MQ Silicone Copolymers: Synthesis and Surface Activity

Presenter: 

Daniel Flagg

Authors: 

D. H. Flagg, T. J. McCarthy

Author Affiliation: 

University of Massachusetts Amherst, Department of Polymer Science and Engineering

Abstract: 

Trimethylsiloxysilicate polymers (MQ copolymers) are unique hybrid materials that lie at the intersection of particle and molecule. They can be prepared with inorganic silica compositions >70%, yet they are soluble in organic solvents and silicone oils. The first MQ materials were invented by DOW-Corning and GE in the 1950s, and while the patent literature has flourished there is little open literature regarding their synthesis or properties. This is likely due to the highly variable-dependent and delicate synthesis that requires precise engineering controls and equipment for industrial preparation. In addition to the synthetic challenges, MQ copolymers are often referred to with the non-molecular term "resins" and the fact that these are molecules is left unappreciated. In this work, MQ copolymers are reproducibly prepared on the lab scale using a two-step acid-catalyzed sol growth and end-capping reaction. By splitting the growth and end-capping reactions into discrete steps, control of molecular size with relative Mn ~ 2,000 to 15,000 g/mol is achieved. Additionally, functional MQ polymers are synthesized with control of functional density. Further investigations of MQ surface activity were inspired by lab experience and patent claims. The behavior of MQ at interfaces provides additional insight into the chemical and physical structure, as well as the possible applications of these silicone copolymers. MQ copolymers are unique "molecular nanoparticles" that offer unique opportunities. While they are an "old" technology, a fresh new perspective will enable them to function as a platform to address modern challenges in polymer and materials science.