In an elegant fusion of art and science, researchers at Rice University have achieved a major milestone in nanomaterials engineering by uncovering how boron nitride nanotubes (BNNTs) — touted for their strength, thermal stability and insulating properties — can be coaxed into forming ordered liquid crystalline phases in water. Their work, published in Langmuir , the premier American Chemical Society journal in colloid and surface chemistry, was so visually striking it graced the journal's cover.
That vibrant image, however, represents more than just the beauty of science at the nanoscale. It captures the essence of a new, scalable method to align BNNTs in aqueous solutions using a common bile-salt surfactant — sodium deoxycholate (SDC) — opening the door to next-generation materials for aerospace, electronics and beyond.
"This work is very interesting from the fundamental point of view because it shows that BNNTs can be used as model systems to study novel nanorod liquid crystals," said Matteo Pasquali , the A.J. Hartsook Professor of Chemical and Biomolecular Engineering, professor of chemistry, materials science and nanoengineering and corresponding author on the study. "The main advantage is that BNNTs are relatively transparent and easily studied via visible light unlike carbon nanotubes , which form dark liquid crystals that are hard to examine via light microscopy."
For first author Joe Khoury , the study was more than routine science. Trained as an architect in Syria, he transitioned to chemical engineering after moving to the U.S., but his background in visual design may have helped him see something others might have missed. During a routine purification step, he noticed that as water was filtered from the dispersion, the leftover material became thick and glowed under polarized light — a hallmark of liquid crystal formation. Inspired by this observation, the team hypothesized that increasing the SDC concentration would drive BNNTs to self-assemble into ordered nematic phases.
To test their hypothesis, the researchers conducted a meticulous series of experiments, preparing BNNT-SDC dispersions at varying concentrations. They used polarized light microscopy to observe the transition from disordered states to partially ordered and then fully ordered liquid crystalline phases. Cryogenic electron microscopy provided high-resolution confirmation of BNNT alignment.
Crucially, they produced the first comprehensive phase diagram for BNNTs in surfactant solutions — a predictive map that allows scientists to anticipate how BNNTs will behave at different concentration ratios.
"No one had done this before," Khoury said. "Previous studies either worked at low BNNT concentrations or used too little surfactant. We showed that if you increase both in the right proportion, you can trigger liquid crystalline ordering without using harsh chemicals or complicated procedures."
In addition to mapping phase behavior, the team followed a simple, reproducible method to turn these dispersions into thin, well-aligned BNNT films. Using a specialized blade to shear the material onto a glass slide, they fabricated transparent, robust films ideal for thermal management and structural reinforcement applications (think lighter, stronger and more heat-tolerant components in tech devices or aircraft). Using X-ray diffraction and electron microscopy, the team confirmed the alignment at the nanoscale level.
"We demonstrated that nematic alignment in solution can be preserved and translated into solid films ," Khoury said. "That makes this a highly scalable platform for next-gen materials."
The study lays the groundwork for new research into lyotropic liquid crystals formed from nanorods. Its simplicity — no strong acids, no harsh conditions — makes it accessible to labs worldwide. And its implications stretch from theoretical physics to commercial materials engineering.
"This is just the beginning," Pasquali said. "With this road map, we can now explore how to fine-tune BNNT alignment for specific applications. It's not just about making films; it's about understanding a whole new class of functional nanomaterials."
Pasquali added that the beauty of the images was mesmerizing.
"When Joe sent me candidate images for the cover, I felt like I was looking at paintings by Dali or Van Gogh," Pasquali said. "The cover image could be the tower of Barad-dur from 'The Lord of the Rings' painted by a surrealist artist."
Khoury added that this research would not have been possible without the guidance and mentorship from his team and co-authors, including Pasquali; Angel Martí , professor and chair of chemistry and professor of bioengineering and materials science and nanoengineering at Rice; Cheol Park of NASA Langley Research Center; Lyndsey Scammell from BNNT LLC; and Yeshayahu Talmon at the Technion-Israel Institute of Technology, among others.
This research was supported by the Welch Foundation, BNNT LLC, the Technion Russell Berrie Nanotechnology Institute and Rice's Electron Microscopy Center and its Shared Equipment Authority.
