Printer Friendly

Preparation of transparent ultrahydrophobic silica film by sol--gel process.

[C] ACA and OCCA 2010

Abstract Transparent ultrahydrophobic films were synthesized by sol--gel process with organic silicones modified into silica sol and cured under UV irradiation. The effects of hydrolysis temperature, hydrolysis time, molar ratio of organic silicone to silica sol, and surface morphology on the hydrophobicity of the films were discussed in detail using FTIR spectroscopy, scanning electron microscopy (SEM), AFM, optical transmission, and contact angle measurement, respectively. The AFM and SEM images indicated that the surface roughness enhanced the hydrophobicity of the films. The results revealed that methyl-trimethoxysilane (MTMS)-modified silica film prepared at 50[degrees]C for 2 h with an MTMS/silica sol molar ratio of 1:10 had a very high contact angle (130[degrees]). However, the higher hydrolysis temperature and longer reaction time might have accelerated the self-condensation of silanol and decreased the contact angle of the films.

Keywords Ultrahydrophobic film, Transparency, Silica sol, Organic silicone, Sol--gel process, Contact angle

Introduction

Amazed by self-cleaning lotus leaves, (1) ultrahydrophobic surfaces with a water contact angle (CA) higher than 120[degrees] have attracted the great interest of researchers and scientists over the last few years. The films have been used widely in the automotive glass (2) and high building glass (3) industries. In general, there were two basic approaches to increasing the hydrophobicity of the films. One was to change the surface chemical structure, which decreased the surface energy of the films. (4), (5) The other was to increase the surface roughness so as to enhance the effective surface area. (6-8) For the formation of the films, modification of the surface chemical structure was always combined with the enhancement of surface roughness.

Various methods have been proposed to fabricate ultrahydrophobic film, such as the sol--gel method, (9-11) the solution method, (12-14) the etching method, (15-17) mechanical treatment, (18-20) aligning carbon nano-tubes, (21), (22) electrospinning, (23), (24) and others. (25-29) However, some methods for preparing the film require complicated equipment. Moreover, the film is not always optically transparent, which is due to the scattering by particles or pores that were introduced to make desired surface roughness.

In our work, the transparent ultrahydrophobic film was prepared by the sol--gel process in two steps that have not been reported before. First, we prepared the inorganic/organic hybrid sol through a reaction between silica sol and organic silicones, and then the hybrid sol further reacted with hydroxyl propyl acrylate (HPA). Second, the film was prepared by putting the hybrid sol under UV irradiation curing, which was considered a fast and effective way to obtain the films. (30) To prepare the film, the relationships between CA, surface roughness, and organic silicones were explored. The factors in affecting the surface energy and roughness were discussed.

Experiment

Materials

Silica sol was supplied by Xiaguang Reagent Co., Jiangsu, China. Methanol and n-propanol were supplied by Guoyao Reagent Co., Shanghai, China. Methyl-trimethoxysilane (MTMS), Ethyl-triethoxysilane (ETES), [gamma]-Methacryloxypropyl trimethoxy silane (MPMS), and Hexamethyl disilizane (HMDS) were supplied by Yehao Chemistry Co., Shanghai, China. HPA and 1,6-Hexancdiol diacrylate (HDDA) were supplied by Baorun Chemistry Co., Shanghai, China. 2-Hydroxy-2-methylpropiophenone (HMPP) was supplied by Qiba Chemistry Co., Shanghai, China.

