SNU researchers develop nanopatterning technology for precise design and control of ‘disorder’

eoul National University College of Engineering announced that a research team led by Professor So Youn Kim of the Department of Chemical and Biological Engineering, in collaboration with Professor Su-Mi Hur’s team at DGIST and Professor S. Joon Kwon’s team at Sungkyunkwan University, has developed a methodology to precisely design and control the “degree of disorder” in nanopattern arrays using metal-infiltrated block copolymer (BCP) thin films*.

* Block copolymer (BCP): A polymer composed of chemically bonded chains of different types of polymers arranged in block structures.

This disordered nanopattern fabrication technology is regarded as an innovative approach that enables precise control of nanoscale disorder structures—previously difficult to regulate—thereby opening new possibilities in the design of nano-optical and nanoelectronic devices.

The research findings were published in April in the prestigious international journal Nature Communications. Notably, the study was selected for “Editors’ Highlights – Materials science and chemistry,” a curated collection of outstanding papers chosen by the journal’s editors, attracting attention from the global scientific community.

In ordered structures, waves propagate over long distances, whereas in disordered structures, repeated scattering can lead to localization, where waves remain confined within a specific region. Such disordered structures exhibit unique functionalities that can induce localization phenomena for various types of waves, including light, sound, and heat.

However, technical limitations have long hindered the reliable fabrication of disordered structures at the nanoscale and the quantitative control of their degree of disorder. In particular, previous BCP research has primarily focused on creating regularly ordered nanopatterns, with very few attempts to intentionally design disordered structures. Furthermore, defining “disorder” using a single metric has proven challenging, leaving reproducibility and quantitative control as unresolved issues.

These limitations have posed significant barriers to the commercialization of disordered structures in industrial processes and applications. Although such structures hold strong potential for applications in displays controlling light scattering, high-sensitivity sensors, energy conversion devices, and optical security technologies, their practical use has been hindered by difficulties in reproducibly fabricating identical structures over large areas, leading to performance variability. Therefore, achieving quantitative control and process reproducibility has been a critical prerequisite for commercialization.

To address these challenges, the joint research team successfully proposed a methodology for precisely designing and controlling the degree of disorder in nanopattern structures using a block copolymer–metal infiltration system.

The researchers first created centimeter-scale, uniformly ordered nanostructures using BCP thin films. They then introduced a gold (Au) precursor and varied thermal annealing conditions to induce a gradual transition from ordered to disordered structures. By employing rapid quenching using liquid nitrogen, they preserved the structures at each stage, enabling systematic observation of the disorder formation process.

Instead of defining disorder with a single parameter, the team developed a framework that quantitatively characterizes disorder by comprehensively analyzing positional and orientational changes of particles. This revealed that disordered structures are not simply “broken order,” but consist of multiple stages characterized by distinct positional and orientational variations.

In addition, through computer simulations, the team elucidated the mechanisms underlying the formation of disordered structures. They found that interactions between metal and polymer during annealing restrict molecular motion, playing a key role in stabilizing the resulting disordered configurations. By adjusting the infiltration ratio of gold (Au) and platinum (Pt), the researchers demonstrated precise and wide-range control over disorder—from highly ordered crystalline structures to liquid-like disordered states.

Furthermore, theoretical analysis of the functional properties of these structures revealed that heat and vibrational energy transport vary significantly depending on the type of disorder. This indicates that the approach enables not only fabrication but also the design of functional materials with tailored physical properties.

The highly reproducible disordered nanopattern fabrication technology developed in this study is expected to find broad applications in industries requiring low process variability and stable product performance. In particular, its application could expand to precision optical sensors, ultrathin optical devices, and nanostructures for thermal management. While conventional device design has focused on ordered structures, this new approach enables intentional design of disorder, allowing more flexible control of light and heat propagation.

Moreover, the technology could contribute to improved thermal management in electronic devices, reducing heat generation. It may also lead to thinner and lighter displays and optical components, enhanced image clarity, and more stable communication environments. Notably, the hyperuniform disordered structures identified in this study suggest strong potential as a foundational technology for next-generation optical materials capable of selectively controlling specific wavelengths of light.

Professor So Youn Kim of Seoul National University stated, “This study takes a counterintuitive approach by treating disorder not as a defect but as a design element. By combining the self-assembly properties of block copolymers with metal infiltration processes, we succeeded in reproducibly fabricating nanoscale disordered structures. This is particularly meaningful as it demonstrates the potential of this technology as a platform for developing wave-controlling devices.”

She added, “We plan to expand this research to various metal–polymer systems and continue advancing functional disordered nanomaterials.”

Sung Kwan Tae, an integrated M.S.-Ph.D. student in the Department of Chemical and Biological Engineering at Seoul National University, is currently conducting research as a visiting researcher at IMEC (Interuniversity Microelectronics Centre) in Belgium. Upon returning, he plans to continue experimental studies on the precise control and functionalization of disordered nanostructures.

This work is supported by the Samsung Research Funding Center for Samsung Electronics under Project Number SRFC-MA2201-02. (Project Title: Implementation of Nanostructured Organic Lattices with Topological Defects and Their Application in Phonon Localization Control)

□ Introduction to the SNU College of Engineering

Seoul National University (SNU) founded in 1946 is the first national university in South Korea. The College of Engineering at SNU has worked tirelessly to achieve its goal of ‘fostering leaders for global industry and society.’ In 12 departments, 323 internationally recognized full-time professors lead the development of cutting-edge technology in South Korea and serving as a driving force for international development.