If we were to rewind time, nobody would have predicted that this girl from the secluded mountainous region would traverse through Tsinghua University, the Massachusetts Institute of Technology (MIT), and Stanford University, eventually becoming a professor at the Beckman Institute for Advanced Science and Technology at the University of Illinois, USA. She seamlessly transitioned between different fields such as chemical engineering, pharmaceuticals, flexible electronics, and polymer self-assembly, imprinting her name on the pages of top-tier international academic journals.
Recently, Diao Ying published her latest research breakthrough in the Proceedings of the National Academy of Sciences of the United States of America (PNAS): a novel technique called "Single Ink 3D Printing with Multiple Colors".
The imagery accompanying the media coverage of her achievement is striking: an adorable little chameleon, transitioning in color from fluorescent yellow to grassy green, then shimmering into a luminous midnight blue. Much like Diao Ying's own life trajectory, it's vibrant and naturally evolving.
The chameleon printed by Diao Ying's team. Image source: Diao Ying's team paper "Direct-Ink-Write Crosslinkable Bottlebrush Block Polymers for On-the-fly Control of Structural color"
Bringing Childhood Dreams to Life with Structural Color
During her youth, Diao Ying frequented natural history museums, marveling at the vibrant wings of butterflies and their microscopic structures under the microscope. She noticed that unlike the colors of clothing, paintings, or flowers, the beauty of butterfly wings was exceptionally dynamic, exhibiting different colors and sheens under varying light and angles. The term "iridescent," perhaps, best describes such beauty.
As she grew older, Diao Ying learned about a term: structural color. The colors we see can be categorized into two main types: chemical pigment colors and physical structural colors. The colors displayed on peacock feathers, butterfly wings, and chameleon skin are typical examples of structural colors. Unlike static chemical pigment colors (which are based on molecules selectively absorbing light), structural colors are produced by the interaction of micro-nano physical structures with natural light through scattering, interference, diffraction, and other phenomena. Most things that can "change color" possess structural colors.
Diao Ying was captivated by the magical properties of structural colors, stating, "Studying structural color has been a dream of mine since childhood."
And the paper published in PNAS was inspired by the chameleon.
"The ink material we designed is just like a chameleon," explained Diao Ying to China Science Daily. The material is a crosslinkable bottlebrush block copolymer solution (c-BBCP) that can be crosslinked by light, forming a brush-like surface capable of forming layered structures.
When this material is extruded as ink from a 3D printing nozzle, the structures in the ink undergo self-assembly driven by evaporation, resulting in continuously thickening layers. Different thicknesses of structures exhibit different structural colors under white light. If no additional intervention is made, the color changes from blue to red as the ink evaporates from solution to solid. If ultraviolet (UV) light is introduced during this process, the color will be fixed. Diao Ying's students also discovered that the fixed color depends on the intensity of UV light exposure.
After numerous experiments, Diao Ying's team, based on this principle, improved and designed a direct ink writing 3D printing device capable of UV irradiation. Thus, by dynamically adjusting the UV irradiance during 3D printing, a single color can be transformed into a colorful spectrum. The chameleon we see is printed in this way.
Effectively controlling 3D printing at the microscopic level has always been a technical challenge. However, the new technology developed by Diao Ying's team not only achieves structural self-assembly control at the nanometer scale but also enables colorful structural color printing, making it a pioneering technology in the field of 3D printing.
What's more gratifying to Diao Ying is that this is also an environmentally friendly "sustainable" technology. She recalls childhood memories tainted by the sight of billowing black smoke and choking odors from coal burning in winter. Thus, she has always hoped that through her research, she could contribute to environmental protection efforts.
The polycyclic aromatic structures in traditional chemical dyes lead to serious water pollution. In contrast, structural colors, compared to dye colors, do not rely on polycyclic aromatic structures, which helps achieve sustainable development in related industries and reduce the costs of environmental protection.
Currently, color change only occurs during the printing process; once printing is completed, the color cannot change further. Diao Ying looks forward to continuing to develop more advanced structural color technologies, such as creating truly color-changing materials.
