Most silicone polymers are characterized by their lack of specificity. They are typically comprised of complex mixtures of polymer chains with broad polydispersity index, imprecise distributions of functional groups and no control over stereochemistry. This is in part a consequence of the instability of the siloxane bond towards acidic/basic conditions; most synthetic protocols for silicone synthesis involve either acid or base. The few reports available show that much narrower ranges of properties can be obtained from well-defined silicones. The Piers-Rubinsztajn (PR) reaction (R3SiOR' + R"3SiH → R3SiOSiR"3 + R'H), catalyzed by B(C6F5)3, permits the synthesis of precise, branched silicones. It is a particularly advantageous route to monofunctional materials that can be further assembled into more complex structures, including dendrimers. One of the key advantages of the PR reaction is the surprisingly lack of redistribution that accompanies the reaction. Thus, once a structure is formed, it can be easily isolated. The ability of the PR reaction to make well defined silicones will be demonstrated in a variety of ways. Branched silicone head groups dramatically affect both the surface activity and antibacterial activity of silicone polyether surfactants. Highly branched silicones oils, which are difficult to make by traditional routes, exhibit viscosity profiles as a function of molecular weight that are distinct from linear fluids. Finally, the ability to make aryl-rich silicones via either phenolic derivatives or silphenylenes will be examined (Figure). In this case, the role of aryl groups within the core will be compared to simple dimethyl and aryl pendant silicone oils.

Tailored silicone structures lead to tailored silicone properties

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.