Supporting Information

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1 Supporting Information Supercritical Hydrothermal Synthesis of Carboxylic Acid-surface-functionalized TiO 2 Nanocrystals: ph Sensitive Dispersion and Hybridization with Organic Compounds Toshihiko Arita,* 1 Ken-ichi Moriya, 2 Kimitaka Minami, 3 Takashi Naka, 4 and Tadafumi Adschiri* 3 1 Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba-ku, Sendai, Miyagi Department of Chemistry, Graduate School of Science, Tohoku University, 6-3 Aramakiaoba, Aoba-ku, Sendai, Miyagi WPI Research Center: Advanced Institute for Materials Research, Tohoku University, Katahira, Aoba-ku, Sendai, Miyagi National Institute for Materials Science, Sengen, Tsukuba, Ibaraki (Received June 23, 2010; CL ; tarita@tagen.tohoku.ac.jp, ajiri@tagen.tohoku.ac.jp) Copyright The Chemical Society of Japan

2 1. Experimantal details: Materials Titanium powder (99%, Aldrich), 28 % NH 4 OHaq (WAKO), 30 % H 2 O 2 aq (WAKO), glyceric acid (97%, WAKO), diethyl decylphosphonate (DDP, 98%, lancaster), ethyl 11-bromoundecanate (99%, Aldrich), triethyl phosphite (99%, Aldrich), N-ethyl N'-3-dimethylaminopropylcarbodiimide hydrochloride (EDAC, 99%, Aldrich), N,N-Dimethylamino pyridine (DMAP, 99%, Aldrich), concentrated H 2 SO 4 aq (WAKO), methyl methacrylate (99%, Aldrich, MMA), 2-hydroxyethyl methacrylate (99%, Aldrich, HEMA), acetic acid (99%, Aldrich), KOH (99%, WAKO), ethyl acetate (99%, WAKO), methanol (99%, WAKO), n-hexane (99%, WAKO), dimethyl formamide (DMF, 99%, WAKO), CH 2 Cl 2 (99%, WAKO) methanol (dehydrated grade, WAKO) and toluene (99%, WAKO) were purchased and used as receieved. CDCl 3 for NMR was purchased from Aldrich and used as received. Purified water was purchased from Daiwa Yakuhin was used after filtration. TiO 2 nanoparticles (NPs) without modification (Anatase 80 %, APS = 36 nm) was purchased from C.I Kasei. Co., Ltd., (NanoTek ) and used as received. TiO 2 (anatase) powder was purchased from WAKO and used as received for powder X-ray diffraction (XRD). Synthesis of water soluble Ti complex (TiGly21) The synthesis of Ti complex was carried out along with the two step reaction. We modified the method to produce stable water soluble Ti complex proposed by Kakihana and coworkers. Ref.s 250 mg (5.21 mmol) of Ti powder, 5 ml of 30 % NH 4 OHaq and 20 ml of 30 % H 2 O 2 aq were mixed and stirred at 0 C, then raised the temperature to room temperature and kept on stirring. After Ti powder was dissolved completely, 0.5 ml (2.6 mmol, 0.5 eq) of 5.2 M aqueous glyceric acid solution was added to the flask at 0 C and stirred for 10 min. The temperature of the solution was raised until 50 C in order to evacuate the water slowly. The obtained yellow solid was dissolved again into water. This solution was stored and used as a Ti precursor solution. Refs: 1) M. Kakihana et al., Inorg. Chem. 40, 891 (2001)., 2) M. Kakihana et al., Inorg. Chem. 43, 4546 (2004). Supercritical hydrothermal synthesis of ethyl 11-(diethylphosphono)undacanate (EDPU)-modified TiO 2 NCs Typical condition of the synthesis was following. 2.0 ml of 0.025M aqueous Ti complex solution and mg of ethyl 11-(diethylphosphono) undacanate (EDPU, concentration was set to c EDPU = 0.1M, after the reaction system reached sc-water condition) were introduced into an autoclave made from Hastelloy C alloy (i.v.= 5.0 ml). Then the reactor was sealed and stored in the electric furnace which was maintained at 400 C for 5 min. The pressure of the reaction system was 31 MPa which was calculated according to the PVT relation of the pure water. Ref. After the reaction, the reactor was removed from the furnace and immersed in to a water bath to terminate the reaction. The reaction products were collected by methanol and washed by centrifuge 3 times. Washed powder was dispersed in water and freeze dried. Ref: 3) W. Wagner, and A. Kruse, in Properties of Water and Steam, Springer-Verlag: Berlin, Supporting info. 1

