New Bioinspired Polymers Using Electrostatic Force

University of Massachusetts Amherst chemical engineer Sarah L. Perry, working with a colleague at the University of Illinois, is creating new bioinspired materials using electrostatic charge to direct the self-assembly process of long molecules. The research team, working with a class of polymers called coacervates, found they could be modified by changing the sequence of charges along the polymer chain. Coacervates are commonly used in food products and cosmetics. The findings are published in the journal Nature Communications.

Perry and Charles Sing, professor of chemical and biomolecular engineering at the University of Illinois at Urbana-Champaign, collaborated on the research. They say that long chain molecules called polymers are ubiquitous in biology where the precise sequence of chemical building blocks in the chain, known as monomers, encodes the structure and function of life. Perry and Sing are looking for ways to use this kind of chemical patterning to design new synthetic materials.

Perry says, "The idea is to use patterns of chemistry to help design materials, the same way that nature uses amino acids to create functional proteins. We focus on a class of charged polymer solutions, known as complex coacervates, which in water are known to separate like oil and water into a gel-like substance due to the attraction between opposite charges. We show how polymer sequence can be used to tune this separation process; this opens up new possible ways to design materials, where charge patterns are directly synthesized into a polymer to encode for specific properties."

Sing says that in nature, proteins encode information through a precise sequence of monomers. However, this precision control over sequence is much harder to achieve in synthetic polymers. "Instead, we can control the charge placement along the synthetic polymer chains to drive self-assembly processes," he says.

Perry and Sing say that coacervates are commonly used in cosmetics and food products to encapsulate flavors and additives, and as a way of controlling the 'feel' of the product. The challenge has been if there is a need to change the texture or the thickness, manufacturers had to change the material being used.

In this study, Sing and Perry demonstrate that they can rearrange the structure of the polymer chains by tuning their charge to engineer the desired properties. "This is how biology makes the endless diversity of life with only a small number of molecular building blocks," explains Perry. "We envision bringing this bioinspiration concept full circle by using coacervates in biomedical and environmental applications."

Sing and Perry say they hope to expand the use of this process into nanotechnology.

Source: University of Massachusetts Amherst