Synthesis of inorganic/organic hybrid sol

Four kinds of inorganic/organic hybrid sols were prepared and referred to as MTMS hybrid sol, ETES hybrid sol, MPMS hybrid sol, and HMDS hybrid sol, respectively. The pH value of the hydrolysis process was controlled at 3 (using HCl as a catalyst). In the case of MTMS, it was hydrolyzed in a solution with a silica sol/MTMS/[H.sub.2]O/methanol molar ratio of 10:1:16:8. The hydrolysis temperature and hydrolysis time were well-controlled to make sure MTMS was hydrolyzed, and then the hydrolyzed MTMS was grafted onto silica sol by hydroxyl contraction. The resulting MTMS hybrid sol was end-capped by adding HPA with a silica sol/HPA molar ratio of 4:1 at 50[degrees] for 2 h, and then dried at room temperature for 5 h in a vacuum oven. The other three types of hybrid sols were prepared using the same method.

Preparation of ultrahydrophobic films

The aforementioned hybrid sol end-capped with HPA was mixed with HMPP, HDDA, and n-propanol (the weight ratio of the hybrid sol/HMPP/HDDA/n-propanol of 100:1:4:100), and then was coated on automotive glass and cured under a UV curing lamp for 3 min at room temperature. The power of the UV curing lamp was 1 kW, and the UV wavelength was 365 nm. Moreover, the distance between the sample and the UV curing lamp was 7 cm.

[ILLUSTRATION OMITTED]

Characterization

The contact angle of each film was measured by the SL200B contact angle meter (Solon Technology Co., China) at room temperature, and the measurement accuracy was up to [+ or -]1[degrees]. The contact angles were measured at 10 different spots for each film, and the average value was adopted as the contact angle. The atomic force microscopy (NSK Co., Japan) and scanning electron microscopy (FEI Co., America) were introduced to observe the surface morphology of the films. The hybrid sol before UV irradiation curing was dried to a constant weight in a vacuum oven at 40[degrees]C for 10 h. The IR spectra were carried out by EQUINOXSS FTIR spectrometer (Bruker Co., Germany). The optical transmission spectra were measured by PE100 spectroscopy (Perkin Elmer Co., America).

Results and discussion

Reaction mechanism

During the sol--gel process, the organic silicone was hydrolyzed and grafted onto silica sol. (31-33) In the case of MTMS, the hydrolyzable Si-[OCH.sub.3] groups of MTMS were expected to hydrolyze one by one, and then the resulting silanol would be grafted on silica sol. Thus, the hydrophobic Si-[CH.sub.3] groups would be introduced into silica sol through Si-O-Si bonds, described as Step (1) and Step (2) in Scheme 1. However, the self-condensation of silanol might happen during the sol--gel process, described as Step (3) in Scheme 1. The self-condensation reaction could decrease the amount of reacted Si-OH groups and lead to fewer hydrophobic Si-[CH.sub.3] groups introduced into silica sol, which would obviously damage the hydrophobicity of the films. (31) To achieve the ultrahydrophobic films, the self-condensation of silanol should be avoided as much as possible.

The prepared hybrid sol was cured and formed the film under UV irradiation. In the case of MTMS-modified hybrid sol, the FTIR spectra of the hybrid sol (Fig. 1a) and the curing film (Fig. 1b) were shown in Fig. 1 to verify the UV irradiation curing of the hybrid sol. The broad peak at around 3430 [cm.sup.-1] was attributed to the O-H bond of the Si-OH group. The peaks at 2957 [cm.sup.-1] and 2835 [cm.sup.-1] corresponded to C-H stretching absorption. The peaks observed at 1712 [cm.sup.-1] and 1628 [cm.sup.-1] were due to the stretching absorption of the C=O bond and C=C bond in HAP, respectively. The peak at 1079 [cm.sup.-1] corresponded to the Si-O-Si asymmetric stretching vibration, and the peak at 803 [cm.sup.-1] was due to the Si-C bond. After UV irradiation curing, the intensity of the peaks at 3430 [cm.sup.-1] and 1628 [cm.sup.-1] decreased remarkably, and the intensity of the peak at 1079 [cm.sup.-1] clearly increased. The results indicated that the polymerization reaction of HAP and condensation reaction of Si-OH groups occurred under UV irradiation, which could lead to UV irradiation curing of the hybrid sol.

