A new class of material—hybrid polymers, which incorporate rigid and soft nano-scale compartments, the latter of which can be removed and regenerated—has been developed by researchers at Northwestern University (Evanston, IL). Capable of contracting and expanding like muscles and rapidly responding to environmental stimuli, the polymers could be used one day to develop implantable materials that function in a life-like way and for use in drug-delivery and energy-source applications.
|Shaped like a ninja star, the hybrid polymer has a hard core with arms
that spiral out; a softer material that can be animated and refreshed
sits between the arms. Image courtesy Mark E. Seniw, Northwestern
"Our discovery could transform the world of polymers and start a third chapter in their history: That of the hybrid polymer," Stupp said. "This would follow the first chapter of broadly useful covalent polymers, then the more recent emerging class of supramolecular polymers."
The covalent rigid skeleton of Stupp's first hybrid polymer has a cross-section shaped like a ninja star, a hard core with arms spiraling out. In between the arms is the softer, so-called life-force material. This is the area that can be animated, refreshed and recharged, features that could be useful in a range of applications.
"Growing the two types of polymers simultaneously generates a structure that is completely different from the two grown alone," Stupp said. "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."
The researchers also discovered that the covalent polymerization that forms the rigid compartment is catalyzed by the supramolecular polymerization, thus yielding much higher molecular weight polymers.
Further research potentially could lead to self-assembling materials with other unique properties, which could have a broad range of applications, according to the scientists.