Comparing Isoelectric Point and Surface Composition of Plasma Modified Native and Deposited SiO2 Films Using Contact Angle Titrations and X‐ray Photoelectron Spectroscopy

Surface isoelectric point, contact angle (CA), chemical composition, film growth method, and aging effects were measured for plasma‐surface treatment of two different types of SiO2 substrates. The relationship between these values was explored using X‐ray photoelectron spectroscopy and CA titrations. Two plasma systems, Ar and H2O vapor inductively coupled rf plasmas were used to induce hydrophilic surface modifications on the SiO2 substrates. The SiO2 films deposited from a hexamethylsiloxane/O2 plasma were less susceptible to aging effects after plasma treatment than the native oxide layers. The stability of these surfaces is attributed to their relative thickness and mild annealing experienced during film formation. magnified image