Presentation on theme: "Fabrication and Evolution of Mesostructures in Fluorinated Organosilicate Mesoporous Thin Films Ji-In Jung, Jae Young Bae and Byeong-Soo Bae* Department."— Presentation transcript:
Fabrication and Evolution of Mesostructures in Fluorinated Organosilicate Mesoporous Thin Films Ji-In Jung, Jae Young Bae and Byeong-Soo Bae* Department of Materials Science and Engineering, KAIST, Daejeon , Republic of Korea * Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology (KAIST) Introduction PFASs with long perfluoroalkyl chains act as a structure directing agent. Different interaction with templates cause the different mesostructure formation range. The chain length of PFASs affected the formation of mesostructure and thermal- induced mesostructure change. The increase of calcination temperature caused the change of the composition, mesostructure, and optical property in the mesoporous fluorinated organosilicate films. Conclusions Experiments Self-Assembly of Surfactants 0.01N HCl Add methanol Filtering & spin coating Heat treatment TMOS PFASs 3-FPTMS 13-FOTES 17-FDTMS Surfactants for Experiment Experimental Purposes Fluorinated mesoporous organosilicate films Mesoporous silica films PFASs with perfluoroalkyl groups Synthesis of fluorinated mesoporous organosilicate films with surfactants and chain lengths of PFASs Physical characteristics of fluorinated films depending on chain lengths of PFASs and kind of surfactants → Optical property (n) & hydrophobicity & formation scheme Thermal induced mesostructure and composition change XRD Patterns of the Films Confirmation of Perfluoroalkyl Groups PFASs Chain Length Effect Fabrication of Films with Pluronic F68 Thermal-Induced Mesostructure Change Future Works Kind of Mesoporous Structures Used in membrane, sensor, and optical and electroni devices. → Investigation of microstructure, composition and optical property in the fluorinated organosilicate films Evaporation Induced Self-Assembly (Film) Experimental Routes PFASs Unit cell parameter /nm Contact angle / o Mesoporous structure Refractive index As- synthesized Calcined 3-FPTMS Hexagonal1.268 Cubic FOTES Hexagonal FDTMS Hexagonal1.240 PFASs with long perfluoroalkyl chain act as templates! PFASs, the Role of Templates Fabrication of Films with CTACl XRD Patterns of the Films Thermal Analysis of the Films XRD patterns Comparison of Mesostructure Formation Formation Scheme Possibilities for a variety of application in optics ! The increase calcination temperature cause the decomposition perfluoroalkyl groups. References (a)1060 cm -1 Asymmetric stretching mode of Si-O-Si bond (b) 1146 cm -1 Bending mode of Si-CH 2 of perfluoroalkylsilane (c) 1206 cm -1 Symmetric stretching mode of C-F bond of perfluoroalkyl chain Mesoporous fluorinated organosilicate thin films were calcined at 350 o C. 17-FDTMS 3-FPTMS 13-FOTES Substrate F68(Cubic) Substrate P123 (Hexa) Substrate F68 (Cubic) P123 (Hexa) Substrate 100 nm 91 nm 133 nm HexagonalCubicLamellar Cubic Amphiphilic surfactant Hydrophilic head Group Hydrophobic tail Surfactant concentration increase Micelle Burn off surfactant Surfactant + Inorganic precursor (Silica et al.) Formation of Mesoporous Materials Inorganic-Organic Hybrid Mesoporous Materials Stirring for 24 hr Add surfactant TMOSPFAS N HCl CH 3 (CH 2 ) x N(CH 3 ) 3 ]Cl [CH 3 (CH 2 ) x N(CH 3 ) 3 ]Cl CTACl (x=15) Alkyl-ammonium halide cationic surfactant Hydrophilic head group Hydrophobic tail group PEO : Hydrophilic (water-soluble) PPO : Hydrophobic (water-insoluble) PEO-PPO-PEO triblock copolymer Pluronic F68 (N=153, M=29) Spherical micelle After calcined [ CTACl ] / [ TMOS ] (x263) H C H H HHHH Silica 3-FPTMS 13-FOTES 17-FDTMS H CC HHHH H H HC*C H H H : Hexagonal C : Cubic C* : Hexagonal/Cubic Fluorinated Mesoporous Silica Mesoporous [Surfactants] / [Silanes] CTACl F68 CTACl F68 J.I. Jung; J.Y. Bae; B.S. Bae J. Mater. Chem. To be submitted (2004). J.I. Jung; J.Y. Bae; B.S. Bae Chem. Mater. To be submitted (2004). J.Y. Bae; J.I. Jung; B.S. Bae J. Mater. Res. To be submitted (2004). J.Y. Bae; O.H. Park; J.I. Jung; K.T. Ranjit; B.S. Bae Micropor. Mesopor. Mater. 67, 265 (2004). O.H. Park; S.Y. Seo; J.I. Jung; J.Y. Bae; B.S. Bae J. Mater. Res. 18, 1039 (2003). C.J. Brinker; Y. Lu; A. Sellinger; H. Fan Adv. Mater. 11, 579 (1999). A. Stein; B.J. Melde; R.C. Schroden Adv. Mater. 12, 1403 (2000). G. Wirnsberger; B.J. Scott; B.F. Chmelka; G.D. Stucky Adv. Mater. 12, 1450 (2000). FT-IR spectroscopy As-synthesized After calcinedFT-IR spectroscopy Pluronic F68 copolymer decomposes above 350 o C. Mesoporous fluorinated organosilicate thin films were calcined at 400 o C. TGA Curves Silica wall Fluorinated group Although surfactant concentration is very low, mesoporous films are mainly formed by long perfluoroalkyl chain (As template). Mesostructure Changes Compositional Change Refractive Index Change 20nm 3-FPTMS and CTACl After calcination at 550 o C, the cylindrical pores are maintained. 350 o C550 o C 20nm 17-FDTMS and CTACl After calcination at 550 o C, a less ordered and broken mesostructure was formed. 350 o C550 o C Multi-mesostructured Films Photochromic Dye - Applicable for optical waveguide, shutters, light modulators, and optical storage media - For optical shutter applications, a fast response time is required. - Study about the effect of hydrophobicity and pore size OH HO OH HO CF n FnCFnC FnCFnC FnCFnC Fast response time & long switching cycle is expected. It is possible to form the multi-layered films with thickness and different pore surface property such as pore size and pore structure. [Multi-layer with different pore size and pore structure] As-synthesized F68 used repulsion - The repulsion of hydrophobic perfluoroalkyl chain & hydrophilic PEO chain. CTACl used hydrophobic interaction - The hydrophobic interaction of hydrophobic chain of CTACl & hydrophobic perfluoroalkyl chain.