Advances in polycarbodiimide chemistry

Over the last 15 years, large strides have been taken with regards to synthesis, catalysis, structural control, and functional application of polycarbodiimides (polyguanidines); a unique class of helical macromolecules that are derived from the polymerization of carbodiimide monomers using transition metal catalysis. This manuscript will provide a summary of the synthesis and characterization studies in addition to the large variety of properties discovered for these systems and potential applications associated with these properties. In large part, it is the chiral helical backbone coupled with synthetically selective pendant groups which has allowed creation of polycarbodiimides spanning a large range of potential applications. Such applications include cooperative chiral materials, liquid crystalline materials, optical sensors and display materials, tunable polarizers, sites for asymmetric catalysis, and recyclable polymers. Manipulation of the two pendant groups that span away from the amidine backbone repeat unit has allowed solubility of these polymers in solvents ranging from cyclohexane to water, maximizing the potential application of these polymers in various media. (C) 2011 Elsevier Ltd. All rights reserved.