Facile Preparation of AZO-Functionalized Cotton Fabrics With High Infrared Reflectance via a Conventional Pad–Dry–Cure Process

Abstract

Passive personal thermal management textiles with effective infrared (IR) shielding are highly sought after for outdoor cooling purposes. Herein, we report an application-driven paradigm utilizing aluminum-doped zinc oxide (AZO) nanoparticles on cotton knitted fabric via a conventional pad–dry–cure process. The AZO dispersions were optimized with anionic dispersant BYK-190, while polyurethane dispersion (PUD) 1087R3 was chosen as the ideal binder. Optimal conditions were identified as an AZO particle size of 100–500 nm, an AZO concentration of 7.5 wt%, and a PUD 1087R3:AZO mass ratio of 1:1. The resulting AZO-finished cotton fabric demonstrated a high IR reflectance of about 80%, achieved primarily through free-carrier plasma reflection of AZO nanoparticles. As a result, the fabric's surface temperature decreased by 11.4°C under an IR lamp and, importantly, by 4.4°C under direct summer sunlight compared to unfinished cotton knitted fabric. Additionally, the fabric retained excellent wearability. This study offers a straightforward, scalable, and effective approach for developing high-efficiency cooling textiles, with significant potential for applications in summer outdoor wearables and personal thermal management systems.