3 Characterization of TiO 2 NCs. The average size, size distribution and shape of TiO 2 NCs were measured by transmission electron microscopy (TEM, JEM-1200 EXII (JEOL, Ltd.)). The THF solution of NCs was dropped on a standard carbon coated copper grid and dried. Electron micrographs were taken by a micrometer at an accelerating voltage of 100kV. The particle sizes were calculated from the average of more than 600 particles. The crystallographic identity of the solid products was evaluated by XRD (RINT-2000 (Rigaku)) measurement comparing with the standard database, Joint Committee for Powder Diffraction Studies (JCPDS) file for TiO 2 (No ). Fourier transfer infrared spectroscopy (FTIR) was employed to analyze how the surface modifiers bound to the surface of NCs. A KBr disc deposited NCs was settled in the FTIR spectrometer (Jasco FT/IR 680 plus) and measured spectrum at a resolution of 4 cm -1. The amount of grafted surface modifier was measured from the weight loss of the thermo gravimetry (TG). The temperature dependent weight loss of NCs was recorded under Air atmosphere (flow rate = 30 ml/min) with temperature sweep at 10 C/min by Rigaku TG8120 system. The dispersity of NPs in solvents was also measured through our eyes (taking photographs by Canon digital camera Powershot G2). Measuring the zeta potential of NCs with titration Zeta potential was measured from ph 12 by Malvern, Zetasizer Nano ZS. Because of the quite small solubility of the TiO 2 -PUA in water at lower ph area (< ph 4), the zeta potential was only measured from ph 12. In this study, 5 mg of the TiO 2 -PUA was dissolved in 10 ml of 0.01M aqueous KOH and measured zeta potential with titration. Esterification (capping) of carboxylic acids on the surface of TiO 2 -PUA with methanol The esterification of carboxylic acids on the surface of TiO 2 -PUA was carried out according to following method. 5 mg of freeze dried TiO 2 -PUA, 1 g of N-ethyl N'-3-dimethylaminopropyl carbodiimide hydrochloride (EDAC) and 100 mg of N, N-dimethylaminopyridine (DMAP) were loaded in a dried flask and the flask was vacuumed for 30 min. 10 ml of dry DMF was added in the flask and the solution was stirred at 0 C for 10min. Then, 100 μl of methanol was added and the mixture was stirred for 10 min at 0 C. The reaction was carried out at room temperature for 24 hours. After the reaction, the products were dissolved and collected by methanol. The crude powder was washed by centrifuge 3 times by CH 2 Cl 2. Obtained NCs were dispersed in cyclohexane and freeze dried. The yield of TiO 2 -PU-Me was difficult to measure accurately because exact number of carboxylic acid converted to methyl ester was very difficult to be measured, however, the yield could be estimated from the FTIR spectra by comparing the area of the C=OOH peak (because the drying of the TiO 2 -PU-Me was not perfect, C=OOH peak maybe appear at 1650 cm -1 ) with C=OOMe (1740 cm -1 ) peak. Then it would be more than 70 %. The esterification was also successfully catalyzed by sulfuric acid. Supporting info. 2

