Breadcrumbs Section. Click here to navigate to respective pages.
Chapter
Chapter
The non-dispersive interaction energy between glass and water as a function of pH is expected to reflect the surface charge generated by the exposed chemical functions on the clean glas s surface. The variations in surface charge, generated by the exposed SiOH and aluminum oxide groups, is expected to give rise to fea-tures representing the surface chemistry of the clean glass. The scatter i n the data shown in Figures 4 and 5 allows only general trends to be discerned. The p.z.c.'s at pH 3 and 9 have been described in the preceding paragraphs. It is interesting to note that the chromic acid cleaned glass surfaces behave in a similar manner, showing virtually identical trends. The pyrolysis cleaned glass surfaces show dif-ferences in their behavior across the different glass compositions. These trends correlate with those observed for organic contamination of these surfaces, as de-scribed in Section 3.1, where the chromic acid cleaned glass surfaces all showed similar behavior, while the pyrolyzed glass showed significant differences in its sensitivity to contamination. In particular, the pyrolyzed silica surface shows far lower non-dispersive interaction energy with water than the pyrolyzed Corning code 1737 or sodalime glasses. This features correlates with the high degree of adsorbed contamination, described in Section 3.1, for the pyrolyzed silica surface. The datum in Figure 5 for the non-dispersive interaction energy between a py-rolyzed silica surface and water at pH 7 corresponds to a contact angle of 31°. This is significantly higher than the contact angle of water on a pyrolyzed silica surface freshly immersed into liquid octane. While the surface cleanliness was measured after cleaning, it was not measured after substrate immersion in the acidic or alkaline solutions. It is possible that the comparatively low non-dispersive interaction energy observed for pyrolyzed silica is partially an artifact caused by contamination of the cleaned silica before immersion into liquid oc-tane. Figure 4 shows similar behavior fo r the glass surfaces, suggesting that the alu-minoborosilicate and sodalime glasses show behavior similar to that of a silica surface. This phenomenon may be due to the leaching of soluble alkaline oxides from the glass surfaces during chromic acid cleaning, leaving a surface enriched in silica that behaves essentially in the same way as a chromic acid cleaned silica surface. In Figure 5, the minimum in the non-dispersive interaction energy between glass and water at pH 9 is not present for pyrolyzed sodalime glass. This mini-mum was presumed to be associated with a high sodium ion concentration in solution, neutralizing the SiO" groups at the glass surface. The presence of sodium oxide (see Table 1) in the sodalime glass composition may generate a high so-dium environment for the the silano l groups at the glass surface. The high sodium concentration in the glass may thus be equivalent to a high sodium concentration in solution, neutralizing the p.z.c.
DOI link for The non-dispersive interaction energy between glass and water as a function of pH is expected to reflect the surface charge generated by the exposed chemical functions on the clean glas s surface. The variations in surface charge, generated by the exposed SiOH and aluminum oxide groups, is expected to give rise to fea-tures representing the surface chemistry of the clean glass. The scatter i n the data shown in Figures 4 and 5 allows only general trends to be discerned. The p.z.c.'s at pH 3 and 9 have been described in the preceding paragraphs. It is interesting to note that the chromic acid cleaned glass surfaces behave in a similar manner, showing virtually identical trends. The pyrolysis cleaned glass surfaces show dif-ferences in their behavior across the different glass compositions. These trends correlate with those observed for organic contamination of these surfaces, as de-scribed in Section 3.1, where the chromic acid cleaned glass surfaces all showed similar behavior, while the pyrolyzed glass showed significant differences in its sensitivity to contamination. In particular, the pyrolyzed silica surface shows far lower non-dispersive interaction energy with water than the pyrolyzed Corning code 1737 or sodalime glasses. This features correlates with the high degree of adsorbed contamination, described in Section 3.1, for the pyrolyzed silica surface. The datum in Figure 5 for the non-dispersive interaction energy between a py-rolyzed silica surface and water at pH 7 corresponds to a contact angle of 31°. This is significantly higher than the contact angle of water on a pyrolyzed silica surface freshly immersed into liquid octane. While the surface cleanliness was measured after cleaning, it was not measured after substrate immersion in the acidic or alkaline solutions. It is possible that the comparatively low non-dispersive interaction energy observed for pyrolyzed silica is partially an artifact caused by contamination of the cleaned silica before immersion into liquid oc-tane. Figure 4 shows similar behavior fo r the glass surfaces, suggesting that the alu-minoborosilicate and sodalime glasses show behavior similar to that of a silica surface. This phenomenon may be due to the leaching of soluble alkaline oxides from the glass surfaces during chromic acid cleaning, leaving a surface enriched in silica that behaves essentially in the same way as a chromic acid cleaned silica surface. In Figure 5, the minimum in the non-dispersive interaction energy between glass and water at pH 9 is not present for pyrolyzed sodalime glass. This mini-mum was presumed to be associated with a high sodium ion concentration in solution, neutralizing the SiO" groups at the glass surface. The presence of sodium oxide (see Table 1) in the sodalime glass composition may generate a high so-dium environment for the the silano l groups at the glass surface. The high sodium concentration in the glass may thus be equivalent to a high sodium concentration in solution, neutralizing the p.z.c.
