Hydrophobization of Paper Using Organosilane and Titanium Dioxide Nanoparticles with Layer by Layer Method

Utilization of paper as packaging material and developing applied technological program on paper-based substrate are drastically dependent to control of cellulosic fiber hydrophilicity and to enhancement of its hydrophobic properties. Then this work carried out with the aim of developing hydrophobic surface on cellulosic fiber with layer by layer (LBL) method while keeping and enhancing the properties of paper network. The deposition was implemented by titanium dioxide nanoparticles and poly acrylic acid as cationic and anionic layer respectively on the fibers of unbleached hardwood Kraft pulp and using Zycosil and fluoroalkyl silane on the last layer. The hand-sheets were then made by this modified fiber. The contact angle and roughness were measured to evaluate the effect of layers on hydrophobicity. The results indicated that roughness increased with the number of layers. The instant contact angle was also increased with the number of layers and reached approximately to 110 degree at 7th layer. The dynamic contact angles dropped more lately with increasing the number of layers. The fluorosilane deposition as 8th layer in comparison with Zycosil showed more effect on surface energy reduction. The instant contact angle of Zycosil treated paper was measured 125 degree which dropped significantly to 48 degree after 30 seconds. However, fluorosilane modified paper exhibited contact angle of 140 degree at the same time. In addition, the presence of titanium dioxide nanoparticles on the surface of fiber was demonstrated by scanning electron microscopy (SEM) of paper surface.