Studying the solvation of Polyacrylonitrile in Dimethyl formamide by UV-Vis spectrometry
Polyacrylonitrile (PAN) is a semicrystalline polymer with high larity and is usually processed from solutions. PAN fibers has a wide application in the textile industry, production of high performance carbon fibers, and extensively used in the composite technology for automotive and aerospace technologies due to its good mechanical and fiber-forming properties. Selected solvents for processing influence both the structure and properties of PAN products. The dissolution of highly polar polymers in highly polar solvents is done by breaking up of polar-polar bonds between polymers, followed by forming new polar-polar bonds between polymer and solvent. The solvation properties of polyacrylonitrile (PAN) in N,N-dimethyl formamide (DMF) were studied by the use of UV-Vis spectrometry. At various PAN concentration two absorption peak is observed at l = 275 nm and l = 312 nm corresponds to p®p electronic transition of PAN nitrile (C≡N) group with polar group of solvent molecule (C=O) and electronic transition of strong dipole-dipole interaction between nitrile groups of PAN molecules respectively. Upon increasing aging time, p®p* transition band is bathochromically shifted with respect to time. This spectral effect is explained by an association of groups and/or by a complex formation between DMF and PAN. The UV spectrum of PAN in DMF solution was interpreted in terms of the variety of possible donor-acceptor complex formations.
Scientific adviser - prof. Vladimir Kozlov