Scientists from Northwestern University have developed a completely new type of hybrid polymer with removable supramolecular compartments, which could lead to new concepts in self-healing materials.
The new polymer can be potentially chemically regenerated, programmed to lift weights, contract and expand just like muscles in a human body. The functions require that the polymers have both rigid and soft nano-sized compartments with various properties organized in specific ways.
The hybrid polymer combines polymers with powerful covalent bonds and other polymers with weak non-covalent bonds, popularly known as ‘supramolecular polymers.’ This integrated polymer comprises of two distinct compartments which can be worked on to provide useful features.
Polymers get their features from their nanoscale structure. The covalent rigid skeleton of the hybrid polymer has a cross-section, shaped like a ninja star with arms spiraling out of a rigid core. The arms comprise of a soft ‘life force’ material, which can be animated, refreshed, recharged with features that could be useful in various applications.
“The fascinating chemistry of the hybrid polymers is that growing the two types of polymers simultaneously generates a structure that is completely different from the two grown alone,” said Samuel. I. Stupp, material scientist at Northwestern and senior author of the study. “I can envision this new material being a super-smart patch for drug delivery, where you load the patch with different medications, and then reload it in the exact same compartments when the medicine is gone.”
Stupp further said that the hybrid polymers consist of a unique chemistry which generates a structure that is completely different from the standalone polymers. The new material can eventually become a super-smart patch for drug delivery which can be loaded with different medications and reloaded once depleted.
The researchers discovered that covalent polymerization that forms the rigid compartment can be catalyzed by supramolecular polymerization, yielding high molecular weight polymers.
The strong covalent compartment provides the skeleton and the weakly bonded supramolecular compartment can be regenerated with small molecules once it is used up. After concurrent polymerization of the bonds, the two compartments bond to one another resulting in a long, perfectly shaped cylindrical filament.
“Our discovery could transform the world of polymers and start a third chapter in their history: that of the hybrid polymer,” said Stupp. “This would follow the first chapter of broadly useful covalent polymers, then the more recent emerging class of supramolecular polymers.”
Image courtesy of Mark E. Seniw/Northwestern University