PLA 'Performance Limitations' Overcome... Yonsei University and KAIST Synthesize High-Strength Eco-Friendly Plastic [Reading Science]

Ultra-Fast, Highly Selective Polymerization
Suggests Potential to Overcome Heat and Strength Weaknesses

A domestic research team has developed a new synthesis technology that can overcome the performance limitations of polylactide (PLA), a leading material in eco-friendly plastics. This achievement presents the possibility of improving the low heat resistance and mechanical strength that have been pointed out as weaknesses of conventional PLA, drawing attention to whether it can expand the scope of bioplastic commercialization.

The research team led by Professor Byungsoo Kim of the Department of Chemistry at Yonsei University, in collaboration with the research team led by Professor Yunmi Lee of the Department of Chemistry at KAIST, announced on March 20 that they have developed a technology that enables the rapid synthesis of PLA while precisely controlling its molecular structure by utilizing next-generation organocatalysts.

Schematic diagram showing the catalytic reaction and synthesized stereoblock PLA enabling both high reactivity and selectivity. Provided by the research team

PLA is an eco-friendly plastic that is manufactured from plant-based raw materials such as corn and sugarcane and is biodegradable. It is widely used for disposable cafe cups and packaging materials. However, compared to general petroleum-based plastics, PLA is vulnerable to heat and has low strength, which has limited its range of applications.

The core of this study lies in the precise control of the polymer's molecular arrangement. The research team succeeded in creating a 'stereoblock structure' in which the molecular chains of PLA are regularly arranged. Compared to a random arrangement, this structure increases the intermolecular bonding strength, thereby simultaneously enhancing both heat resistance and mechanical strength of the material.

In particular, the team succeeded in synthesizing high-performance PLA in just a few minutes by using racemic lactide monomers, which are relatively inexpensive and commercially readily available. Under room temperature conditions, the turnover frequency (TOF) reached up to 1,710 h-¹, demonstrating a reaction rate much faster than existing approaches. At low temperatures, the indicator for molecular regularity reached as high as 0.99, securing high selectivity. The team thus achieved both 'speed' and 'precision control,' which were difficult to accomplish simultaneously with existing catalyst systems.

"Molecular Arrangement Design Elevates Eco-Friendly Plastic Performance"

To verify the structure of the synthesized PLA, the research team, in collaboration with Professor Dooyul Ryu's team from the Department of Chemical and Biomolecular Engineering at Yonsei University, conducted X-ray scattering analysis. The results showed that the molecules formed a lamellar structure, with layers arranged in sequence, which is a structural feature that serves as a key factor in improving thermal and mechanical performance.

Photo of the research team. From the left: Byungsoo Kim, Professor of Chemistry at Yonsei University (corresponding author), Yoonmi Lee, Professor of Chemistry at KAIST (corresponding author), Sumin Lee, PhD candidate in Chemistry at Yonsei University (co-first author), Hoseung Lee, PhD candidate in Chemistry at KAIST (co-first author). Courtesy of Yonsei University

Professor Byungsoo Kim explained, "This study is significant in that we precisely controlled the polymer structure through catalysis and elucidated complex reaction mechanisms. It demonstrates the possibility of greatly enhancing the performance of eco-friendly plastics through molecular arrangement design."

He added, "PLA is a sustainable, biodegradable material with substantial potential for expansion into various fields in the future, not only packaging but also medical materials and more."

This research was conducted with support from the Mid-Career Researcher Program and the Nano-Material Technology Development Program of the National Research Foundation of Korea, funded by the Ministry of Science and ICT. The results were published online on March 4 in the international journal 'Angewandte Chemie International Edition,' issued by the German Chemical Society.

This content was produced with the assistance of AI translation services.