Facile bisurethane supramolecular polymers containing flexible alicyclic receptor units

Abstract

This paper details the synthesis, characterisation and physical analyses of a series of hydrogen bonded urethane supramolecular polymer systems that are created by a facile one-step synthesis from inexpensive and commercially available starting materials. We report the synthesis and characterisation of a series of low molecular weight bisurethanes (<650 a.m.u.) that exhibit physical properties in the bulk that are characteristic of polyurethane materials possessing far higher molecular weight. The physical characteristics of these low molecular weight bisurethanes were investigated by using temperature-dependent rheological analysis and viscometry and the nature in which these compounds assembled was assessed using IR and NMR spectroscopies. These studies reveal that these simple bisurethanes self-assemble via hydrogen bonding interactions.

Hydrogen-bonded supramolecular polyurethanes

“…A key series of studies, aimed towards understanding systematically the role of hydrogen bonding strength as a means of non‐covalent chain extension, set within the context of materials properties, was performed by Hayes and co‐workers. Building on studies concerning the assembly of bis‐urethanes capped with a variety of simple groups capable of hydrogen bonding interactions, Hayes and co‐workers developed urea‐ and carbamate‐terminated MDI–polyisobutylene macromonomers, which were able to self‐assemble into thermally responsive elastomeric materials (Fig. ) .…”

Self‐Assembly Studies of a Chiral Bisurea‐Based Superhydrogelator

“…Herein, based upon previous studies within our group,6 we report an interesting example of a simple chiral bisurea compound ( 1 ) that is able to form hydrogels at very low concentrations (Scheme ). The urea functionality has been used widely in low‐molecular‐weight organogelators because it provides a convenient 1D directionality and strong intermolecular hydrogen‐bonding interactions 7.…”

Structure and Rheological Behavior of Thermoreversible Supramolecular Polymers with Weak Multiple Hydrogen Bonds

“…These polymers feature many interesting properties of covalent polymers with low‐molecular‐weight, due to the reversibility of the noncovalent interactions 4. Because of their directionality and versatility, hydrogen‐bonding has been used for the formation of polymer‐like materials via a self‐assembly process 5–11. Hydrogen‐bonding can provide sufficiently high bond energy when several hydrogen bonds are assembled together, although a single hydrogen bond is not the strongest noncovalent interaction 1, 12–14.…”