Dissolution and formation of polyacrylonitrile in low-temperature molten salts

The solubility and the polymerization of polyacrylonitrile in low-temperature molten salts was investigated. It was found, that the polymer dissolves in eutectic mixtures of molten sodium thiocyanate and potassium thiocyanate (NaSCN/KSCN) as well as in the molten hydrate lithium perchlorate (LiClO4*3H2O). The polymer can be regenerated by cooling the melt or diluting with water. The chemical interaction between the molten salt and the polymer was investigated by 13C-NMR spectroscopy. These measurements show that the dissolution of the polymer in molten KSCN/NaSCN is accompanied by the splitting of the the hydrogen bonds. Starting from acrylonitrile, the formation of polyacrylonitrile by a radical polymerization in a molten salt becomes successful. The polymerization of acrylonitrile in an eutectic mixture of KSCN/NaSCN results in the formation of atactic polyacrylonitrile with high molecular weight.