers, at least partially, using these methods. The second is that using advanced DFT methods, 119Sn NMR frequencies have been accurately calculated for select hypercoordinate tin compounds. This accuracy provides a means for further investigation of an important bonding interaction in the solution phase, and is of significant interest to small molecule tin chemists.