Amphiphilic Cyclodextrin-Modified Recycled Fibers for Green Hygiene Products with Enhanced Strength and Flushability

Abstract

People living in densely populated settlements face inadequate sanitation and rising incidences of acute bacterial infections, underscoring the urgent need for effective and sustainable hygienic products. The amphiphilic molecular architecture of β-cyclodextrin (β-CD), characterized by a hydrophobic internal cavity and a hydrophilic external surface, offers a unique platform for designing sustainable additives for hygiene products. This study employs β-CD to improve the mechanical performance and end-of-life management of old corrugated container (OCC)-derived recycled fibers for tissue and towel applications. β-CD operates through dual interactions: its hydrophobic cavity associates with lignin and other hydrophobic moieties via van der Waals interactions, while its hydrophilic exterior forms hydrogen bonds with cellulose, enhancing fiber–water interactions and hydrogen bonding. These coupled molecular interactions enhance dry strength while promoting fiber swelling, water penetration, and rapid disintegration, which is essential for flushability and recyclability. In dual-stage systems combining β-CD with low dosage of glyoxalated polyacrylamide (g-PAM), pretreated OCC (POCC) fibers achieved an immediate wet tensile comparable to g-PAM-only at a higher dosage while exhibiting substantially reduced disintegration time. Overall, this work demonstrates a viable pathway for producing recyclable and flushable recycled-fiber hygiene products that maintain high dry and immediate wet tensile strength during use, yet disintegrate rapidly during flushing or repulping.