Preparation of waterborne self-cleaning nanocomposite coatings based on TiO2/PMMA latex

Titania/poly(methyl methacrylate) core/shell (TiO2/PMMA) latex was synthesized by miniemulsion polymerization and further mixed with modified colloidal silica to create waterborne nanocomposite coatings (M-SiO2/TiO2/PMMA). The coatings were undergone accelerated weathering tests and their surface wettability, transparency, and morphology were monitored as a function of weathering time. Super-hydrophilic surfaces were attained after 27-34h aging, being attributed to the unique distribution of TiO2 nanoparticles in PMMA phase. In contrast to the coating based on the mixture of M-SiO2, TiO2 nanoparticles, and PMMA latex, this time is quite short and absolutely benefit for their outdoor application. Due to the degradation of organic matrix, transparency reduction and film thickness loss of coatings took place in weathering tests. Nevertheless, these undesired evolutions can be alleviated by decreasing film thickness or using adequate quantity of TiO2/PMMA latex. Photodegradation experiments of methyl blue indicate that the formed superhydrophilic coatings are excellent in self-cleaning performance. (C) 2015 Elsevier B.V. All rights reserved.