Superhydrophobic, strong and transparent paper made from cellulosic fibers

Superhydrophobic and strong cellulosic paper was fabricated in a two-step process consisting of heavy refining and dip coating with PDMS (trimethylsiloxy-terminated poly (dimethylsiloxane)) and Hf-SiO₂ (hydrophobic fumed silica) solution. Results showed that the heavy refining produced extensive fibrillated fibers, which significantly increased the tensile strength. Meanwhile, the density of the paper sheet increased, and the porosity decreased. Benefiting from these changes, the subsequent dip coating operation was improved, producing paper with a very high water contact angle (WCA), yet with a low up-take of the hydrophobic solution. Finally, superhydrophobic paper sheets were fabricated with 155^o WCA and 1^o sliding angle (SA). At the same time, its tensile strength increased by 12.7 fold (from 0.85 MPa of the original paper to 10.8 MPa), with additional benefits, such as high transparency (75% at 550 nm). The superhydrophobic and strong paper is highly desirable for high value-added utilization of fiber.