Surface Reactivity Control of a Borosilicate Glass Using Thermal Poling

The ability to control glass surface reactivity at different length enables key properties required for future “smart substrates”. Employing a thermal poling process on a specific borosilicate glass composition can yield a surface with tailored physical and chemical properties. This work shows that during poling, alkali contained in the glass matrix migrates from the anode to the cathode side of the specimen, yielding the formation of an alkali-depleted layer under the anode. We have shown that this process is responsible for structural changes in the glass network and the formation of a frozen electric field within the glass. Network reorganization is linked to the creation of BØ 3 units, which replace BØ 4 – entities upon migration of the alkali ions. The resulting newly charged borate structure leads to a measurable change in the glass’ affinity to atmospheric water, being attracted to the poled anodic zone. Such spatial control of surface hydrophilicity can aid in the creation of tailored surface functionality.