[FIGURE 1 OMITTED]

Influence of hydrolysis temperature

The hydrolysis temperature of organic silicone varied from 20[degrees] to 90[degrees] by keeping the hydrolysis time at 2 h, and the CAs of the films were shown in Fig. 2. It was observed that the CAs of the films modified by MTMS, ETES, and MPMS increased with the increase of hydrolysis temperature from 20[degrees] to 50[degrees], and then decreased with further increases in temperature. The reaction between organic silicone and silica sol was enhanced with an increase of hydrolysis temperature. The number of hydrophobic groups attached to the silica sol increased, which led to the increase in the CAs of the films. However, the self-condensation of the silanol produced by organic silicones was largely accelerated at higher temperatures (34) and resulted in a decrease in the CAs of the films. In the case of ETES, the FTIR spectra of ETES hydrolyzed at 50[degrees] and 90[degrees] are shown in Fig. 3. The peak at 1080 [cm.sup.-1] corresponded to the Si-O-Si asymmetric stretching vibration. The broad Si-O-Si peak of hydrolytic ETES at 90[degrees] indicated that the self-condensation of the silanol reacted strongly and formed a network structure inside silica sol, (35) which could lead to lower hydrophobicity of the films.

[FIGURE 2 OMITTED]

In addition, it was shown that the CA of the film modified by HMDS increased slowly with the increase in hydrolysis temperature from 20[degrees] to 80[degrees]. The more branched structure Si-([CH.sub.3][).sub.3] and less reactive Si-OH group might contribute to the decrease in the reaction rate of HMDS due to the steric hindrance. (31) This led to the optimal hydrolysis temperature of HMDS being much higher than those of other organic silicones.

Influence of hydrolysis time

The hydrolysis time of organic silicone was varied from 0.5 to 8 h by keeping the hydrolysis temperature at 50[degrees], and the CAs of the films are shown in Fig. 4. It was observed that the CAs of three kinds of films modified by MTMS, ETES, and MPMS increased with the increase of the hydrolysis time up to 2 h, and then decreased slightly thereafter. With the increase in hydrolysis time, the number of hydrophobic groups grafted on the silica sol increased. It led to an increase in the CAs of the films. However, with further increases in hydrolysis time over 2 h, the CAs of the films decreased slightly due to the self-condensation of silanols produced by organic silicones. Moreover, the CA of HMDS-modified films increased with an increase in hydrolysis time from 0.5 to 8 h. It indicated that the steric hindrance of HMDS decreased the reaction rate (31) and led to much longer times needed to complete the graft reaction.

With the increase in hydrolysis time, the self-condensation of silanol was obviously enhanced, and the FTIR spectra of MTMS hydrolyzed for 1 h and 8 h are shown in Fig. 5. It was observed that the peak of the Si-O-Si bond at 1070 [cm.sup.-1] hydrolyzed for 8 h was much larger and broader than the one hydrolyzed for 1 h. The Si-O-Si bonds formed a network in the hybrid sol and enhanced the hardness of the films, but they also increased the viscosity of the hybrid sol and led to the formation of large [SiO.sub.2] particles on the surface of the films, as shown in Fig. 6. The film hydrolyzed for 8 h (Fig. 6b) had many more [SiO.sub.2] particles on the surface compared with the one hydrolyzed for 1 h (Fig. 6a). The particles led to excess surface roughness of the film, which resulted in a decrease of the optical transparency.

