Hydrophobicity modulation of glass and marble materials

Hydrophobic polymers applied on hydroxylated surfaces increase their durability against undesired weathering processes. The achievement of a certain degree of surface hydrophobicity (reducing the water permeation) constitutes one of the main research focuses.

For the study, two commercial Si-based resins, directly applied on both glass and Carrara marble substrates, and a silanisation process by using trichloromethylsilane (TCMS) were adopted. Contact angle measurements together with hysteresis determination and Surface Free Energy (SFE) were carried out to evaluate the hydrophobic features.

Drastic reduction of absorbed water

Hence, since only in the case of TCMS a good hydrophobicity was achieved (θ around 150°), two commercial polysiloxane-based additives were added respectively to the Si-based resins, according to their chemical compatibility. These auxiliary substances allowed to decrease the wettability features of either glass or marble. Furthermore, since all the investigated coatings could be used as stone materials protective agents, water capillary absorption and vapor permeability tests were performed. Also in this case, TCMS revealed to be the most performing one among the adopted silane-based resins, thanks to the drastic reduction of absorbed water and the decrease of vapor permeability within the threshold value of 50%.

The study can be found in Progress in Organic Coatings, Volume 136, November 2019.

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