Aerenchyma tissue of Juncus effusus L.: a novel resource for sustainable natural cellulose foams

The demand for sustainable, low-cost, and high-performance natural cellulose foams with isotropic structures has increased greatly due to growing environmental awareness. However, the synthesis of current cellulose foams/aerogels requires substantial amounts of energy and chemicals, mainly due to the challenges posed by the poor solubility and processability of raw cellulose derived from biomass resources. Consequently, these challenges further highlight the advantages offered by the direct utilization of natural cellulose foams, considering their economic and environmental benefits. Previous studies on natural cellulose foams have predominantly focused on specific plant components such as phloem, xylem, vascular vessels, fruits, and seeds. In this study, we present an overlooked alternative: the aerenchyma tissue of aquatic or wetland plants. Specifically, we investigated on Juncus effusus L. (JE), a commonly found problematic wetland weed that is known for its high reproductive ability, causing a reduction in annual forage yield. The aerenchyma tissue of JE was discovered to possess a well-developed 3D interconnected hierarchical structure, exhibiting remarkable properties as a natural lignocellulosic foam. These properties include exceptional compressibility, hydrophobicity (water contact angle: 147°), lightweights (density: 0.017 g/cm 3 ), and high porosity (98%). Through this study, we have introduced a novel natural cellulose foam and explored the utilization of biomass derived from wetland weed wastes.