Revealing the influence of the solvent in combination with temperature, concentration and pH on the modification of TiO2 with 3PA

Aqueous or solvent based surface modification: The influence of the combination solvent – organic functional group on the surface characteristics of titanium dioxide grafted with organophosphonic acids

“…Therefore, it is very unlikely to achieve 4.2 groups/nm². Even when longer reaction times (24 h) are used, no increase in modification degree has been observed [26]. In the case of a grafting density of 3.2 groups/nm², the surface coverage does not exceed 75 % of that of a full monolayer.…”

“…Moreover, in the P-OTi region a superposition of four peaks is observed: 1110, 1082, 1045 and 1012 cm -1 . These indicate different binding types onto the surface [26]. By increasing the temperature from 90 to 120 °C the peak at 1012 cm -1 becomes more intense, while the peak at 1082 cm -1 diminishes.…”

“…The titania support material is subtracted to clearly evidence the differences in the sample after the modification [26]. Newly formed bonds gave positive peaks, while negative peaks indicated that groups had reacted.…”

“…The modification degree was calculated from these mass losses (250-450 °C for 3PA and 300-500 °C for PhPA). This method was previously validated by comparing the modification degree calculated from the mass loss in TGA to the modification degree calculated from the detected amount of phosphorus by SEM EDX [26]. It is known that the hydrocarbon part of the PA will undergo a thermo-oxidation while the phosphorus atom remains bonded to the surface [20].…”

“…In our previous study, the impact of synthesis conditions on solute-surface interaction was investigated by altering the propylphosphonic acid (3PA) concentration, pH and reaction temperature in water and toluene [26].…”