Macromolecular metamorphosis via stimulus-induced transformations of polymer architecture

Abstract

Macromolecular architecture plays a pivotal role in determining the properties of polymers. When designing polymers for specific applications, it is not only the size of a macromolecule that must be considered, but also its shape. In most cases, the topology of a polymer is a static feature that is inalterable once synthesized. Using reversible-covalent chemistry to prompt the disconnection of chemical bonds and the formation of new linkages in situ, we report polymers that undergo dramatic topological transformations via a process we term macromolecular metamorphosis. Utilizing this technique, a linear amphiphilic block copolymer or hyperbranched polymer undergoes 'metamorphosis' into comb, star and hydrophobic block copolymer architectures. This approach was extended to include a macroscopic gel which transitioned from a densely and covalently crosslinked network to one with larger distances between the covalent crosslinks when heated. These architectural transformations present an entirely new approach to 'smart' materials.

Designing Molecular Building Blocks for Functional Polymersomes

“…A thermodynamically selective cycloaddition between maleimide and anthracene or furan functionalized polymers allowed for metamorphosis of linear amphiphilic block‐copolymers and hyperbranced polymers. This technique was applied to produce macroscopic gels which can transition between different density states based on temperature …”

Self‐Assembled Aptamer‐Grafted Hyperbranched Polymer Nanocarrier for Targeted and Photoresponsive Drug Delivery

“…Among different architectures of polymers, hyperbranched, or dendritic, polymers display unique structural features, such as internal cavities and a large number of functional groups in their periphery. As structure begets properties, [7] the presence of internal cavities enables encapsulation of small-molecule cargos like drugs. In addition, peripheral functional groups can serve as handles for further modifications with therapeutic molecules and/or targeting moieties.…”

Supramolecular Competitive Host–Guest Interaction Induced Reversible Macromolecular Metamorphosis

“…Transformation of shape and structure due to changes in surroundings (stimuli) is considered as fundamental condition of survival for living beings. As molecular architectures control the properties of materials, over the past few decades researchers have developed new materials with different architectures to mimic the nature . In this context, materials ranging from polymers to nanomaterials which can respond and adapt to environmental changes have attracted attention …”

“…In case of polymers, not only the size but also the architecture (shape) plays a pivotal role on the polymer properties like aggregation, flowability, strength, etc . With a change in their molecular architecture, their physical and chemical properties also change . Recently, Sumerlin et al successfully demonstrated “macromolecular metamorphosis” (change in macromolecular architecture) by using different Diels–Alder reactions .…”