Controlling Cyclopolymerization using additive & Solvent aging experiment of In-situ Nanoparticlization of conjugated polymer

Abstract

First study is about controlling Cyclopolymerization.(CP) Cyclopolymerization of 1,6-heptadiyne derivatives using the Grubbs catalysts have been known to afford conjugated polyenes in low yields in dichloromethane (DCM), the most common solvent for olefin metathesis polymerization and a good solvent for typical conjugated polymers. Based on our previous work that showed highly efficient CP using the Grubbs catalysts in tetrahydrofuran (THF), we developed a new polymerization system using weakly coordinating additives with the third-generation Grubbs catalyst in DCM. The polymerization efficiency of various monomers and their controls dramatically increased by adding 3,5-dichloropyridine, yielding polymers with narrow polydispersity indices (PDIs) at low temperatures. These new reaction conditions not only expand the monomer scope by resolving the solubility concerns of conjugated polymers but also more effectively reduced the chain transfer. Consequently, fully conjugated diblock copolymer was successfully prepared.

Second study is about Solvent aging experiment of in-situ Nanoparticlization of conjugated polymer. (INCP) There were many efforts to understand and mimic the natural structures using amphiphilic block copolymers. However, there were lots of works to induce self-assembly after synthesizing block copolymers such as annealing, dialysis and so on. In our previous study, we found out in-situ formation of supramolecules when we used Meldrums acid substituted monomer as 2nd block. We thought these self-assemblies were induced because of not only insolubility but also strong π-π interaction of conjugated backbone of second block. Shapes of resulting nanoparticles were changed from single spherical core-shell structures to worm-like and aggregated micelles by adjusting the first and second block ratio. Furthermore, we noticed that these structural changes also occurred by solvent aging process. It was possible because block or gradient copolymer containing Meldrums acid substituted CPs has high stability for solvents and additional chance to isoemrization. So, we studied about the conformational changes of nanoparticles synthesized in-situ manner using atomic force microscopy (AFM), Transmission electron microscopy (TEM), dynamic laser light scattering (DLS), and UV/Vis spectrum and so on.