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

Influence of the molar ratio of organic silicone to silica sol

The molar ratio of organic silicone to silica sol (r value) was varied from 0.025 to 0.4 by keeping the hydrolysis temperature at 50[degrees] and the hydrolysis time for 2 h, and the curves and data are shown in Fig. 7 and Table 1.
Table 1: Influence of effective volume of hydrophobic groups on the
optimal r values

Organic         MTMS        ETES                MPMS
silicones

Hydrophobic     [CH.sub.3]  [C.sub.2][H.sub.5]  C=C([CH.sub.3])COO
group                                           ([CH.sub.2][).sub.3]

Effective             0.04                0.09                  0.29
volume

Optimal r              0.1                0.15                  0.20
value

CA of the              130                 110                    74
film/[degrees]

Organic         HMDS
silicones

Hydrophobic     3([CH.sub.3])
group

Effective                0.35
volume

Optimal r                0.25
value

CA of the                 109
film/[degrees]


[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

[FIGURE 7 OMITTED]

It was observed that the CA of each film increased with an increase of the r value up to an optimal value and then remained constant thereafter, and the optimal [gamma] value of organic silicone increased with an increase in the effective volume (the ratio of the size of hydrophobic group to the number of reactive Si-OH groups) of the hydrophobic group. (36-38) In the case of MTMS, with increase of MTMS [gamma] value from 0.025 to 0.1, the number of hydrophobic Si-[CH.sub.3] groups grafted on silica sol increased and led to the increase in CA of the film from 90[degrees] to 130[degrees]. The CA of the film remained constant due to almost completion of the surface graft reaction of the Si-OH group while the [gamma] value varied from 0.1 to 0.4. In the case of HMDS, its effective volume was increased from 0.04 of MTMS to 0.35. Thus,

the stronger steric hindrance and less reactive Si-OH group might have contributed to the decrease in the reaction rate of the HMDS. With an increase of HMDS [gamma] value from 0.025 to 0.25, the CA of the film increased slowly from 55[degrees] to 109[degrees]. The optimal [gamma] value of HMDS was 0.25. which was much higher than the 0.1 of MTMS.

Influence of surface morphology

In general, the hydrophobicily of the film enhanced with an increase in surface roughness, but the surface roughness should be less than 100 nm for transparent film. (25)

The AFM and SEM images of the films are shown in Figs. 8 and 9 and the AFM images were recorded at 2 [micro]m x 2 [micro]m planar in contact mode. It was observed that the surface roughness of the films was less than 5 nm. The AFM image of the film modified by MPMS showed no bright-bark contrast compared with images of other films. It indicated that the MPMS-modified was smoother than other films, which led to the decrease of the hydrophobicity of the film.

In addition, due to the strong hydrogen bond interaction between the C=C([CH.sub.3])COO([CH.sub.2][).sub.3] group of MPMS and the Si-OH group of silica sol, the hybridization process of MPMS and silica sol could be promoted. (39) Therefore, it was easy to obtain the smooth surface (as shown in Fig. 9b), and the CA of the film was decreased. On the contrary, the hydrogen bond interaction between the [CH.sub.3] or [CH.sub.2] [CH.sub.3] groups and the Si-OH group of silica sol was very weak, and the molecular interaction between them could be ignored. Thus, the surface roughness was consequently enhanced, as shown in Fig. 9a. There were lots of particles with a diameter less than 100 nm on the surface of the MTMS-modified film, which could enhance the surface roughness and increase the CA of the film.

[FIGURE 8 OMITTED]

[FIGURE 9 OMITTED]

Transparency of the films

The optical transmission spectra of the films modified by organic silicones are shown in Fig. 10. Excellent optical transmission of the films modified by MTMS, ETES, and MPMS was shown in the visible light range from 380 to 780 nm, and the optical transmission of the films was higher than 80%. However, the optical transmission of the HMDS-modified film was between 35% and 75%, and the lowest optical transmission was only 35% in the visible light range.

[FIGURE 10 OMITTED]

In addition, the transparency of the film had close relation with the number and size of particles or pores on the surface of the film, as shown in Fig. 11. The surface of the MTMS-modified film had lots of particles and pores with a diameter less than 150 nm (Fig. 11a). These particles and pores could transmit by visible light and led to an excellent optical transmission of the films. In the case of the HMDS-modified film (Fig. 11b), however, it had lots of large [SiO.sub.2] particles with diameters over 1 [micro]n formed on the surface. The large [SiO.sub.2] particles prevented the transmission of visible light and resulted in the decrease of the transparency of the film.

