Synthesis And Properties Of Side-Chain Functional Norbornene Metathesis Polymers

Two types of side-chain functional norbornene-based polymers were prepared via ring-opening metathesis polymerization (ROMP) under Grubbs’third-generation catalyst (Ru-III) which can initiate ROMP effectively due to its versatile and well catalytic activity, good stability and the endurance of functional groups.One is UV-crosslinkable polyimide with carbazole and cinnamate moieties in side chains which could serve as hole-transporting layer in Organic Light-Emitting Diodes (OLED). By introducing carbazole unit into the side chain, the modified polyimide showed excellent optical transparency in the visible region and high thermal stability. By UV-vis spectroscopy and electrochemical test, the bandgap (Eg) and HOMO and LUMO levels of the polymer were calculated as3.76eV,5.80eV and2.04eV, respectively. The suitable lever structure made the polymer has hole-transporting potential. In addition, comparison of the FTIR spectra of the crosslinked scaffold with its pristine sample before crosslinking demonstrates a significant decrease in intensity of the absorption bands of the cyclobutane formation by dimerizing the C=C bonds of the cinnamate groups, the impact of the crosslinking of cinnamate moieties in side chains on the polymeric scaffold solubility could be utilized during the fabrication of the hole-tranporting and light-emitting layer.Another one is a series of donor-acceptor random copolymers with aromatic electron-rich and electron-deficient functional groups along the side chains. The structure and molecular weight of polymers were determined by gel permeation chromatography (GPC) and magnetic resonance spectroscopy (NMR), respectively. The π-π and charge-transfer interactions were investigated by UV-vis absorption spectroscopy (UV-vis) and2D-NMR NOESY. UV-vis absorption spectra showed a new broad absorption band around368nm belonging to π-π and charge-transfer interactions, and the absorbance of the charge-transfer band had a linear relationship with the concentration of copolymer. Thereby the interactions occurred intramolecularly were confirmed.2D-NMR NOESY contour clearly shows a correlation between aromatic protons. This implied the existence of π-π interaction formed by charge transfer between the donor-acceptor side-chains of the copolymers. Summarily, the π-π and charge-transfer interactions were both detected in the donor-acceptor copolymers, and will have its potential applications in many areas, such as molecular recognition, self-assemble, functional materials, and catalysis.