The control of polymer structure at both the molecular and supramolecular level is an important goal for the preparation of new materials with designed properties.  One approach to control polymer structure is to preorganize the monomers in the condensed phase in order to carry out a topochemical polymerization. Topochemical polymerizations are rare, only a few fundamental types are known. One of the best examples is the topochemical polymerization of diacetylenes. If the diacetylenes are properly organized then they can undergo a polymerization process to give single crystals of the corresponding polydiacetylene. Unfortunately there is no general method for achieving this required preorganization.

We have developed a host-guest supramolecular approach that partially solves this problem.  One molecule, the host, determines the supramolecular structure and imposes the necessary topochemical parameters upon a second molecule, the guest monomer. Using this approach we have synthesized some fundamentally new types of polydiacetylenes, the first polytriacetylenes and the first topochemical polymerization of a triene. These single crystal to single crystal polymerizations allow us to carry out the reactions with complete control of stereochemistry and to fully characterize the structures of the crystalline products.
 
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7/11/2002