Photochromic Nanofiber Aggregates of PVA/H 3 PMo 12 O 40 Hybrid
- PDF / 316,384 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 44 Downloads / 174 Views
M12.5.1
Photochromic Nanofiber Aggregates of PVA/H3PMo12O40 Hybrid Jian Gong,* Fengmei Gao, Yan Pan, Xiujun Cui, Lunyu Qu and Rongshun Wang Department of Chemistry, Northeast Normal University, Changchun 130024, China. ABSTRACT Poly (vinyl alcohol) (PVA)/H3PMo12O40 ultra-fine fiber aggregates contained differential weight percentage of H3PMo12O40 to PVA (20, 50 and 80 wt.%, respectively) have been successfully prepared by electrospinning technique. By means of IR spectrum, wide-angle X-ray diffraction, and scanning electron microscope (SEM) techniques, the fiber aggregates were characterized. The result from scanning electron microscopy (SEM) showed that the average diameter of the fibers was between 240-900 nm. The photochromic behavior of the fiber aggregates was investigated by means of IR, UV-Vis spectra and electron spin resonance (ESR). The results showed that the Mo atom of H3PMo12O40 was reduced via one-electron step and the PVA was oxidized to unsaturated ketone after the PVA/H3PMo12O40 fiber aggregates was irradiated under UV light. The color of the fiber aggregates changed from white to blue under ultraviolet irradiation and the photochromism of the fiber aggregates was reversible in air condition. INTRODUCTION Recently, polyoxometalates as the inorganic part of the inorganic-organic hybrid material have received increasing attention. Their redox property and high electronic density are ideal for use as photochromic and electrochromic materials [1,2]. R. Lu and Y. Y. Zhao groups et al. have investigated photochromic property of hybrid inorganic-organic materials contained polyoxometalates [3,4]. The results indicate these materials can be designed as candidates for a number of applications including photoelectric display, high-density memory devices and sensors. Electrospinning is a simple and efficient method for the production of scaffolds composed of nano- to microscale aggregates. We have adapted this technology in our group for the preparation of some PVA/polyoxometalates fiber aggregates and investigated the effect of polyoxometalates on swelling behavior of PVA in water [5,6]. In this paper, based on the preparation of PVA fiber aggregates contained different percentage of H3PMo12O40, we investigate the photochromic mechanism of PVA/H3PMo12O40 fiber aggregates by IR and ESR spectra of the irradiated fiber aggregates. A conceivable photochromic mechanism is suggested. EXPERIMENTAL DETAILS H3PMo12O40 was obtained from Shanghai Chemical Co., Ltd. in China. The PVA was Mn 86,000, was supplied by DC Chemical Co., Ltd. Distilled water was used as the solvent. 20 g of
M12.5.2
aqueous PVA solution of 10 wt.% was added into a certain of H3PMo12O40 (0.5, 3 and 8g, respectively) with stirring for 24 h at the ambient temperature. The PVA/H3PMo12O40 solution was placed in a plastic syringe at a fixed distance (~ 10 cm) from a metal cathode to anode. A metallic pin connected to a high-voltage generator was placed in the solution. The voltage applied between the anode and cathode was kept ca. 18 kV. Different
Data Loading...
