Sol-Gel Preparation of PHFBMA/PFG/Silica Coatings with Durable Shortwave-band Antireflective Performance

doi:10.3724/SP.J.1077.2014.14039

Abstract

Abstract:

A new silica shortwave-band antireflective (AR) coating with durable optical performance on fused silica substrate was prepared by a base-catalyzed Sol-Gel process using tetraethyl orthosilicate (TEOS) as a precursor. 1H, 1H, 12H, 12H-perfluoro-dodecane-1, 12-diol (simplified as PFG) was used to control the structure and size of the silica particles in the sols, and hence decreased the refractive indices of the coatings. After Poly (2, 2, 3, 4, 4, 4-hexafluorobutyl) methacrylate (PHFBMA) being introduced into the silica sols, the AR coatings could retain a transmission about 99.9% at about 300 nm. At the same time, the transmission stability of the coatings was improved significantly, which were tested in a moisture environment and an organic-containing vacuum chamber, respectively.

Key words: antireflective coating, Sol-Gel, shortwave-band, hydrophobicity, organic contamination

CLC Number:

TQ174

ZHANG Qing-Hua, HUI Hao-Hao, YANG Wei, WEI Yao-Wei, WANG Jian, XU Qiao. Sol-Gel Preparation of PHFBMA/PFG/Silica Coatings with Durable
Shortwave-band Antireflective Performance[J]. Journal of Inorganic Materials, 2014, 29(6): 667-672.

Figures/Tables 8

Fig. 1 FTIR absorption spectra of PFG/PHFBMA/silica xerogel, pure silica xerogel, PFG and PHFBMA

Table 1 Refractive indices (at 365 nm) and thickness of the silica coatings and viscosity of the sols

Weight ratio of PFG to silica/%	Silica coatings	Viscosity of silica sols<br/>/ (×10^-3, Pa•s)	Weight ratio of PHFBMA to silica/%	Silica coatings	Viscosity of silica sols<br/>/(×10^-3, Pa•s)
	Refractive index (n)	Thickness /nm			Refractive index (n)	Thickness /nm
0	1.226	64.2	1.52	6.8	1.245	65.6	1.53
				13.2	1.263	67.6	1.53
				26.4	1.271	69.0	1.54
1	1.212	75.4	1.56
2	1.204	86.1	1.66
4	1.195	98.7	1.75	6.8	1.203	59.1	1.37
				13.2	1.210	61.4	1.44
				26.4	1.230	63.5	1.50
6	1.177	106.9	2.05

Fig. 2 FIB-SEM images of the coatings (a) Pure silica coating with a magnification of 150,000; (b) 4wt% PFG-containing silica with a magnification of 150,000

Fig. 3 Surface morphologies of coatings (a) Pure silica coating; (b) 4wt% PFG containing silica coating; (c) 4wt% PFG containing silica coating modified by 26.4wt% of PHFBMA

Fig. 4 Transmittance spectra of AR coatings (a) Pure silica (1.65wt%) and silica with different content of PFG; (b) Pure silica (1.65wt%) with different content of PHFBMA; (c) 4wt% PFG containing silica with different content of PHFBMA

Fig. 5 Surface roughness of the coatings (a) Pure silica; (b) 26.4wt% PHFBMA-containing silica; (c) 26.4wt% PHFBMA-containing silica with PFG

Fig. 6 Water contact angle values of silica coatings without and with 4wt% of PFG vs PHFBMA concentration

Fig. 7 Changes in maximum transmittance as function of test time (a) In a closed container with 75% relative humidity at 25℃; (b) In a vacuum chamber of 0.15 MPa

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