4 Grafting PMMA-b-PHEMA to TiO 2 -PUA 5-10 mg of TiO 2 -PUA, 1g of EDAC, 100 mg of DMAP and 10 ml of dry DMF were stirred 10 min at 0 C in Ar atmosphere, then 100 mg of the synthesized PMMA-b-PHEMA (MW: 30000) was added and stirred another 10 min. then the reaction was carried out at room temperature for 48 h. After the reaction 1 ml of methanol was added and stirred for 1 h to dissolve the precipitate. The PMMA-b-PHEMA grafted TiO 2 -PUA was washed 3 times by reprecipitation by CH 2 Cl 2. The esterification was also successfully catalyzed by sulfuric acid. Synthesis of ethyl 11-(diethylphosphono)undacanate (EDPU) EDPU used in this study was synthesized through the Michaelis-Arbuzou reaction. 10 g (34.1 mmol) of ethyl 11-bromoundecanate and 14.2 g (85.3 mmol) of triethyl phosphite were introduced into a 100 ml flask, then refluxed at 150 C for 16 hours. The reaction solution was vacuum dried and purified through the silica column chromatography (solvent was n-hexane : ethyl acetate = 2 : 1). The yield was 90 %. The purity was calculated from 1 H-NMR (JEOL, JNM- ECX400) spectrum (400 MHz, CDCl 3 ) δ 1.25 (t, J = 7.08, 3H), 1.32 (t, J = 7.08, 6H), (m, 12H), (m, 6H), 2.28 (t, J = 7.56, 2H), 4.12 (q, J = 7.08, 2H), (m, 4H). Hydrolysis of diethyl decylphosphonate (DDP) and ethyl 11-(diethylphosphono)undacanate (EDPU). 150 μl of DDP or EDPU and 2.0ml of deionized water were loaded into 5.0 ml volume of reactor made from Hastelloy C alloy, then sealed. The reactor was stored in the electric furnace which was kept at 400 C for 2 min. The product was collected by methanol and then the solvent evacuated. Obtained white powder was measured 1 H-NMR and calculated the yield. In both cases, the yields were higher than 98%. 2. Hydrolysis of EDPU in sc-water. 1 H-NMR was measured to check the hydrolysis of both the ethyl phosphonate and ethyl carboxylate of EDPU were occurred or not. The NMR chart of the products after 3 min reaction of EDPU at 400 C, 30MPa are shown in Fig. S1. The assignment of the peaks was below. 1 H-NMR (400 MHz, CDCl 3 ) δ (m, 12H, -CH 2 -), (m, 6H, P(O)-CH 2 -, P(O)CH 2 -CH 2 -, COCH 2 -CH 2 -), 2.27 (t, J = 7.32, 2H COCH 2 -). The yields of the hydrolysis were almost 100 %. Supporting info. 3

5 Fig. S1. NMR chart of sc-water hydrolyzed EDPU. 3. Diethyl decylphosphonate (DDP) modified TiO 2 NCs (TiO 2 -DP). Representative of the TiO 2 NCs which have the other surface modifier than EDPU, DDP modified TiO 2 NCs were shown in this section. The Image of the dispersion, TEM, FTIR, TG and XRD patterns of TiO 2 -DP synthesized in this study are shown in Fig. S2. Supporting info. 4

6 Fig. S2. Characterizations of TiO 2 -DP. Hydrophobicity, TEM, FTIR, TG and XRD. 4. The calculation of the surface coverage of the modifier. Here, we show the calculation detail of the surface coverage of the TiO 2 -PUA and TiO 2 -DP NCs. Fig. S3. Calculation detail of the surface coverage of TiO 2 -PUA and TiO 2 -DP synthesized in this study. Supporting info. 5

7 5. n-octylsuccinic anhydrous modified TiO 2 NPs (TiO 2 -DSA). Fig. S4 depicts the TEM image, FTIR and XRD pattern of the TiO 2 -DSA. There was no peak corresponding to free carboxylic acids around 1700 cm -1 in FTIR spectrum. It is suggested that the n-octylsuccinic acid is in the full ionized form and chemisorbed on the TiO 2 surface. n-octylsuccinic anhydrous Fig. S4. TEM, FTIR and XRD results of the TiO 2 -DSA. 6. FTIR spectra of methanol capped TiO 2 -PUA (TiO 2 -PU-Me) and PHEMA-b-PMMA grafted TiO 2 -PU (TiO 2 -PHEMA-b-PMMA). KOHaq neutralized TiO 2 -PUA (TiO 2 -PUA-Neutral) was prepared just mixing equal portions of 1 M KOHaq and 5 mg/5 ml of aqueous TiO 2 -PUA solution. The neutralized NCs were collected by centrifugation and dried. FTIR spectra indicate the modifier was not desorbed form the surface. Fig. S5. FTIR spectra of the TiO 2 -PU-Me, TiO 2 -PUA-Neutral and TiO 2 -PHEMA-b-PMMA. Supporting info. 6