Synthesis of composite eccentric double-shelled hollow spheres Jianjun Li, Shujiang Ding, Chengliang Zhang * , Zhenzhong Yang * State Key Laboratory of Polymer Physics and Chemistry, Beijing National Laboratory of Molecular Science, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China article info Article history: Received 8 March 2009 Received in revised form 2 June 2009 Accepted 5 June 2009 Available online 11 June 2009 Keywords: Eccentric structure Double-shelled Hollow spheres abstract Eccentric double-shelled hollow polyethylacrylate (PEA)/polystyrene (PS) crosslinked composite spheres were synthesized by phase separation during swelling polymerization of their mother polymer hollow spheres. The group –NH 2 was introduced within the network by ammonization of PEA. Other materials for example silica could be favorably grown within the gel network by a sol–gel process. The polymer/ silica hollow spheres gave the corresponding derivative hollow spheres with varied composition including SiO 2 /carbon, carbon and b-SiC, with the eccentric double-shelled morphology retained. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Hollow spheres have attracted considerable attention owing to their potential applications in many fields, such as catalysis, lightweight fillers, controlled release and dye-sensitized solar cells [1–4]. A diversity of hollow spheres of varied composition, such as organic, inorganic and metal, has been successfully prepared [5–16]. They have shown interesting properties. For example, SiO 2 /carbon hybrid ones can strongly absorb solar light of a broadening wavelength range, and can be in-situ loaded with noble metal nanoparticles with improved electronic properties [17–19]. Recently, complex concentric multi-layered hollow spheres are becoming more interesting for their unique plasma properties [20–23]. We have previously prepared those complex composite hollow spheres using polymer hollow spheres as templates [24–26]. For instance, composite functional hollow spheres with double concentric shells are synthesized using sandwiched hydrogel hollow sphere templates [25]. Compared with the concentric hollow spheres, those eccentric double-shel- led hollow spheres have fascinating different characteristics. For example, silica-Au eccentric nanoegg fabricated by anisotropic electroless plating, has different multiple-peaked plasmonic response [27]. Eccentric sphere-in-sphere titanium hollow spheres can scatter UV light more effectively inside the cavity so as to greatly enhance photocatalytic activity [28]. It should be noticed that the inner sphere is not fixed thus movable, the unique properties will become unstable upon external mechanical vibration. Development of a facile approach to large scale production of eccentric double-shelled hollow spheres with fixed inner sphere is required. Herein, we report the synthesis of eccentric double-shelled hollow composite spheres using the corresponding ammonized gel hollow sphere templates. As illustrated in Fig. 1 , a commercial polystyrene (PS) hollow sphere with transverse hydrophilic chan- nels is selected as an example mother template [25]. The swelling monomers of ethyl acrylate (EA) and divinylbenzene (DVB) can easily diffuse into the cavity via the channels while simultaneously swelling the shell from both the interior and exterior surfaces. At a high content of crosslinking agent DVB, polymerization induced viscoelasticity can drive asymmetric phase separation resulting in anisotropic sandwiched hollow spheres. After dissolution of the middle layer, eccentric double-shelled hollow spheres are derived. Some functional groups for example -NH 2 can be introduced within the eccentric hollow spheres by modifying the PEA network through ammonization, which are conducive to further growth of other functional materials. By a sol–gel process forming silica within the gel region, the corresponding silica/polymer composite hollow spheres are derived. Due to the presence of crosslinked network from DVB, the polymer can be easily converted into carbon resulting eccentric silica/carbon double-shelled hollow spheres. For all the double-shelled hollow spheres, the inner sphere is fixed onto the outer shell thus not movable. * Corresponding authors. Fax: þ86 10 62559373. E-mail addresses: zhangcl@iccas.ac.cn (C. Zhang), yangzz@iccas.ac.cn (Z. Yang). Contents lists available at ScienceDirect Polymer journal homepage: www.elsevier.com/locate/polymer 0032-3861/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.polymer.2009.06.008 Polymer 50 (2009) 3943–3949