(420f) Synthesis of Nano-Anatase to Produce Small ETS-10 Crystals for Enhanced Textile Properties

Textile production, properties
and its end-use have changed beyond recognition over the last decade.¹
Hence, functionalized textiles present a growing niche in the global textile
market² which was estimated in 2005 to be worth $400 billion.³
Coating textiles with nano sized photocatalytic material, titanosilicate
ETS-10, would impart useful functionalities, e.g., stain-resistant, odor
repellant, bactericidal⁴ and enhanced UV protection⁵ on the
composite material.

Typically, small ETS-10 crystals
are in the range of ~ 500
- 800 nm, and are synthesized using solid titania (e.g., anatase or P25 a
mixture of anatase and rutile) sources.^6,7
However, smaller ETS-10 crystallites are required to generate a smooth uniform
surface coating with a highly effective surface area. The rate of dissolution
of the anatase is considered to be the rate determining step in ETS-10
crystallization.⁷ Thus, it is hypothesized that by incorporating
nano-anatase in ETS-10 synthesis, multiple ETS-10 nucleation points can be
generated and anatase dissolution rate would be increased, resulting in the
growth of uniform, highly crystalline ETS-10 products with fine particle size
less than 500 nm.

Colloidal TiO₂
suspensions with the average hydrodynamic particle diameter of ~ 12 nm has been
successfully prepared from titanium isopropoxide.^8,9,10
X-ray powder diffraction analysis of anatase powder obtained by drying these
colloidal suspensions in air at low temperatures showed phase-pure anatase with
the average crystallite size in the 4 - 5 nm range. Scanning electron
microscopy and particle size distribution analysis both confirmed the presence
of nano-sized particles in all prepared TiO₂ sols. Preliminary
investigations have shown that the size of anatase particles influenced the pH
of ETS-10 synthesis mixture, thereby giving rise to impurities such as ETS-4.
An optimum pH of ~10.6 has been shown to favor ETS-10 formation.⁷ Based
on these facts reaction mixture compositions that would yield highly
crystalline ETS-10 materials with fine particle size were investigated.

1          T.
L. Vigo; Textile Processing and
Properties 11, U.S. Dept of Agriculture, 1994

2          W.
Chang, P. Kilduff; Small Business &
Technology Development Center, May 2002

3.         B. Mahltig, H. Haufe, H. Bottcher; J.
of Mater. Chem. 2005, 15,
4385–4398 

4.         K.
Qi, W.A. Daoud, J.H. Xin, C.L. Mak, W. Tang, W.P Cheung; J. Mater. Chem. 2006,
16, 4567 - 4574.

5          W.A.
Daoud, S.K. Leung, W.S. Tung, J.H. Xin, K. Cheuk, K. Qi; Chem. Mater. 2008, 20,
1242-   1244

6          L.
Lv, Fabing Su, X.S. Zhao; Micropor.
Mesopor. Mater. 76, 2004,
113-122

7          J.
Rocha, A. Ferreira, Z. Lin, M.W. Anderson;  Micropor. Mesopor. Mater. 23, 1998,
253-263

8          K.
Qi, X. Chen, Y. Liu, J.H. Xin, C.L. Mak, W.A Daoud; J. Mater. Chemi.
17, 2007, 3504

9          W.A
Daoud, J.H. Xin; Chem.Commun.
16, 2005, 2110

10        K.Qi, W.A Daoud, J.H. Xin, C.L.
Mak, W. Tang, W.P. Cheung; J.  Mater. Chem. 16, 2006, 4567- 4574