UCSB researchers addressed the numerous possibilities of multiblock polymers in their latest publication in Science.

Materials professor Glenn Fredrickson and project scientist Kris Delaney reported on the need of a theoretical framework to guide an otherwise overwhelming flood of options in multiblock polymer research in their paper, Multiblock Polymers: Panacea or Pandora’s Box?

Normal polymers are chains of single monomers chemically bound to other monomers of the same species, whereas multiblock polymers connect dissimilar monomers that form repeating blocks.

“Multiblock polymers are an extension [of regular polymers] in which at least two different, chemically distinct types of monomers are combined together,” Delaney said. “The monomers are not joined in a random sequence, though, but rather form ‘blocks’ of many repeated monomers with fixed composition.”

The large spectrum of multiblock polymers offers a wide range of applications in fields such as electronics and medicine.

According to Delaney, the versatility of these polymers stems from their ability to self-assemble.

“The uses of multiblock polymers are quite varied,” Delaney said. “Perhaps the simplest and most widely used in the industry involve combining different blocks to give unique mechanical properties. But the potential uses are much more varied due to the fact that multiblock polymers tend to self-assemble into rich structures with nanometer-sized domains. Such self-assembly is critical in applications ranging from future thin-film microelectronics devices with smaller features, to drug delivery and low-cost solar photovoltaic cells.”

Although researchers in the field have developed a large number of different types of multiblock polymers, the sheer variety of multiblock polymers can be overwhelming.

“If we attempt to study, for example, a ‘decablock’ polymer with six different species, there are more than 2.5 million unique sequences that can be made,” Delaney said. “That is before we start to consider what properties those polymers will eventually have. How and for what purpose do we decide which ones to investigate?”

The researchers propose that a method needs to be developed to sort through the vast number of polymers and their properties.

“We need a new paradigm for investigation,” Delaney said. “Rather than making materials, measuring their properties and stumbling upon favorable ones by accident or by fortuitous matching with a researcher’s intuition, some kind of inverse design process is desirable. That is, to consider the end property that is desired and to sweep through the potential ingredients in some automated way to find those that fit the desired properties.”