tailieunhanh - Báo cáo hóa học: " Simple Systematic Synthesis of Periodic Mesoporous Organosilica Nanoparticles with Adjustable Aspect Ratios"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Simple Systematic Synthesis of Periodic Mesoporous Organosilica Nanoparticles with Adjustable Aspect Ratios | Nanoscale Res Lett 2009 4 1524-1529 DOI s11671-009-9430-7 NANO EXPRESS Simple Systematic Synthesis of Periodic Mesoporous Organosilica Nanoparticles with Adjustable Aspect Ratios Paritosh Mohanty Kai Landskron Received 16 July 2009 Accepted 19 August 2009 Published online 16 September 2009 to the authors 2009 Abstract One-dimensional periodic mesoporous or-ganosilica PMO nanoparticles with tunable aspect ratios are obtained from a chain-type molecular precursor octa-ethoxy-1 3 5-trisilapentane. The aspect ratio can be tuned from 2 1 to 20 1 simply by variation in the precursor concentration in acidic aqueous solutions containing constant amounts of triblock copolymer Pluronic P123. The mesochannels are highly ordered and are oriented parallel to the longitudinal axis of the PMO particles. No significant Si-C bond cleavage occurs during the synthesis according to 29Si MAS NMR. The materials exhibit surface areas between 181 and 936 m2 g-1. Keywords Periodic mesoporous organosilicas One-dimensional nanostructures Synthesis Introduction Periodic mesoporous organosilicas PMOs have emerged as a diverse class of materials 1-4 . They are composed of O2--bridged Si-R-Si building units R organic group that build periodic mesoporous frameworks. They can be prepared in surfactant-templated self-assembly processes from organosilanes of the type EtO 3Si-R-Si OEt 3. The presence of the bridging organic groups allows for the use of these organosilanes as single-source precursor without the aid of inorganic co-reactants such as tetraethoxysilane. Thus a high and homogeneous distribution of organic groups in the channel walls of these materials can be P. Mohanty K. Landskron El Department of Chemistry Lehigh University Bethlehem PA 18015 USA e-mail kal205@ achieved which renders them with attractive mechanical 5 catalytic 6 sorption 7 and dielectric 8 properties. One-dimensional 1D nanostructures such as nanowires NWs nanofibers NFs nanotubes NTs and nanorods NRs