Preparation of aminofunctionalized TiO2 surfaces by binding of organophosphates

Abstract Titanium dioxide (TiO 2 ) powder was chemically modified with 2-aminoethyl dihydrogen phosphate (AEPH 2 ) and with 2-aminoethyl hydrogen ammonium phosphate (AEPHNH 4 ) in order to achieve an aminofunctionalized high-surface-area TiO 2 carrier suitable for more complex functionalizing. AEPH 2 was found to form the monoammonium salt AEPHNH 4 with ammonium ion rather than the diammonium salt AEP(NH 4 ) 2 . The AEPHNH 4 was thoroughly characterized by various techniques and compared with AEPH 2 . Bonding of AEPH 2 and AEPHNH 4 with TiO 2 powder was studied. According to the 31 P NMR and elemental analysis results, AEPH 2 and AEPHNH 4 form covalent chelate bidentate bonds between the phosphate group and the TiO 2 , while the amino groups remain accessible, creating uniform aminofunctionalized TiO 2 surface fully occupied by AEP groups. Amount of AEP groups on TiO 2 was limited to 1.5 wt-%.