[FIGURE 11 OMITTED]

Conclusion

Transparent ultrahydrophobic silica films modified by MTMS, ETES, MPMS, and HMDS were prepared by using the sol--gel process. The FTIR spectra showed the intensity of the Si-O-Si peak enhanced with an increase of the hydrolysis temperature and reaction time between organic silicones and silica sol. This indicated the enhancement of the self-condensation of silanol, which can damage the hydrophobicity of the film. The MTMS-modified film with CA as high as 130[degrees] was produced at 50[degrees]C for 2 h with the MTMS/silica sol molar ratio of 1:10, and the optical transmittance of the film was higher than 85% in the visible light range. With high CA and excellent transparency, the film could be used as self-cleaning windshields on automobiles.

References

(1.) Barthlott, W, Neinhuis, C, "Purity of the Sacred Lotus, or Escape from Contamination in Biological Surfaces." Planta, 202 1-8 (1997)

(2.) Shang, HM, Wang, Y, Takahashi, K, Cao, GZ, "Nanostrucured Superhydrophobic Surfaces." J. Mater. Sci., 40 3587-3591 (2005)

(3.) Pilotek, S, Schmidt, HK, "Wettability of Microstructured Hydrophobic Sol-Gel Coatings." J. Sol-Gel Sci. Technol., 26 789-792 (2004)

(4.) Chen, W, Fadeev, AY, Hsieh, MC, Oner, D, Youngblood, J, "Ultrahydrophobic and Ultralyophobic Surfaces: Some Comments and Examples." Langmuir, 15 3395-3399 (1999)

(5.) Onda, T, Shibuichi, S, Satoh, N, Tsujii, K, "Super-Water-Repellent Fractal Surfaces." Langmuir, 12 2125-2127 (1996)

(6.) Yoshimitsu, Z, Nakajima, A, Watanabe, T, Hashimoto, K, "Effects of Surface Structure on the Hydrophobicity and Sliding Behavior of Water Droplets." Langmuir, 18 5818-5822 (2002)

(7.) Busscher, HJ, Van Pelt, AWJ, De Boer, P, De Jong, P, Arends, J, "The Effect of Surface Roughening of Polymers on Measured Contact Angles of Liquids." Colloids Surf., 9 319-331 (1984)

(8.) Buzio, R, Boragno, C, Biscarini, F, De Mongeot, FB, Valbusa, U, "The Contact Mechanics of Fractal Surfaces." Nat. Mater., 2 233-236 (2003)

(9.) Shirtcliffe, NJ, McHale, G, Newton, MI, Perry, CC, "Intrinsically Superhydrophobic Organosilica Sol-Gel Foams." Langmuir, 19 5626-5631 (2003)

(10.) Tadanaga, K, Morinaga, J, Matsuda, A. Minami, T, "Super-hydrophobic-Superhydrophilic Micropatterning on Flowerlike Alumina Coaling Film by the Sol-Gel Method." Chem. Mater., 12 590-592 (2000)

(11.) Nakajima, A, Abe. K, Hashimoto, K, Watanabe, T, "Preparation of Hard Super-Hydrophobic Films with Visible Light Transmission." Thin Solid Films, 376 140-143 (2000)

(12.) Ma, Y, Cao, XY, Feng, XJ, Ma, YM, Zou, H, "Fabrication of Super-Hydrophobic Film from PMMA with Intrinsic Water Contact Angle Below 90[degrees]." Polymer, 48 7455-7460 (2007)

(13.) Erbil, HY, Demirel, AL, Ave, Y, Mert, O, "Transformation of a Simple Plastic into a Superhydrophobic Surface." Science, 299 1377-1380 (2003)

