화학공학소재연구정보센터
Polymer Bulletin, Vol.70, No.3, 971-984, 2013
Low band gap Schiff base polymers obtained by complexation with Lewis acids
Two Schiff base polymers were prepared from the respective monomers by condensation method using toluene and N-methyl-2-pyrrolidinone as solvent. They were complexed with Al(III), In(III), and Cu(II) trifluoromethane sulfonates (triflates), and AlCl3 Lewis acids and characterized by FT-IR, UV-Vis spectroscopy, and scanning electron microscopy (SEM). Homogeneous films were prepared by spin coating in the presence and absence of Lewis acids. Polymer-Lewis acid interaction was confirmed by FT-IR, UV-Vis spectroscopy, and SEM. Lewis acid composition in polymers was determined by FT-IR spectroscopy. Absorption spectra of these conjugated Schiff base polymer complexes exhibited smaller optical band gap than pristine polymers. These variations ranged from 2.4 to 1.4 and 3.3 to 2.0 eV. Absorption depends on the Lewis acid in the polymer and band gap on the nature of the metal incorporated in the polymeric backbone. Solubility increased by complexation. The obtained complexes were soluble in trifluoroacetic and formic acids and in m-cresol. Polymer-Lewis acid solutions in m-cresol were stable for 98 h; the others remained stable over several months. The results of this study revealed that optical, solubility, and band-gap properties of conjugated Schiff base polymers can be modified by Lewis acids and these could be studied by optoelectronics.