Urbana–Champaign, Illinois -- Researchers at the University of Illinois have discovered how to reverse the characteristics of polyurea, a discovery they say could transform processes for drug delivery, tissue engineering and packaging.
Jianjun Cheng, an associate professor of materials science and engineering at the university, said: "Polymers with transient stability in aqueous solution, also known as hydrolysable polymers, have been applied in many biomedical applications, such as in the design of drug delivery systems, scaffolds for tissue regeneration, surgical sutures, and transient medical devices and implants.
"The highly inert urea bond makes the inexpensive polymer extremely stable, a property that is suitable for some long-lasting applications."
Cheng and his colleagues developed a class of "hindered urea bond-containing
polymeric materials" or "poly(hindered urea)s" (PHUs). According to the university's College of Engineering team, these are "cheap polymers that can be designed to degrade over a specified time period, making them potentially useful in biomedical and agricultural applications."
"While conventional polyurea are very stable against hydrolysis, PHUs can be completely hydrolysed within a few days," said Cheng.
"Since hindrance is the cause of the bond destabilisation, the hydrolysis kinetics of PHUs can be easily tuned as needed for a specific application. They can potentially be environmentally-friendly green and sustainable materials as well," Cheng added.
"Polyurea usually contains ester and other hydrolysable bonds, such as anhydride, acetal, ketal, or imine, in their backbone structures," said research group member Hanze Ying.
"In this study, we demonstrated the potential of PHUs for the design of water degradable polymeric materials that can be easily synthesized by mixing multifunctional bulky amines and isocyanates, expanding the family of hydrolysable polymers," added Ying.
"Hydrolysable polymers have also been applied in the design of controlled release systems in agriculture and food industries and used as degradable, environmentally friendly plastics and packaging materials."
Cheng added: "These applications usually require short functioning time, complete degradation and clearance of materials after their use."
According to the researchers, the new PHUs potentially have great advantages over many other hydrolysable polymers.
PHUs can be made with inexpensive chemical precursors in ambient conditions via simple and clean chemistry with no catalyst or by-products, making it possible for end-users to control the copolymer recipe for specific use without the need of complicated synthesis apparatus.