Delivered by Ingenta to: Nanyang Technological University IP: 5.101.219.235 On: Mon, 20 Jun 2016 23:25:23 Copyright: American Scientific Publishers Copyright © 2009 American Scientific Publishers All rights reserved Printed in the United States of America Journal of Nanoscience and Nanotechnology Vol. 9, 4623–4632, 2009 Preparation and Supramolecular Self-Assembly of Amphiphilic Dendron-POSS Nanohybrids Gung-Pei Chang 1 , Ru-Jong Jeng 1 , Shenghong A. Dai 1 , and Ying-Ling Liu 2 ∗ 1 Department of Chemical Engineering, National Chung Hsing University, Taichung 42025, Taiwan 2 R&D Center for Membrane Technology and Department of Chemical Engineering, Chung Yuan Christian University, Chungli, Taoyuan 32023, Taiwan Organic/inorganic urea/malonamide dendron-POSS nanohybrids with different generations of den- drons and peripheral groups were prepared. Chemical structures of the nanohybrids were characterized with FTIR, 1 H NMR, molecular mass spectrometry, and elemental analysis. The nanohybrids exhibited better solubility in organic solvents as compared to their corresponding den- drons. Self-assembled layered dendron/POSS structures were observed for the nanohybrids with the low generation dendrons, as evidenced by TEM analysis. The nanohybrids also exhibited amphiphilic property because of the hydrophilicity of urea/malonamide dendrons. Moreover, the morphologies of the nanohybrids could be tailored via using various casting solvents. Keywords: Dendrimer, Dendron, POSS, Nanohybrid. 1. INTRODUCTION Materials in nanometer-scale structures have attracted great attentions in scientific researches. Inorganic materi- als in the shapes of nanowires, nanoparticles, nanotubes, and nano-lamellas were prepared and widely studied. Organic–inorganic nanocomposites, in which the organic and inorganic components were mixed in nanometer- scale, were also investigated extensively. The prepared nanocomposites usually demonstrate properties superior to the conventional composite materials. On the other hand, organic nanomaterials, which have well-defined structures and nanometer-scale sizes, are also of inter- est. In one example, the organic nanoparticles are derived from the self-assembly of amphiphilic copolymers. 1–5 The prepared nanoparticle sizes are not specific and unique, and usually in hundreds of nanometers. Another exam- ple is dendrimers, which are macromolecules having well- defined structures and unique molecular weights. The multi-functional peripheries of dendrimers bring wide physical and chemical diversities to dendrimers and extend their scopes of application potentials. 6–10 Based on the unique characteristics and properties of den- drimers, it is sensible to prepare dendrimer-based organic- inorganic nanocomposites. For example, dendrimers were utilized as organic modifiers for lamellar clays. 11–15 The spacial distances of the modified clays are tunable, ∗ Author to whom correspondence should be addressed. dependent on the generations of dendrimers. 14 15 In addition, dendrimer-entrapped metal nanoparticles were extensively investigated. 16–23 The ratios of the numbers of dendrimer molecules to those of nanoparticles in the nanohybrids could be fine-tuned to adjust the properties of the nanohybrids. Dendrimer-carbon nanotubes (CNT) 24 25 and dendrimer-C 60 26–28 nanohybrids were also prepared to bridge the unique characteristics of dendrimers and the carbon nanomaterials in one molecule. In preparation of nanomaterials, polyhedral oligomeric silsesquioxane (POSS) derivatives represent a promis- ing breed of building blocks. 29–31 Three-dimensional, rigid, and cubic-shaped POSS cores provide nearly per- fect nano-blocks, whereas their peripheral multi-functional organic moieties bring chemical diversity to POSS deriva- tives. As a result, several dendrimer-POSS nanohybrids were reported. 32–36 Most of the reported dendrimer-POSS nanohybrids consisted of the multi-functional POSS cages as the core units, from where the dendrons were either grown divergently or convergently. 32–34 Moreover, Dvornic et al. 35 reported an unique dendrimer-POSS nanohybrid possessing peripheral POSS cages. The ratios of organic to inorganic fraction in the organic/inorganic nanohybrids would play an important role of influencing their physi- cal properties. Therefore, a new class of dendron-POSS nanohybrids is reported in this work, in which a POSS cage would be covalently bonded with a dendron unit. The properties of these dendron-POSS nanohybrids are highly dependent on the dendron generation and peripheral J. Nanosci. Nanotechnol. 2009, Vol. 9, No. 8 1533-4880/2009/9/4623/010 doi:10.1166/jnn.2009.1280 4623