"Imagine pulling your clothes or bending over, changing the molecular assembly structure, and the color of the clothes changing. Would this affect fashion and aesthetics?" she said with a smile. "Or, combining color-changing materials with artificial intelligence technology, perhaps we can also have clothing that changes color like chameleons in response to the environment."
Brainstorming Sparks Inspiration
The inspiration for this work came during a brainstorming session with Diao Ying and several colleagues while applying for funding from the US National Science Foundation.
At the University of Illinois, the idea of "valuing teamwork" is ingrained. "The school particularly encourages everyone to come together, with a dozen or twenty different professors from different disciplines collaborating to realize those crazy ideas, those high-risk, high-reward ideas. Because many times, these ideas can only be realized when people come together, and no one can achieve them alone," Diao Ying excitedly explained.
This research was completed through the collaboration of four researchers. Damien Guironnet designed the material; Diao Ying modified the 3D printing technology; Simon Rogers measured the speed of molecular assembly through experiments; and Charles Sing explained the self-assembly mechanism through computational simulations.
"Like the Eight Immortals crossing the sea, each one showing their unique skills — the four of us working together not only invented new technology but also created new materials, proposed new mechanisms, and developed new concepts," Diao Ying proudly stated.
Dr. Diao Ying mentors doctoral students. In response to a question about sharing research experiences, she spontaneously exclaimed, "Playfulness!"
"It's like a child playing outside. You need that spirit of free exploration and curiosity to discover new phenomena and make breakthroughs," she said.
"Free exploration" and "interest" appeared multiple times in Diao Ying's narrative during the short interview, describing not only her research experiences but also her life attitude.
Colorful and Varied Remarkable Resume
Diao Ying's academic career is impressive.
Her hometown is the remote forest area of Jagdaqi District in the Greater Khingan Mountains. Located within the Ergun City, Hulunbuir, Inner Mongolia Autonomous Region, it is administratively part of the Daxing'anling area of Heilongjiang Province, giving rise to a unique geographical and cultural phenomenon known as an "enclave."
Growing up in a remote mountainous area, Diao Ying was not familiar with the outside world until she attended high school, when her outstanding performance caught the attention of the renowned teacher Qu Anjun from Daqing Tie Ren High School, who invited her to participate in physics competitions. With excellent grades in the college entrance examination, she entered the Department of Chemical Engineering at Tsinghua University.
From that moment on, her life trajectory completely changed.
Diao Ying has always been interested in mathematics and science, which guided her continuous exploration in the academic field.
After graduating from Tsinghua University, she entered the Massachusetts Institute of Technology (MIT), where she obtained her doctoral degree. At that time, she was studying pharmaceuticals, but during her doctoral studies, the renowned Chinese-American female scientist and Stanford University professor Zhenan Bao came to MIT to give a lecture on electronic flexible materials, sparking Diao Ying's deep longing. Shortly after the lecture, Diao Ying contacted Professor Bao and became a postdoctoral fellow in her laboratory after an interview.
"Professor Bao accepted me, a cross-disciplinary student. She believed that my different perspectives could bring new ideas to the field of flexible electronics," Diao Ying recalled.
From chemical engineering to pharmaceuticals, and then to electronic flexible materials, Diao Ying's versatile life journey continues. After joining the Beckman Institute for Advanced Science and Technology at the University of Illinois, she immersed herself in research on polymer self-assembly and printing. Frequently changing research fields did not hinder her progress. In 2021, she was promoted to associate professor at the University of Illinois, and in 2023, she was honored with the title of "University Scholar" at the University of Illinois.
Diao Ying has been awarded the prestigious title of "University Scholar" at the University of Illinois. Her team celebrated the achievement with her and took a commemorative photo together. With a resume like hers, it's akin to a smoothly transitioning, color-shifting 3D printing masterpiece, gracefully spiraling upward, chasing after her passions and dreams, painting a vibrant and beautiful life.
She says with a smile, "If you want to do something, you can make it happen; if you want to learn, you can learn."
The starry sky image printed using 3D technology by the Diao Ying team. Image provided by the interviewee. For more details, please refer to the related paper: Link to Paper