(14.) Zhao, N, Xu, J, Xie, QD, "Fabrication of Biomimetic Superhydrophobic Coating with a Micro-Nano-Binary Structure." Macromol. Rapid Commun., 26 1075-1080 (2005)

(15.) Lee, SM, Lee, HS, Kim. DS, Kwon, TH, "Fabrication of Hydrophobic Films Replicated from Plant Leaves in Nature." Surf. Coat. Techno!., 201 553-559 (2006)

(16.) Cui, B, Cortot, Y, Veres, T, "Polyimide Nanostructures Fabricated by Nanoimprint Lithography and its Applications." Microelectron. Eng., 83 906-909 (2006)

(17.) Youngblood, JP, McCarthy, TJ, "Ultrahydrophobic Polymer Surfaces Prepared by Simultaneous Ablation of Polypropylene and Sputtering of Poly(Tetrafluoroethylene) Using Radio Frequency Plasma." Macromolecnles, 32 6800-6806 (1999)

(18.) Xie, QD, Xu, J, Feng, L. Jiang. L, Tang, WH, Luo, XD, Han. CC. "Facile Creation of a Bionic Super-Hydrophobic Block Copolymer Surface." Adv. Mater., 16 302-305 (2004)

(19.) Feng. L, Li, SH, Li. HJ, Zhai, J, Song, YL, Jiang, L, Zhu, DB, "Super-hydrophobic Surface of Aligned Polyacrylonitrile Nanofibers." Angew. Chem. Int. Ed., 41 1221-1223 (2002)

(20.) Yao, YH, Dong, X, Hong, S, Ge, HL, Han, CC, "Shear-controlled Micro/Nanometer-scaled Super-hydrophobic Surfaces with Tunable Sliding Angles from Single Component Isolactic Poly(propylene)." Macromol. Rapid Commun., 27 1627-1631 (2006)

(21.) Li. SH, Li, HJ, Wang, XB, Song, YL, Liu, YQ, Jiang, L, Zhu, DB. "Super-hydrophobicity of Large-area Honeycomb-like Aligned Carbon Nanotubes." J. Phys. Chem. B, 106 9274-9276 (2002)

(22.) Lau, KKS, Bico, J, Teo, KBK, Chhowalla, M, Amaratunga, GAJ, Milne, WI, Mckinely, GH, Gleason, KK, "Superhydrophobic Carbon Nanotubes Forests." Neno Lett., 3 1701-1705 (2003)

(23.) Bognitzki, M, Czdo, W, Frese, T, Schaper, A, Hellwig, M, Steinhart, M, Greiner, A, Wendorff, JH, "Nanostructured Fibers via Electrospinning." Adv. Mater., 13 70-72 (2001)

(24.) Acatay, K, Simsek, E, Ow-Yang, C, Menceloglu, YZ, "Tunable, Superhydrophobically Stable Polymeric Surfaces by Electrospinning." Angew. Chem. Int. Ed., 435210-5213 (2004)

(25.) Nakajima, A, Fujishima, A, Hashimoto, K, Watanabe, T, "Preparation of Transparent Superhydrophobic Boehmite and Silica Films by Sublimation of Aluminum Acetylacetonate." Adv. Muter., 11 1365-1368 (1999)

(26.) Jiang, L, Zhao, Y, Zhai, J, "A Lotus-leaf-like Superhydrophobic Surface: A Porous Microsphere/Nanofiber Composite Film Prepared by Electrohydrodynamics." Angew. Chem. Int. Ed., 43 4338-4341 (2004)

(27.) Tan, SX. Xie, QD, Lu, XY, Zhao, N, Zhang, XL, Xu, J, "One Step Preparation of Superhydrophobic Polymeric Surface with Polystyrene Under Ambient Atmosphere." J. Colloid Interface Sci., 322 1-5 (2008)

