Concerning the self-association ofN-vinyl pyrrolidone and its effect on the determination of equilibrium constants and the thermodynamics of mixing

Abstract

Hydroxylated (co)polymers form miscible blends with a wide variety of (co)polymers that contain proton acceptor groups, such as esters, ethers, pyridines, etc. The former strongly self-associate through the formation of OH/OH hydrogen bonded interactions, while the latter do not self-associate to any measurable exent. With appropiate self- and interassociation equilibrium constants and anthalpies of hydrogen bond formation, we have been able in the past to successfully predict the phase behavior of such hydrogen bonded polymer blends. At first glance, the vinyul pyrrolidone group appears to be just another proton acceptor and if the appropiate interassociation equilibrium constant value is determined we should be able to predict the phase behavior of hydroxylated (co)polymer blends with (co)polymers containing the vinyl pyrrolidone group. However, it is not that simple. Using infrared spectroscopy we demnstrate in this work that the pyrrlidone group strongly self-associates through transition dipole coupling. Ramifications to the determination of equilibrium constants, the free energy of mixing and the phase behavior of blends involving the vinyl pyrrolidone group are discussed.