Mimicking two approaches used by nature may allow more-precise and better-controlled polymer synthesis, report a team of researchers from the University of Warwick, Coventry, U.K., and the University of New South Wales, Sydney, Australia. "The ability to synthesize polymers with such precision and control will enable us to tailor-make polymers for specific needs, with major applications in materials chemistry, nanotechnology and nanomedicine," says Rachel O'Reilly of the Department of Chemistry at Warwick.
The bio-inspired method relies on a combination of segregation and templating for synthetic radical polymerization. Segregation involves isolating individual components in distinct compartments to control chemical reactions and equilibria; templating provides high accuracy in controlling molecular weight and other properties of polymers.
"One of the long-standing goals in synthetic polymer chemistry is to be able to synthesize polymer of well-defined microstructure. Our approach offers much better control over molecular weight distributions, gives access to higher molecular weights, and offers potential to control tacticity and monomer sequence distribution," she notes.
The team polymerized a nucleobase-containing vinyl monomer in the presence of a complementary low-molecular-weight block copolymer template. The daughter polymers produced boasted high molecular weight and extremely low polydispersity. Control is attained by segregating the propagating radicals in discrete micelle cores (Figure 1). More details appear in a recent article in Nature Chemistry.
"We are looking at what level of molecular weight control we can achieve through tuning the aggregation and assembly size. We are also interested in how selective this chemistry can be to make materials with more-advanced recognition properties," O'Reilly says.
"A key challenge is broadening the scope of the method to allow access to other functional polymers and also [to] ensure the method can be made scalable," she adds.