Abstract
A simple photolysis route was proposed to prepare Amphiphilic Janus Particles (AJP) based on SiO2 microspheres. The surface of SiO2 microspheres were modified by photoactive alkoxysilane, which was synthesized by dealcoholization condensation of 6-nitroveratroyloxycarbonyl and isocyanatopropyl-triethoxysilane. UV irradiation caused eater-breaking allowed for the precise control of hydrophilic modification of the hemispherical exposed particles surfaces. The component and morphology of the obtained particles were characterized by fourier transform infrared spectroscopy and ultraviolet-visible spectroscopy, and the Janus feature was evaluated by scanning electron microscopy, transmission electron microscopy, and dispersity in the oil–water dual-phases. The following results were obtained. The AJP with 450 nm size processes the hydrophilic amino groups on one side and the hydrophobic 6-nitroveratryloxycarbonyl moieties on the other. Additionally, the AJP were located at the phase boundary between water and n-hexane, and the negative charged gold nanoparticles with 25 nm size were adsorbed only onto the side with the positive charged amino groups. The AJP have interfacial adsorption energies that can be as much as three times larger than that of homogeneous particles and thus exhibit excellent surface activities.
Highlights
Janus particles, first coined by Pierre-Gilles de Gennes in his 1991 Nobel Lecture, are named after the two-faced Roman god to depict the particles with two different properties on each side [1]
Inspired by the NVOC protecting strategy, we present a simple method for fabricating functional sub-micron sized SiO2 amphiphilic Janus particles (AJP) with chemically reactive amino groups
Tetrahydrofuran (THF), n-hexane, trisodium citrate dehydrate, ethanol, NH3·H2O and methylbenzene were obtained from Aladdin. 3-mercaptopropionic acid (MPA) and HAuCl4·4H2O were purchased from Aldrich
Summary
First coined by Pierre-Gilles de Gennes in his 1991 Nobel Lecture, are named after the two-faced Roman god to depict the particles with two different properties on each side [1]. Since the concept was presented, the various Janus particles with different surface components, structures or compartments on both sides have attracted extensive interest for their anisotropic chemical, optical, electronic, and magnetic properties [2,3,4]. Even this concept has been extended to the field of dendrimers with asymmetric structures. The amphiphilic Janus particles (AJP) of this article, composed of hydrophilic and hydrophobic hemispheres, are some of the simplest anisotropic colloids, and they exhibit higher surface activities than particles with homogeneous surface properties. AJP have interfacial adsorption energies that can be as much as three times larger than that of homogeneous particles and exhibit excellent surface activities [9,10]
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