Molecular dynamics simulations are used to study the structural properties of mixed self-assembled monolayers (SAMs) of 11-carbon alkanethiolate chains, comprising methyl-terminated and carboxylic acid-terminated tail groups, coating a planar gold surface and interfaced with water. Three different arrangements of the SAM-coated surfaces are compared, namely: random, ordered and Janus particles-type shells. Our simulation study reveals the different structural morphology of the SAM surfaces and shows how it influences their overall hydrophilicity, the hydrogen-bonding structure and the water molecules orientation.