Open Access Kent State (OAKS)

A class of polymers synthesized at DuPont in the late 1950's, the polyisocyanates, are the simplest analogs of the Nylons and have proven valuable as experimental models for theories of wormlike macromolecules. The macromolecular dimensional properties associated with all wormlike polymers arise from a strongly preferred local conformation of the chain and in the polyisocyanates this conformation is helical with an interesting additional property in that the mirror helical senses are of equal probability. Recent experiments have shown that discrimination between the helical senses can be accomplished with surprisingly small chiral influences indicating high cooperativity which arises from a conformational state in which long sections of one helical sense are separated from the other sense by infrequent helical reversals. This can be seen to be analogous to theoretical ideas about one-dimensional paramagnetic materials in which the spin states and the domain boundaries are analogs to the helical sense and the helical reversals in the polyisocyanates. The mathematical formalisms of the one-dimensional magnetic materials precisely describe the chiral properties of the polyisocyanates.