원자간력 현미경을 사용한 Water-methyl alcohol System의 마이카에서의 NaCl의 결정성장에 관한 연구

손세영, 한성웅, 김종민, 김우식,Hiroshi Muramatsu, 장상목

동아대학교 공과대학 화학공학과*

일본 세이코연구소, R&C Center**

Theories and Applications of Chem. Eng., 2002, Vol. 8, No. 1

화학공학의 이론과 응용 제8권 제1호 2002년

경희대학교 공과대학 화학공학과***

Crystal growth rate of Sodium Chloride on Mica in the Water-methyl alcohol System used by Atomic Force Microscopy.

Se-Young Son*, Sung-Woong Han*, Jong-Min Kim**, Woo-Sik Kim***,

Hiroshi Muramatsu** and Sang-Mok Chang*

Dept. of Chemical Engineering, College of Engineering, Dong-A University*

R&D Center, Seiko Instruments Inc., Chiba, Japan**

Dept. of Chemical Engineering, Kyoung-Hee University, Seoul, Korea***

ABSTRACT

The face specific crystal growth rates of sodium chloride (NaCl) in aqueous solution have been determined under the influence of the concentration of methyl alcohol. Mica has been used in the controlled crystallization of NaCl. The difference in the crystallization efficiency for the different surfaces of bare mica, Mg2+ soaked mica is discussed.

The best of crystallization is found from the surface of bare mica for the same experimental condition. Increasing the concentration of methyl alcohol, the particle size and amount of NaCl was increased. From AFM images, it can be confirmed the difference of crystallization of NaCl.

keywords: Crystallization, Mica, NaCl, AFM.

INTRODUCTION

Since it has been found that the presence of additives or contaminants can influence the crystal habit significantly, the search for face specific growth inhibitors has become an interesting field for industrial crystal habit is not wanted, the more isometric growth forms are preferred. Therefore attempts are made to discover face specific additives which increase the crystal growth rate of the fastest growing directions[1].

Recently, a range of strategies has been explored to control nucleation and growth of crystals based on molecular recongnition at interfaces. These methods include template-directed crystallization under compressed Langmuir monolayers, on self-assembled monolayers (SAMs) [2,3], on oriented polymer films[4], and in surfactant aggregates.

In this study we have been used the mica to confirm the difference in the crystallization efficiency for the different surfaces of bare mica, Mg2+ soaked mica is discussed.

The relation with the concentration of methyl alcohol and the particle size and amount of crystallization was also discussed with AFM images.

EXPERIMENTAL

Slide glass was obtained from Matsunami Glass Ltd. (thickness: 0.12-0.17 mm, width 2450 mm), washed with acetone and DDW. Mica of thickness 0.01 mm was purchased from HKK Inc., washed with acetone and deposited slide glass with an adhesive bond. In the cases of experiments with divalent cation-treated mica, the treatments were also performed before crystallization. Divalent cation-treated mica was prepared by dropping a 10 L portion of 1 mM MgCl2 aqueous solution and waiting for 10 min.

The mica soaked in 1M NaCl solution with 10%, 20%, 40% methyl alcohol respectively for 10 minutes.

After making NaCl crystal on the mica, washed with ethyl alcohol and blew with N2 gases.

RESULTS AND DISCUSSION

Fig. 2. The NaCl crystals on bare mica in 1M NaCl solution with 10% methyl alcohol for 10 minutes.

Fig. 1. The NaCl crystals on Mg 2+ soaked mica in 1M NaCl solution with 10% methyl alcohol for 10 minutes.

Figure 1 shows the NaCl crystals on the mica dropped a 10 L portion of 1mM MgCl2 solution in 1M NaCl solution with 10% methyl alcohol for 10 minutes. It can be confirmed that the NaCl crystals grew irregularly.

Figure 2 shows the NaCl crystals on the surface of bare mica in same conditions with figure 1. On Mg2+ soaked mica, NaCl particles grew on the local areas. But the crystals grew more regularly on the surface of bare mica than Ｑg2+ soaked mica.

Fig. 3. The NaCl crystals on bare mica in 1M NaCl solution with 40% methyl alcohol for 10 minutes.

Fig. 4. The NaCl crystals in 1M NaCl solution with 20% MeOH for 10 minutes on Aminosilane treated mica.

In case of Mg2+ soaked mica, there is no heterogeneous crystallization except for homogeneous crystallization. So the crystals grew locally and irregularly. But the case of bare mica, negative charge of the surface on bare mica has interaction with Na+ ion in the NaCl solution.

Figure 3 shows the NaCl crystals on bare mica in 1M NaCl solution with 40% methyl alcohol for 10 minutes.

It can be shown in this figure increasing the concentration of methyl alcohol, the particle size and amount of NaCl was increased remarkably.

Each of Figure 4 & Figure 5 is shown the result of NaCl crystallization on mica which treated the differrent silane compound.

Fig. 5. The NaCl crystals in 1M NaCl solution with 20% MeOH for 10 minutes on Ethylsilane treated mica.

In this case, We observed that this result didn't have differences for the crystal of NaCl 3-aminopropyl-triethoxysilane coated mica and Ethyltriethoxysilane coated mica.

CONCLUSIONS

Two kinds surface of mica have been investigated about their effect upon the crystallization of sodium chloride. The positively charged mica can not profoundly influence the crystallization. While the negative charged mica has interaction with NaCl crystals in solution.

Increasing the concentration of methyl alcohol, the particle size and amount of NaCl was increased.

REFERENCES

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organic films on silicon substrates" Langmuir, 12, 538, 1996.

[3]J. Aizenberg, A.J. Black, G.M. Whitesides, □"Patterning disorder in monolayer resists for the fabrication of sub-100-nm structures in silver, gold, silicon, and aluminum"□, J. Am. Chem. Soc., 121, 4500, 1999.

[4] A. Berman, D.J. Ahn, A. Lio, M. Salmeron, A. Reichert, D. Charych, □"Total alignment of calcite at acidic polydiacetylene films-cooperativity at the organic-inorganic interface"□,Science, 269, 515, 1995.