ABSTRACT
The efforts to obtain ladder structures either by a second-stage cyclopolymerization of poly-1,2-butadienes (or poly-3,4-isoprenes), or by a single-stage cyclopolymerization of conjugated dienes have been very closely associated with earlier work on cyclization of natural cis-1,4-polyisoprene and related structures. This chapter discusses the assignment of NMR peaks to cyclic structures in polymers from butadiene and isoprene in an earlier publication. The synthesis of ladder or double-chain polymers by cationic polymerization of conjugated vinylacetylenes in the presence of trichloroacetic acid or boron trifluoride:etherate, followed by heat treatment of the polymers, has been described. A large amount of work in the area of this special type of cyclopolymerization has led to some interesting and unique structures. Thermal stability studies of these unusual structures have been prevalent. Thermal degradation of partial ladderlike polymers of diphenylbutadiene led to a black insoluble residue. The products of the decomposition were identified.
