Supramolecular Polymers containing Sequence-Specific Hydrogen-Bonded End Units

Supramolecular polymers are large molecules composed of repeating structural units (monomers) connected by noncovalent bonds rather than typical covalent chemical bonds. Conventional polymers have excellent properties as materials, but when they melt they become highly viscous. Applications are limited by the high temperature, energy and pressure typically required to provide a melt of sufficiently low viscosity for processing. Noncovalent bonds, such as hydrogen bonding, make supramolecular polymers thermodynamically less stable, adaptable, and more flexible than covalent polymers. Therefore, supramolecular polymers combine good material properties with low-viscosity melts that are easy to handle. The focus on weaker and reversible noncovalent interactions between molecules give rise to interesting and dynamic properties for supramolecular polymers and open up the prospect of many new commercial applications.

Western has available a supramolecular chemistry based on modification of existing polymers with functional end groups capable of selective reactions with other molecules to form hydrogen bonds. These subunits added to the ends of polymers are helical when bonded together, resulting in links which are reinforced by intertwining structure in addition to hydrogen bonding. The result is a system of oligomers which self-assemble with complementary partners in a similar - but entirely synthetic - manner analogous to formation of the DNA double helix (i.e. sequence-specifically). The strength and reversibility of the bonding between monomers can be precisely tuned by installing an array of end groups in the monomers thus allowing several bonds to form. The resulting molecules have completely and repeatedly reversible melting properties, responses to shear stress or solvent effects which are tuneable to suit particular applications.

• Ease of synthesis
• Readily compatible with existing polymer systems
  
• May be incorporated simply and inexpensively into existing covalent polymer frameworks
  
• Precise viscosity or melt properties for a wide range of polymers
  
• Tuneable response to temperature, solvent and stress effects
• Reversible noncovalent bonding interactions make the materials easily removable
  

• Polymer
• Self-assembly
• Supramolecular chemistry
• Hydrogen bonding
• Materials
• Adhesives
• Inkjet inks