Abstract:

Objective Superhydrophobic materials have a wide range of applications with their unique properties. However, the preparation often involves fluorine-containing materials, organic solvents, an so on, which are expensive and cause pollution, seriously limiting their applications. Therefore, it is important to develop environmentally friendly and low-cost materials to prepare superhydrophobic materials through simple preparation processes.

Method Porous carbon based on bagasse was prepared by high-temperature carbonization and activation. After pretreatment (80 ℃, drying for 12 h), bagasse was calcined at 650 ℃ for 20 min under N₂ flow to obtain carbonized bagasse (CB). Different proportions of CB and KOH were mixed and grinded, and the mixture was then heated in a nitrogen atmosphere to activate CB. The obtained black particles were washed with HCl and deionized water and dried at 80 ℃ to prepare bagasse-based porous carbon (BPC). The prepared BPC and low surface energy substance polydimethylsiloxane (PDMS) were applied to cotton fabric, which is a process known as BPC/PDMS treatment of cotton fabric.

Results The BPC was fabricated via a high-temperature carbonization method, achieving a remarkable specific surface area of 1 614.25 m²/g. Notably, the BPC-800 ℃ exhibited a high degree of graphitization with an I_D/I_G ratio of 0.76. When the activation temperature was set at 700 ℃ and the BPC to KOH ratio was 1∶4, the BPC surface displayed an optimal rough structure with an abundant microporous network. By employing a simple impregnation method, the prepared BPC and the low surface energy substance PDMS were coated onto the cotton fabric, resulting in the BPC/PDMS treatment of cotton fabric. The influence of varying BPC and PDMS concentrations on the hydrophobic properties of the finished fabric was investigated and the results revealed that the surface contact angle of the BPC/PDMS cotton fabric peaked at 162.2° when the PDMS concentration was 3% and the BPC concentration was 0.2%. The combination of BPC and PDMS imparted the fabric with a rough surface, crucial for achieving superhydrophobic properties. Additionally, due to the adhesive nature of PDMS, it was observed that the BPC particles were firmly encapsulated on the cotton fabric surface by PDMS, successfully constructing a superhydrophobic surface. The TGA curve revealed that when the temperature reached 700 ℃, the residual percentage of the BPC/PDMS treatment of cotton fabric was 16.59%, 40 times higher than that of untreated cotton fabric. This was primarily attributed to the incomplete decomposition of BPC and PDMS, confirming the successful preparation of the superhydrophobic cotton fabric. As a result, the BPC/PDMS treatment of cotton fabric exhibited water repellency and a "silver mirror" effect. The water contact angles of the untreated and BPC/PDMS cotton fabric were 0° and 162.2°, respectively. Furthermore, water, cola, juice, milk, and coffee droplets remained spherical on the surface of the BPC/PDMS treatment of cotton fabric, while they spread rapidly on the untreated fabric. These results indicate that the BPC/PDMS treatment of cotton fabric achieved remarkable water and stain repellency. When the fabric was placed onto a slide and positioned inclined, methyl blue and purple chalk powder were uniformly sprinkled on the fabric surface followed by rapid rolling water droplets. Notably, both the methyl blue and purple chalk powder were completely removed from the surface, leaving no trace of contaminants. This outstanding performance demonstrates the excellent self-cleaning capabilities of the superhydrophobic cotton fabric.

Conclusion The preparation of bagasse-based porous carbon (BPC) was thoroughly examined. Notably, when the activation temperature was set at 700 ℃ and the ratio of BPC to KOH was 1∶4, the resulting BPC achieved a significant specific surface area of 1 614.25 m²/g, along with a high degree of graphitization. Furthermore, its surface exhibited a coarse texture with a substantial micropore distribution. To impart superhydrophobicity to cotton fabric, BPC and polydimethylsiloxane (PDMS), a low surface energy material, were applied to the fabric. This combination of microscopic roughness and low surface energy materials is crucial for achieving superhydrophobicity. The successful loading of BPC and PDMS onto the cotton fabric was confirmed. When the PDMS concentration was set at 3% and the BPC concentration at 0.2%, the water droplet contact angle on the BPC/PDMS treatment of cotton fabric reached an impressive 162.2°, demonstrating excellent superhydrophobicity. Additionally, cola, water droplets, milk, and fruit juice remained spherical on the surface of the BPC/PDMS treatment of cotton fabric, indicating its remarkable self-cleaning, stain resistance, and water repellency properties.

Key words: sugarcane bagasse based porous carbon, polydimethylsiloxane, superhydrophobicity, cotton fabric, self-cleaning performance, waterproof and anti-fouling performance