(28.) Woodward, I, Schofield, WCE, Roucoules, V, Badyal, JPS, "Super-hydrophobic Surface Produced by Plasma Fluorination of Polybutadiene Films." Langmuir, 19 3432-3438 (2003)

(29.) Zhao, N, Weng, LH, Zhang, XY, Xie, QD, Zhang. XL, Xu, J, "A Lotus-leaf-like Superhydrophobic Surface Prepared by Solvent-induced Crystallization." ChemPhysChem., 7 824-827 (2006)

(30.) Wouters, MEL, Wolfs, DP, Van Der Linde, MC, Hovens, JHP, Tinnemans, AHA, "Transparent UV Curable Antistatic Hybrid Coatings on Polycarbonate Prepared by the Sol-Gel Method." Prog. Org. Coat., 51 312-320 (2004)

(31.) Rao, AV, Latthe, SS, Nadargi, DY, Hiroshima, H, Ganesan, V, "Preparation of MTMS Based Transparent Superhydrophobic Silica Films by Sol-Gel Method." J. Colloid Interface Sci., 332 484-490 (2009)

(32.) Shang, HM, Wang, Y, Limmer, SJ, Chou, TP, Takahashi, K. Can, GZ, "Optically Transparent Superhydrophobic Silica-based Films." Thin Solid Films, 472 37-43 (2005)

(33.) Yang, SY, Chen, S, Tian, Y, Feng, C, Chen, L, "Facile Transformation of a Native Polystyrene (PS) Film into a Stable Superhydrophobic Surface via Sol-Gel Process." Chem. Mater., 20 1233-1235 (2008)

(34.) Salon, MCB, Bayle, PA, Abdelmouleh, M, Boufi, S, Belacem, MN, "Kinetics of Hydrolysis and Self Condensation Reactions of Silanes by NMR Spectroscopy." Colloids Surf. A. 312 83-91 (2008)

(35.) Hong, JK, Kim, HR, Park, HH, "The Effect of Sol Viscosity on the Sol-Gel Derived Low Density [SiO.sub.2] Xerogel Film for Intermetal Dielectric Application." Thin Solid Films, 332 449-454 (1998)

(36.) Bondi, A, "Van der Waals Volumes and Radii." J. Phys. Chem., 68 441-451 (1964)

(37.) Bondi, A, "Van der Waals Volumes and Radii of Metals in Covalent Compounds." J. Phys. Chem., 70 3006-3007 (1966)

(38.) Zhao, YH, Abraham, MH, Zissimos, AM, "Fast Calculation of Van der Waals Volume as a Sum of Atomic and Bond Contributions and its Application to Drug Compounds." J. Org. Chem., 68 7368-7373 (2003)

(39.) Chen, YK, Chang, KC, Wu, KY, Tsai, YL, Lu, JS, Chen, H. "Fabrication of Superhydrophobic Silica-based Surfaces with High Transmittance by Using Tetraethoxysilane Precursor and Different Polymeric Species." Appl. Surf. Sci., 255 8634-8642 (2009)

G. Wang

Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, Shanghai 200092, China

G. Wang ([??]), J. Yang ([??]), Q. Shi

School of Materials Science and Engineering, Tongji University, Shanghai 200092, China

e-mail: wanggj@tongji.edu.cn

J. Yang

e-mail: yangjiayun@gmail.com

DOI 10.1007/s11998-010-9270-5
COPYRIGHT 2011 American Coatings Association, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2011 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Author:Wang, Guojian; Yang, Jiayun; Shi, Quan
Publication:JCT Research
Geographic Code:9CHIN
Date:Jan 1, 2011
Words:3915
Previous Article:Synthesis and evaluation of tetra(2,7-octadienyl) titanate as a reactive diluent for air-drying alkyd paints.
Next Article:Preparation and characterization of UV-curable hyperbranched polyurethane acrylate.
Topics:

Terms of use | Copyright © 2017 Farlex, Inc. | Feedback | For webmasters