Superhydrophobic All-Cellulose Composite (ACC) via Hexadecyltrimethoxysilane (HDTMS) and HDTMS/Silica (SiO2)

All-cellulose composite (ACC) is a novel single polymer composite (SPC) that consists of cellulose for both reinforcing fiber and matrix phases. ACC has good mechanical, thermal, and optical properties due to compatibility of reinforcing fiber and matrix phases. However, abundant hydroxyl (OH) groups in the cellulose structures resulted in higher hydrophilicity of ACC, thus limiting the potential use in outdoor applications. In this study, ACC was fabricated using solvent infusion processing (SIP) from rayon textile with sodium hydroxide (NaOH)/urea solution to partially dissolve the cellulose fibers, followed by regeneration and drying processes. Subsequently, ACC was treated using two different coating solutions: (i) hexadecyltrimethoxysilane (HDTMS) and (ii) HDTMS/SiO 2 (silica). As a result, an efficient water repellency for HDTMS/SiO 2 -treated ACC was observed, showing a water contact angle of 159.3 ∘ , as compared to HDTMS-treated ACC with a water contact angle of 144.1 ∘ . However, a slightly higher water absorption of 52% was observed for HDTMS/SiO 2 -treated ACC, as compared to only 44% for HDTMS-treated ACC. Both treated ACCs showed smooth and homogeneous structures upon completion of the treatment.