Universal Strategies To Fabricate Superhydrophobic Sufaces On Different Substrates Based On Polydopamine

With the continuous development of micro-/nano- technology and the rise of bionics research, superhydrophobic materials have attracted wide attention. Due to its special surface wettability, superhydrophobic materials hold great prospects for wide applications in daily life, transportation and the construction of national defense. There are many different ways to fabricate superhydrophobic materials; however, universal strategies to fabricate superhydrophobic surfaces(coded as SHS) on different substrates are rare. In this thesis, several universal strategies to fabricate SHS have been developed based on polydopamine(coded as PDA), which can be adhered strongly to a wide range of substrates(including silicon wafer, titanium alloy plate, and polypropylene sheet,coded as Si, Ti, and PP, respectively) and further chelate with nanoparticles in the solution to form rough adlayer. The surface morphology, surface chemical composition,surface wettability, and stability of the so-prepared samples are characterized. The main contents are as follows:1. Based on copper plating on PDA and further surface passivation, SHS were farbicated on different substrates of Si, Ti, and PP. Specifically, taking advantage of the strong adhesive properties of PDA, Si substrate was pre-coated with PDA; then, copper was plated thereon due to the chelating properties of catechol moieties on PDA; finally,the so-plated copper was passivated by 1-dodecanethiol(coded as DT). Static contact angle and sliding angle of the so-obtained SHS on Si were measured to be 157.83° and5°, respectively. Further experimental results showed that the micro-/nano- composite surface structure and inert chemical nature are key factors to form SHS. The stability of so-obtained SHS was also investigated. Specifically, the change in superhydrophobicity was not obvious after being UV irradiated for 12 h or exposing to air condition for 2months. This so-developed method was quite universal and can be applied to other substrates, such as Ti, and PP.2. Rough silver structures were fabricated on the PDA-coated Si substrate by the replacement reaction between AgNO3 and the plated copper. After further surface passivation with DT, SHS with SCA of 164.26° and SA of 3° was fabricated successfully. Compared with the method of copper plating / DT modification, this method was more time-saving and the so-obtained SHS was more stable. Spefically,after UV irradiation for 5 days or exposing to air conditions for 2 months, the change insuperhydrophobicity is not obvious. This so-developed method was quite universal and can be applied to other substrates, such as Ti, and PP.3. Taking advantage of silver mirror reaction, SHS were farbricated on the substrates modified by PDA. Specifically, the Si substrate was pre-coated with PDA;then, silver nanoparticles generated by silver mirror reaction in the aqueous solution were chelated onto the PDA surface; finally, the surface was passivated by DT molecules. Static contact angle and sliding angle of the so-obtained SHS on Si were measured to be 163.70° and 2°, respectively. The stability of so-obtained SHS was also investigated. The change in superhydrophobicity was not obvious after being UV irradiated for 7 days or exposing to air condition for 2 months. Compared with the methods of copper plating / DT modification or copper plating / silver deposition by replacement reaction between AgNO3 and copper / DT modification, this method was much simpler. Moreover, this so-developed method was quite universal and can be applied to other substrates, such as Ti, and PP.