KAIST

<(From left) (Top to bottom) Professor Jaewook Myung of the Department of Civil and Environmental Engineering, Dr. Shinhyeong Choe, Ph.D candidate Yongjun Cho, M.S candidate Hoseong Moon, (Center) Ph,D candidate Pham Thanh Trung Ninh>

Fallen leaves, which were discarded every year, have been transformed into a resource that can replace waste plastics, a major nuisance in rural areas. A research team at our university has developed biodegradable agricultural vinyl made from fallen leaves, presenting a new way to solve the problem of conventional plastic vinyl, which has been pointed out as a cause of soil pollution.

KAIST announced on April 30th that a research team led by Professor Jaewook Myung of the Department of Civil and Environmental Engineering developed an eco-friendly agricultural mulch film (an agricultural vinyl that covers the soil to suppress weeds and maintain moisture) that decomposes in the ground using fallen leaves collected from the campus and near the Gapcheon River in Daejeon. This research is significant in that it converted fallen leaves, which are non-edible biomass (plant resources not used for food) that were discarded as useless, into high-value functional materials.

Mulch films, widely used in agricultural fields, are essential materials for suppressing weed growth and maintaining soil moisture. However, most films currently used are made of polyethylene (PE, a representative petroleum-based plastic), making them difficult to collect after use. Residuals left in the soil turn into microplastics (plastic particles so small they are invisible to the naked eye), causing environmental pollution.

To extract key components from fallen leaves, the research team utilized a Hydrated Deep Eutectic Solvent (DES, a special eco-friendly solvent with low toxicity) that mixes citric acid and choline chloride.

Through this, they extracted nanocellulose (plant-derived nanofibers with high strength and eco-friendliness) obtainable from plant cell walls and combined it with polyvinyl alcohol (PVA, a water-soluble and naturally degradable polymer material) to produce a composite film. In particular, the eco-friendliness was further enhanced by performing all manufacturing processes based on water instead of harmful organic solvents.

The "fallen leaf film" developed in this way showed sufficient performance even in actual agricultural environments. As a result of the experiment, it effectively blocked ultraviolet rays (UVA and UVB) and exhibited moisturizing performance that suppressed soil moisture loss to a level of about 5% for 14 days. In addition, ryegrass grown using this film showed better growth status than cases where no film was used.

<Figure 1. An eco-friendly strategy that upcycles low-utilization fallen leaves into biodegradable mulching film for natural soil, along with the concept of applying sustainable plasticulture.>

<Figure 2. A schematic diagram of the fabrication process and self-assembly mechanism by which a mulching film is formed through complex hydrogen-bonding interactions>

Biodegradation performance was also confirmed. As a result of testing under soil conditions, the developed film decomposed by 34.4% in about 115 days, showing a faster decomposition rate than conventional biodegradable films. Furthermore, it was confirmed that plant toxicity (harmful effects on plant germination or growth) did not occur during the decomposition process, thus not affecting the germination and early growth of ryegrass and bok choy.

Professor Jaewook Myung said, “This research is meaningful in that it went beyond simply processing fallen leaves and converted them into functional materials that can protect the agricultural environment. Through the use of fallen leaves that do not compete with food resources and water-based processes, it can be utilized as a sustainable alternative technology for agricultural plastics.”

This research was participated in by Pham Thanh Trung Ninh, a PhD student in the Department of Civil and Environmental Engineering, as the first author. The research results were published on February 6, 2026, in ‘Green Chemistry,’ an international academic journal in the fields of chemistry and environment, and were selected as the journal’s inside front cover.

※ Paper Title: All-water-based fabrication of biodegradable mulch films from dead leaves via complex hydrogen-bonded networks, DOI: 10.1039/d5gc06616f (Author Information: Pham Thanh Trung Ninh (KAIST, First Author), Shinhyeong Choe (KAIST), Yongjun Cho (KAIST), Hoseong Moon (KAIST), Jaewook Myung (KAIST, Corresponding Author) total of 5 persons)

<Figure 3. The inside front cover page of the latest issue of the Green Chemistry journal>

Meanwhile, this research was conducted with the support of the Excellent Young Researcher Program of the National Research Foundation of Korea under the Ministry of Science and ICT and the KAIST Grand Challenge 30 project funds.