Construction of super-hydrophobic paper surface using xylans as silica nanoparticle adsorbents

Abstract

Constructing super-hydrophobic surfaces with natural polymers is a major way to promote advanced and sustainable applications from traditional paper products. Among different types of natural polymers, xylan has advantages of abundance, easy separation, good water solubility/dispersibility, high affinity to paper fibers, good reactivity and unique rheological properties, making it a significant candidate. However, how to effectively assemble the water dispersible xylans and the water indispersible hydrophobic nano-particles onto hydrophilic paper surface has become a problem in super-hydrophobic surface construction. In this study, xylans were modified with dodecene succinic anhydride (DDSA) and hexadecene succinic anhydride to improve their hydrophobicity, which were then coated onto paper surface and used to adsorb silica nanoparticles in ethanol. A rough micro-nano structure was successfully fabricated on paper surface and a super-hydrophobic paper surface with water contact angle up to 157° was successfully obtained. The degree of substitution of the modified xylans has great influence on the super-hydrophobic surface construction. DDSA modified xylan with DS of ~ 0.2 has the highest affinity to silica nanoparticles and is able to construct super-hydrophobic paper surface after adsorbing silica nanoparticles. The super-hydrophobic paper surfaces have strong durability and maintain super-hydrophobicity after storing under room environment for 66 days or 100 times of surface friction. The superhydrophobic paper surfaces have good acidic stability but poor alkaline stability. This study promotes the research and applications of natural xylans in producing super-hydrophobic and other advanced paper products.