H n.m.r. study on the sequence length of polysulphide linkages in the copolymer of chloroprene and sulphur

The sulphur rank distribution and the structures of chloroprene units in the chloroprene-sulphur copolymer have been investigated in detail by proton nuclear magnetic resonance spectroscopy (¹H n.m.r.). Two factors, the sulphur rank and the structures of chloroprene units, which complicate the spectrum, were elucidated by modification of the copolymer structure through partial and full reductions of the polysulphide linkages. The populations of the chloroprene units with different structures adjacent to the sulphur units were found to be different from those of the homosequence. It was found that the major sulphur unit in the copolymer is octasulphide, the next disulphide and the least common are the other polysulphides composed of 3–7 sulphur atoms. No evidence of monosulphide was found.