Materials Chemistry and Physics 113 (2009) 933–936 Contents lists available at ScienceDirect Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys Synthesis and characterization of a mesoporous silica microsphere from polystyrene N. Venkatathri ∗ , S. Nanjundan Department of Chemistry, Anna University, Chennai 600 025, Tamil Nadu, India article info Article history: Received 31 January 2008 Received in revised form 16 August 2008 Accepted 19 August 2008 Keywords: Polystyrene Mesoporous Silica nanosphere abstract Even though there are several methods available in literature to synthesis mesoporous silica nanosphere, the method suitable for cosmetic applications is none. There are two different methods are known for possible encapsulation of ultraviolet ray absorber (2,2 ′ ,4,4 ′ -tetrahydroxy benzophenone). They are pre- and post-synthesis modification. In this report, we have succeeded by pre synthesis modification. Further, we have used polystyrene and cetyltrimethylammonium chloride as template for the first time to synthesis mesoporous silica nanosphere. The synthesized material was characterized by several physicochemical techniques. The results show that the synthesized material is mesoporous, which can hold good number for ultraviolet ray absorber. © 2008 Elsevier B.V. All rights reserved. 1. Introduction Nanometer to micrometer-sized materials is widely used in different areas of process industries. There are several research focused on the preparation of nanospheres. This is an important class of materials science having applications in the field of deliv- ery of encapsulated products for cosmetic and medical purposes to their use as lightweight composite materials and as fillers with low dielectric constant in electronic components [1]. Applications for silica nanospheres also cover areas such as catalysis, acoustic insulation, piezoelectric transducers and manufacture of advanced materials [2]. Various materials have been used for the prepara- tion of nanospheres, for example, polymers, glasses, metals and ceramics [1]. The methods currently used to fabricate a wide range of stable spheres include nozzle reactor processes, emulsion/phase separation, sol–gel processing and sacrificial core techniques [1]. The latter involves the use of cores that are coated with the mate- rial interest. The core is subsequently dissolved or volatilized by heating, leaving the shell of the desired hollow microsphere. The fabrication of hollow spheres has been greatly impacted by the layer by layer (LbL) self-assembly technique. This method allows the construction of composite multilayer assemblies based on the electrostatic attraction between nanoparticles and oppo- sitely charged polyions [3–9]. An important extension of the method is the preparation of multilayers of colloids on three- dimensional substrates. For example, polystyrene beads were ∗ Corresponding author. Tel.: +91 9486565702. E-mail address: venkatathrin@yahoo.com (N. Venkatathri). coated with homogeneous layers of colloidal silica particles [10,11]. LbL-coated colloidal spheres of 640 nm comprising layers of titania or silica were used for the preparation of macroporous structures [12]. In the present study, the polystyrene and cetyltrimethylammo- nium chloride were employed as template for the preparation of mesoporous silica nano structures. The material synthesized by this method was used for cosmetic applications by pre synthesis mod- ification. Further the material was also characterized by various physicochemical techniques. 2. Experimental Mesoporous silica nanospheres were synthesized by the following method. The reaction mixture was prepared by mixing 34.4ml tetraethyl orthosilicate (98%, Aldrich, USA), cetyltrimethylammonium chloride (3.96 ml, CTACl, 25%, Aldrich, USA) and polystyrene suspension (90 ml, 4.8%) in the polyethylene bottle at 298 K and stirred vigorously for 24h. The resulting solids were collected by centrifugation, washed with ethanol–water (1:1, v/v) mixture solution and dried at 333K for 12h. Surfactant micelles were partly removed by washing with 0.1 M HCl–EtOH, filtering and drying in an oven. The rest of surfactant and polystyrene spheres were com- pletely removed by subsequent calcination in air at 823 K for 8 h at a heating rate of 1.5 K min -1 to obtain hollow core silica capsules. The polystyrene spheres used in the above synthesis were prepared by follow- ing method. It was prepared by dispersion polymerization of styrene in water with potassium per sulfate as initiator. A 250-ml three-necked round bottomed flask, equipped with a mechanical stirrer, a condenser and connection with a nitrogen reservoir was used. The monomer solution was prepared by mixing 20 ml of styrene with 78 ml of water in the flask at 343 K. Potassium per sulfate (2 g) was dissolved in the above monomer solution. Polymerization was carried out under nitrogen atmo- sphere by stirring (350 rpm) the mixture solution at the temperature 343 K for 4 h. The resulting polystyrene suspension was centrifuged and the residue was collected (spherical shape, 300 nm diameter) and used for mesoporous silica nanosphere synthesis. 0254-0584/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.matchemphys.2008.08.072