Arene-Based Polymers

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Description Photocatalytic system for wide variety of cycloaddition polymerization reactions that form arene-based polymers. Offers excellent spatial, temporal, and molecular weight control for the synthesis of this broad class of smart materials. ​At a Glance Light-gated, two-catalyst system for producing polymers of conjugated arenes Cycloaddition-based polymerization only active during periods of illumination Affords high degree of spatial, temporal, and molecular weight control Suitable for wide variety of monomers, polymers, and cycloaddition reaction types Resulting arene-polymers have application as electronic/smart materials Detailed Description The high demand for renewable energies and innovative technology has pushed for the development of new smart materials.  Polymers incorporating the conjugated arene substructure are one class of such materials and are widely utilized in many detection and photovoltaic devices. This invention provides high levels of control for synthesizing a large number of different polymers that incorporate this substructure and has a wide variety of possible applications in the fabrication of new smart materials. The key to this innovation is the development of a two-catalyst polymerization system. The first catalyst is a photocatalyst that is only active when irradiated by visible light. The photocatalyst must continually activate a second catalyst, the function of which is to catalyze the cycloaddition reaction that grows the polymer chain. The result is that, in contrast to many photoinitiated polymerizations that continue after cessation of the light irradiation, polymerization in this system can be turned on and off solely by controlling the irradiation. This affords excellent spatial and temporal control over the reaction and the resulting arene-rich product (e.g., molecular weight, degree of polymerization). This innovation is applicable to arene-based polymers synthesized using cycloaddition reactions. This includes the popular [2+2+2] cycloaddition reaction as well as other forms, such as [4+2], [3+2], and [2+2+1]. As such, a wide variety of coupling partners are suitable for this technology, including diynes, alkynes, alkenes, nitriles, isocyanates, isocyanides, aldehydes, ketones, imines, ketimines, cyclopropenes, vinyl cyclopropanes, methylene cyclopropanes, among others. As a photochemically gated process for cycloaddition polymerization reactions, this innovation provides unique opportunities for externally regulated catalysis. As a light controlled catalysis (rather than a light initiated reaction), it provides enables quick access to new functional materials. Aside from temporal control of polymer synthesis, light-gated catalysis also affords high levels of spatial control. In addition to traditional arene polymers, this technology may prove useful in the arene functionalization of PDMS (e.g., microfluidic systems), an area that remains largely unexplored and possibly holds the key to new applications of PDMS ​