Highly efficient phase transfer catalyst supported on Janus composite particles: Synthesis, characterization, and applic
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Longhui Zheng, Baoling Chen, Junhui He, and Haibin Huang College of Material Science and Engineering, Fujian Normal University, Fuzhou 350007, China
Jinhuo Lin College of Material Science and Engineering, Fujian Normal University, Fuzhou 350007, China; and Fujian Key Laboratory of Polymer Materials, Fuzhou 350007, China (Received 25 March 2014; accepted 15 May 2014)
Groups of chloromethyl were randomly grafted to Janus composite particles and quaternization was carried out on the particles. The Janus material of titania–quaternary ammoniated poly(vinylbenzyl chloride–divinylbenzene) (TiO2–QApoly(VBC–DVB)) was investigated in detail. Results revealed that the anisotropic Janus material containing quaternary ammonium groups was synthesized successfully. The Janus material could be used as the phase transfer catalyst. The catalytic activity of the Janus material was confirmed by the esterification reaction of benzyl chloride and sodium acetate. In the presence of 0.5 wt.% (relative to benzyl chloride) of TiO2–QApoly(VBC–DVB), the esterification yield of benzyl acetate reached 87.6% when the molar ratio of sodium acetate anhydrous to benzyl chloride was 1.2. The catalyst exhibited a high activity and had no obvious loss of activity when recycled three times. Moreover, the Janus material was easily recovered by centrifugation and washed with ethanol and water.
I. INTRODUCTION
Janus referred to the two-faced Roman god originally. De Gennes described the colloid particles with different chemical composition in his 1991 Nobel lecture.1 Since then, physicochemical investigations were opened up about the study of Janus particles. Janus particles have being attracting tremendous attention due to their dual anisotropy with two distinct sides.2–6 The two sides may differ in amphiphilic, optical, catalytic, electrical, and magnetic properties.7–9 Janus particles have great promise for molecular recognition,10 optical sensors,11,12 asymmetric catalysis,13 functional solid surfactants,14,15 etc. In the past years, studies on Janus materials were mainly focused on their synthesis and properties particularly.7,16–19 However, there was rarely research on Janus composite particles involving the application, especially in catalyst. Phase transfer catalysts had widely applications in the reaction of two or more immiscible phases mutually.20–22 There are many types of phase transfer catalysts, such as onium salt, crown ether, polyethylene glycol, and triphase catalysis. However, the key challenge in application of phase transfer catalysts is separation and recovery of the catalysts.23,24 Polymer-supported phase transfer catalysts are especially promising application because of their character-
II. EXPERIMENT A. Materials
Ethanol, NaOH, trimethylamine (approximately 33% in water), azobisisobutyronitrile (AIBN), magnesium sulfate anhydrous, sodium acetate, and benzyl chloride were
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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2014.117 J. Mater. Res., Vol. 29, No. 11, Jun 14, 2014
http://journ
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