Stimuli-responsive supramolecular polymers in water

In summary, we propose the development of a new class of stimuli-responsive, water soluble supramolecular materials including homopolymers, block copolymers, branched polymers and network structures. These materials architectures will be constructed by bringing together polymer building blocks (polymer chains) with specially designed chemical motifs (guest molecules) attached in specific locations (end-groups) on each chain. A unique barrel-shaped host molecule will then be used to spontaneously join together (self-assemble) the polymer building blocks through host-guest recognition chemistry. As the polymeric building blocks will only be held together through a non-covalent (dynamic) linkage, the material architectures will be reversible and switchable, and we hope to develop ways to control them via external stimuli such as electric field, pH, and/or temperature.Currently, very few examples of synthetic stimuli-sensitive, self-assembling supramolecular polymers exist, and the ability to manipulate such systems in an aqueous environment will represent a significant advance in polymer and materials chemistry. The ability to modulate between linear, branched and network-type structures as a function of an external stimulus would be of great utility in a wide variety of applications requiring dynamic control. For example, as these self-assembled systems should be held together quite strongly in water, the research may provide far-reaching implications towards constructing a variety of new synthetic polymer-bio conjugates with applications in drug delivery and medical diagnostics. Furthermore, the different solution properties arising from the switching between a homo-polymer and a block copolymer in the presence of an oxidant or reductant can be coupled to yield a sensor.The proposed research is relevant to a broad section of the polymer and potentially the pharmaceutical industries as it combines fundamental research of self-assembled systems in an aqueous environment. Opening the field of synthetic supramolecular polymers to water-based systems would represent a paradigm shift in current research efforts. Gaining a better understanding of the basic concepts of self-assembly in water should help to bridge the gap between synthetic polymer chemists and biological researchers, thus providing for more immediate combined efforts in drug delivery, diagnostics and sensing between the two communities.