CHICAGO, Aug. 10 (Xinhua) -- Researchers at the University of Illinois (UI) have found a way to use polymer printing to stretch and flatten twisted molecules so that they conduct electricity better, according to a news release posted on UI's website on Friday.
While running printing experiments and flow simulations in lab, the researcher noticed that polymers go through two distinct phases of flow during printing: The first phase occurs when capillary action pulls on the polymer ink as it begins to evaporate, and the second phase is the result of the forces imposed by the printing blades and substrate, the researchers said.
They further uncovered another phase that occurs during printing in which the polymers appear to have vastly different properties. "This third phase occurs in between the two already-defined phases, and shows the polymers being stretched into planar shapes," said UI chemical and biomolecular engineering professor Ying Diao, who led the study.
Not only are the polymers stretched and flattened in this third phase, but they also remain that way after precipitating out of solution, making it possible to fine-tune printer settings to produce conjugated polymers for use in new, faster biomedical devices and flexible electronics.
"We are discovering a whole zoo of new polymer phases, all sensitive to the forces that take place during the printing process," Diao said. "We envision that these unexplored equilibria and flow-induced phases will ultimately translate into new conjugated polymers with exciting optoelectronic properties."
Conjugated polymers are formed by the union of electron-rich molecules along a backbone of alternating single and double chemical bonds. The conjunction allows electricity to travel very quickly through a polymer, making it highly desirable for use in electrical and optical applications. This mode of transporting charges works so well that conjugated polymers are now poised to compete with silicon materials.
The findings have been published in the journal Science Advances.