Remote control grubbs catalysts that modulate ring‐opening metathesis polymerizations

Abstract

A broad range of stimuli, including light, heat, mechanical force, or changes in chemical potential, may be used to toggle Ru-based catalysts between multiple distinct states of activity. Catalysts with such features offer a means to temporallyand, in some cases, spatially-control a variety of polymerizations, and thus should facilitate access to synthetic macromolecular materials with tunable structures and properties. Due to the intrinsic versatility and robustness of the Grubbs-type catalyst platforms, numerous remotely controlled ring-opening metathesis polymerizations have been introduced. Herein, selected examples of stimuli-responsive catalysts that have been recently used for such purposes are surveyed and discussed. Perspectives on potential opportunities for development and growth as well as an outlook for the field are also provided.

Metathesis Cascade‐Triggered Depolymerization of Enyne Self‐Immolative Polymers**

“…P3 also exhibited an excellent thermal stability with a decomposition temperature (T d ) of 265 8C determined by thermogravimetric analysis (Figure S17). Furthermore, we reason that the integration of the enyne SIPs with stimuli-responsive metathesis catalysts [21] would expand the utility of this technology in materials science. To this end, we incubated P3 with a temperature-dependent catalytic system consisting of 3 mol % second-generation Grubbs catalyst (G2) and 3 mol % tributyl phosphite inhibitor.…”

Metathesis Cascade-Triggered Depolymerization of Enyne Self-Immolative Polymers

“…After these treatments, P3 also maintained the same reactivity towards depolymerization (Figure S12-S15). Furthermore, we reason that the integration of the enyne SIPs with stimuli-responsive metathesis catalysts [22] would expand the utility of this technology in materials science. To this end, we incubated P3 with a temperature-dependent catalytic system consisting of 3 mol% secondgeneration Grubbs catalyst (G2) and 3 mol% tributyl phosphite inhibitor.…”

Potentiostatically Controlled Olefin Metathesis

“…Significant efforts have been directed toward the integration of responsive units − into contemporary catalysts in order to gain control over the corresponding catalyzed transformations. − The units are typically designed to selectively respond to chemical (e.g., pH), − thermal, − photochemical, − mechanical, − redox, − or electrochemical − stimuli. The latter approaches, which include potentiostatic coulometry or bulk electrolysis (BE), feature a number of distinct advantages, including the ability to (1) finely tune the electric potential applied to the reaction mixture, (2) precisely control the extent of the reduction or oxidation reaction, and (3) modulate the redox chemistry in a temporal fashion .…”