6/23/2023 0 Comments Pdms si2p xps peakDeconvolution of the O 1s and Si 2p XPS peaks were performed to determine contributions from bridging and nonbridging atoms. Samples with a water-to-cement ratio (w/c) of 0.5 showed a larger change in contact angle than 0.4 w/c ratio samples, because of a greater number of hydroxyl groups at the surface. Relative to untreated samples, APTES samples decreased the contact angle, PDMS samples increased the contact angle, and GPTMS did not show a significant change in contact angle. These silanes have different end groups, so the change in surface energy after undergoing a successful reaction between the silane and hydroxyls on the surface of the cement paste was demonstrated by a change in contact angle. Three different silane coupling agents were investigated: aminopropyltriethoxy silane (APTES), 3-glycidyloxypropyltrimethoxy silane (GPTMS), and methoxy-terminated polydimethxyl siloxane (PDMS). X-ray photoelectron spectroscopy (XPS) and static contact angle measurements were used to study the interaction between silane coupling agents and cured cement paste.
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