Cationic polymerization of dibenzofulvene leading to a π-stacked polymer. (23rd May 2018)

• Record Type: Journal Article
• Authors: Nageh, Hassan; Wang, Yue; Nakano, Tamaki
• Is Part Of: Polymer. Volume 144(2018)
• Page Start: 51
• Page End: 56
• Publication Date: 2018-05-23
• Subjects: Conformation -- Stereochemistry -- Counter ion -- Hypochromism -- Excimer emission; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2018.04.042
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Cationic polymerization of dibenzofulvene is conducted using BF3 -OEt2, CH3 SO3 H, CF3 CO2 H, and CH3 CO2 H as catalyst or initiator in CH2 Cl2 under various conditions. The cationic polymerization leads to controlled stereochemistry and results in a π-stacked polymer through the polymerization. The polymers synthesized using BF3 -OEt2 and CH3 SO3 H appear to possess different π-stacked structures. The polymer made using CH3 SO3 H has an all-trans main-chain C-C bond conformation while the one prepared using BF3 -OEt2 may at least partially have a trans - gauche main-chain C-C bond conformation. π-Stacked conformations are confirmed on the basis of remarkable anisotropy effects on aromatic signals in 1 H NMR spectra, hypochromic effects in electronic absorbance spectra, and dimer (excimer) emission in fluorescence spectra. π-Stacked conformation is found even for oligomer samples with M n of as low as about 700, indicating that the conformation created by the cationic polymerization is rather stable. Graphical abstract: Image 1 Highlights: First trans -gauche π-stacked conformation of poly(dibenzofulvene). Stable trans-gauche π-stack chains with various DP's. Stereo control in cationic polymerization through counter anion effects.