Effect of ageing on wettability of quartz surfaces modified by Ar implantation

Abstract

Ion implantation is a powerful technique to modify the contact angles of surfaces. However, a change of the contact angle with the passage of time, called ageing, is observed on most surfaces. This paper aims to better understand the mechanism leading to the ageing of quartz surfaces implanted by argon ion. Coupons of quartz have been irradiated by 3 keV Ar ions to a fluence of 1.8×1016 Ar cm−2. Some implantations were performed under oxygen partial pressure (∼5×10−5 Torr). The samples have been characterized at different periods of time after implantation by means of contact angle hysteresis measurements, angle resolved x-ray photoelectron spectroscopy (ARXPS) and lateral force microscopy (LFM). A more hydrophilic surface was observed immediately after implantation. This effect was strongly enhanced by the use of an O2 partial pressure. With the passage of time, the contact angles increased both in ambient air as well as under an Ar atmosphere. Characterization by means of XPS has shown a decrease of the relative concentrations of the more polar molecules containing oxygen (C–O, C = O and (O–C = O)–O) which could partly explain the increase of the contact angles with time. On the other hand, a higher ratio of the signals SiO2(104 eV)/SiO2(103 eV) is observed for samples implanted with O2which could be responsible for their higher level of wettability. A model using the ARXPS measurements suggests that for the samples implanted without oxygen, the ageing could also be caused by the spreading of a natural carbonaceous surface layer dispersed into islands after the Ar implantation. This layer being more hydrophobic than the SiO2 surface, its spreading would increase the contact angles. Characterization by means of AFM–LFM shows that the surface is composed of two areas having different friction properties. Their distribution is in agreement with the covered surface fraction given by the model for the samples implanted without oxygen and aged in Ar.

Retention forces and contact angles for critical liquid drops on non-horizontal surfaces

“…Nevertheless, it was tested against independent measurements of contact angles at general conditions. Measurements of θ A and θ R were obtained from 14 sources in the open technical literature [5,8,[16][17][18][19][20][21][22][23][24][25][26][27], covering a wide variety of liquids and surfaces, including different liquid compositions and surface conditions. Data for ultra-hydrophobic surfaces were also included, although they fall outside the applicable range of the current model.…”

Low temperature silicon oxide deposition on polymer powders in a fluidized bed coupled to a cold remote plasma

“…Especially for run S5, the contact angle quickly rises from very low values and stabilizes at about 50°. This evolution could be due to the spreading of a hydrophobic carbonaceous contamination-layer on the silicon oxide film, as demonstrated by Ross et al [45]. In their case, the aging of quartz after ion implantation was studied.…”

“…As PE is hydrophobic, this trend can explain the variations of the contact angle. The very low contact angle obtained for run S5 is then due to the complete coverage of the powders by a low contact angle silicon oxide (for instance, the contact angle of quartz is 38° [45]) and to the presence of silanol groups at the surface. So, depending on the operating conditions, the growth process can lead either to discontinuous coated zones or to a complete coverage of the powder.…”

Investigation into time dependant degradation and atmospheric conditions on the wettability of nylon 6,6 which has undergone CO2 laser surface modification

“…Time (Weeks) Most work [25,26,31] focuses on the variation of contact angle over 28 days and does not consider any long term effects post-28 days. This could be of some significance as it can be seen through Figures 6 and 7 that the contact angle dramatically decreases for all samples after the 4 week hydrophobic recovery period.…”

“…A number of various long term studies have been carried out investigating the effect of different parameters on the wettability of a material over a set amount of time [23][24][25][26]. In addition to long term studies it has also been observed that the differing atmospheric pressure and differing environments can have a major effect on the wettability of a material as seen by Li et al [27], Hansen et al [28] and Siemons et al [29].…”