Polymethylsilsesquioxane powder prepared by morphology-controlled growth
The incompatibility of superhydrophobic particles with waterborne latexes impedes the direct mixing of them to make mixtures for superhydrophobic coatings fabrication.
Polymethylsilsesquioxane (PMSQ) prepared by methyltrialkoxysilane precursors can change from hydrophilic to hydrophobic with the increased degree of condensation. This property makes PMSQ suitable for compounding with waterborne latexes for highly hydrophobic coatings fabrication.
A new work presents a method for the morphology control of PMSQ to make highly porous PMSQ particles with micro-/nano-roughness on the surface. A gel of PMSQ was first prepared in aqueous medium and broken into small pieces by a high speed homogeniser; additional acid-catalysed hydrolyzate of methyltrimethoxysilane was added to this dispersion of broken particles.
Superhydrophobic coating after drying
The following base-catalysed regrowth of PMSQ on the preformed gel skeleton gave highly porous PMSQ powder suitable for compounding with water-borne latexes. The composite of PMSQ wet powder and a styrene-acrylate water-borne latex gave a superhydrophobic coating after drying in ambient condition, of which the water contact angle reaches 153.1° and sliding angle is low to 28.7°.
The study has been published in Journal of Coatings Technology and Research, September 2019, Volume 16, Issue 5.