Durability and photocatalytic activity of superhydrophobic gypsum boards coated with PDMS/MTCS-modified SiO2-TiO2 NPs

A hybrid of superhydrophobic and self-cleaning functions was successfully produced on a commercial gypsum board by spray coating with SiO2-TiO2 nanoparticles (NPs) modified with various mixture ratios of polydimethylsiloxane (PDMS) and methyltrichlorosilane (MTCS). PDMS/MTCS with a ratio of 75/25 was found to be the optimum condition. Interestingly, the coated gypsum board not only exhibits a superhydrophobic property but also photocatalytic activity compared with unmodified SiO2-TiO2 NPs. Moreover, the superhydrophobic gypsum board can resist impinging water over 60,000 drops, indicating the good mechanical stability of the coating. The durability of the coating was tested under dust particle accumulation, sand abrasion impact and water jet impact tests. Thus, the NP coating with PDMS/MTCS with a mixture ratio of 75/25 plays an important and promising role in future industrial and self-cleaning applications.