The non-dispersive interaction energy between glass and water as a function of pH is expected to reflect the surface charge generated by the exposed chemical functions on the clean glas s surface. The variations in surface charge, generated by the exposed SiOH and aluminum oxide groups, is expected to give rise to fea-tures representing the surface chemistry of the clean glass. The scatter i n the data shown in Figures 4 and 5 allows only general trends to be discerned. The p.z.c.'s at pH 3 and 9 have been described in the preceding paragraphs. It is interesting to note that the chromic acid cleaned glass surfaces behave in a similar manner, showing virtually identical trends. The pyrolysis cleaned glass surfaces show dif-ferences in their behavior across the different glass compositions. These trends correlate with those observed for organic contamination of these surfaces, as de-scribed in Section 3.1, where the chromic acid cleaned glass surfaces all showed similar behavior, while the pyrolyzed glass showed significant differences in its sensitivity to contamination. In particular, the pyrolyzed silica surface shows far lower non-dispersive interaction energy with water than the pyrolyzed Corning code 1737 or sodalime glasses. This features correlates with the high degree of adsorbed contamination, described in Section 3.1, for the pyrolyzed silica surface. The datum in Figure 5 for the non-dispersive interaction energy between a py-rolyzed silica surface and water at pH 7 corresponds to a contact angle of 31°. This is significantly higher than the contact angle of water on a pyrolyzed silica surface freshly immersed into liquid octane. While the surface cleanliness was measured after cleaning, it was not measured after substrate immersion in the acidic or alkaline solutions. It is possible that the comparatively low non-dispersive interaction energy observed for pyrolyzed silica is partially an artifact caused by contamination of the cleaned silica before immersion into liquid oc-tane. Figure 4 shows similar behavior fo r the glass surfaces, suggesting that the alu-minoborosilicate and sodalime glasses show behavior similar to that of a silica surface. This phenomenon may be due to the leaching of soluble alkaline oxides from the glass surfaces during chromic acid cleaning, leaving a surface enriched in silica that behaves essentially in the same way as a chromic acid cleaned silica surface. In Figure 5, the minimum in the non-dispersive interaction energy between glass and water at pH 9 is not present for pyrolyzed sodalime glass. This mini-mum was presumed to be associated with a high sodium ion concentration in solution, neutralizing the SiO" groups at the glass surface. The presence of sodium oxide (see Table 1) in the sodalime glass composition may generate a high so-dium environment for the the silano l groups at the glass surface. The high sodium concentration in the glass may thus be equivalent to a high sodium concentration in solution, neutralizing the p.z.c.
ABSTRACT
The silica surface shows a slight increase in the oxidation of its native surface silicon oxide film following UV/ozone cleaning. The aluminoborosilicate shows little change in its surface composition between the chromic acid or pyrolysis cleaning. The sodalime glass shows a loss of sodium following chromic acid cleaning. This reflects a leaching of the sodium oxide from the glass surface layer by exposure to acid. The residual sodium atoms may lie at a sufficient depth in the glass so as not to be removed by contact with the chromic acid. This measurement of glass surface composition indicates leaching of soluble alkaline oxides from the glass surface. However, the changes in the atomic composition of the glass surfaces appear small when compared to the observed differences in glass surface behavior.
