(225i) Photoactive Monomer for Light Mediated Ring Opening Metathesis Polymerization

Photo-responsive polymer coatings promise a wide range of applications in the field of smart surfaces and structures. Conventionally these polymers are made separately and then coated on the substrate with different methods. But these coating methods do not have properties required to commercialize this process to have fault free applications. In past decade a new method of surface initiated polymerization has developed tremendously as it overcomes many limitations of conventional methods for surface coating. Here we seek to combine Ring Opening Metathesis polymerization (ROMP) with photo-responsive molecule to introduce a new class of monomer which is capable of photo controlled ROMP. Ring strain is a prerequisite for the ROMP monomer activity to minimize reversibility of the metathesis reaction. With this in mind, we are developing monomer with characteristic property of optically tunable ring strain due to inclusion of azobenzene in the cyclic alkene. In particular, we fine tune the light-induced change in ring strain through computational molecular design. We are synthesizing this series of Photo Active Rings (PAR) using ring closing metathesis and evaluating the dependence of their ROMP kinetics on irradiation. The resulting polymer structure contains a photo-responsive repeat unit in the polymer backbone and an internal alkene for additional polymer modification. Through this work, we introduce a new class of light-responsive ROMP monomers, and evaluate the critical elements of monomer design.