Tunable Self-Assembled Elastomers Using Triply Hydrogen-Bonded Arrays

Abstract

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.

Hydrogen-bonded supramolecular polyurethanes

“…Because non‐covalent bonds are reversible, the material properties of supramolecular PUs (SPUs) offer an additional level of control through choice of prepolymer constituents and the nature of non‐covalent forces that are used . Thermal responsiveness is a particularly useful attribute of supramolecular polymers, as it predisposes them to application as thermoplastic elastomers .…”

“…Whilst the exact chemical make‐up of industrially formulated PUs is often a commercial secret, they typically utilize aromatic diisocyanates, principally methylene diphenyl diisocyanate (MDI) 1 , toluene diisocyanate 2 and their aliphatic counterparts isophorone diisocyanate 4 and hydrogenated MDI 3 . Typical polyols used as the soft phase of many PUs include poly(ethylene glycol) (PEG) 5 , poly(ethylene‐ co ‐butylene) 6 , polyisobutylene 7 , polycaprolactone (PCL) 8 and polytetrahydrofuran 9 . 1,4‐Butanediol 10 is commonly used as a low‐molecular‐weight covalent chain extender, which introduces rigidity and high abrasion resistance .…”

Computational study of the thermodynamic stabilities of hydrogen-bonded complexes in solution

“…The H-bonding of 1-2 was used to form tunable self-assembled elastomers [48]. The binding between 1 and 2 was complicated by conformational and tautomeric possibilities of the two monomers 1 and 2.…”

Metallo‐supramolecular Crosslinked Polyurethanes

“…Incorporation of specific hydrogen‐bonding groups into PUs has enabled further tailoring of morphology, improvement in mechanical properties, and enhanced functionality including self‐healing and shape memory. Gooch et al prepared PU segments terminated with ureidoimadazole groups that could be chain extended with heterocomplementary amidoisocytosine . The material properties could be tailored by adjusting the feed ratio of the non‐covalent chain extender.…”