Tunable Self-Assembled Elastomers Using Triply Hydrogen-Bonded Arrays

This article describes the synthesis and surpamolecular assembly of polyurethane-based elastomers. Triple hydrogen bonding between novel amidoisocytosine (AIC) and ureidoimidazole (UIM) motifs is used to promote assembly of the material. The material comprises an amorphous phase derived from a telechelic diol and a hard crystalline phase that comprises the supramolecular end groups. The use of a heterocomplementary hydrogen bonding interaction results in two unique features: (1) assembly of the elastomer occurs only in the presence of both components, and (2) different feed ratios used during synthesis allow the materials properties to be tuned as the stoichiometries of the components found in the amorphous and crystalline phases of the material are varied. The approach hence offers supramolecular control over materials properties and results in materials that can be melted and therefore processed at lower temperature compared to standard covalent elastomers.