functionalized surfaces on porous silica by atomic layer ... - Aaltodoc

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Figure 17. Stepwise deposition of a high-density aminopropylsiloxane network on silica. VI 43
APTS molecules/ nm 2 Carbon atoms/ nm 2 3.2 3.0 2.8 2.6 2.4 2.2 2.0 1.8 1.6 10.0 9.0 8.0 7.0 6.0 5.0 4.0 after APTS treatment after w ater treatment 1 2 3 4 5 Number of APTS/water cycles after APTS treatment after w ater treatment 1 2 3 4 5 Number of APTS/water cycles Figure 18. Effect of APTS/water cycles on the surface density of APTS molecules (above) and carbon atoms (below) on silica pretreated at 450 °C. VI After four aminosilane/water cycles, all silanols were reacted and the surface was saturated, and the maximum amino group density was achieved. Thus, the repetition of these cycles resulted in the formation of a high-density aminopropylsiloxane network, which is assumed to grow through horizontal polymerization of silane molecules as a result of the saturation achieved. An idealized scheme of a dense amino-terminated siloxane network is shown in Figure 19 where one nm 2 of silicon dioxide surface containing approximately five silanol groups has reacted with three aminosilane molecules. The planar surface shown in Figure 19 is a simplified scheme of the silica surface heat-treated at 450 °C. In reality, only half of the OH groups are isolated and the other half hydrogen-bonded, and all hydroxyl groups do not react. A molecular model of the aminosilylated silicon dioxide surface VI,59-60 suggests that the maximum number of amino groups is ca. 3.0 per nm 2 , as was also observed in the experimental results. Thus, a monolayer was successfully deposited on silica with the present method. 44
Page 1 and 2: Helsinki University of Technology I
Page 3 and 4: Distribution: Helsinki University o
Page 5 and 6: PREFACE The experimental work of th
Page 7 and 8: THE AUTHOR’S CONTRIBUTION TO THE
Page 9 and 10: MTES Methyltriethoxysilane MTMS Met
Page 11 and 12: 1. INTRODUCTION There is growing in
Page 13 and 14: 2. GENERAL BACKGROUND As background
Page 15 and 16: Figure 2. Gas-phase deposition of
Page 17 and 18: 3-Bromopropyltrichlorosilane Glass
Page 19 and 20: the number of cycles applied. Adjac
Page 21 and 22: announced ALD to be the method-of-c
Page 23 and 24: precursor molecules compared to the
Page 25 and 26: Figure 5. Distilled water was used
Page 27 and 28: 3.2.2 Deposition of several surface
Page 29 and 30: 4. RESULTS AND DISCUSSION The effec
Page 31 and 32: Wave number/ cm -1 Figure 8. DRIFT
Page 33 and 34: Table 3. Results from TG and 1 H MA
Page 35 and 36: Various signal-processing technique
Page 37 and 38: 450 °C, the sharp peak due to free
Page 39 and 40: only monodentately bound, but also
Page 41 and 42: mono- and bidentate bonding modes o
Page 43: The reaction of the amino groups of
Page 47 and 48: Figure 20. Deposition of pyromellit
Page 49 and 50: 5. CONCLUSIONS Because ALD growth i
Page 51 and 52: 6. REFERENCES 1. Vansant, E.F., Van
Page 53 and 54: 64. Haller, I., J. Amer. Chem. Soc.
Page 55 and 56: 135. Maciel, G.E. and Sindorf, D.W.

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