Mesoporous Silica Formation by Block Copolymers and Cetyltrimethylammonium Bromide as Structure Control Agent

Document Type : Research Paper

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Abstract

Block copolymers and cetyltrimethylammonium bromide were used as templates in nano silica structure formation like MCM-41)Mobil Composition of Matter), SBA16 )Santa Barbara Amorphous) and a new compound namely SPB  )silicone mesoporous particles, prepared by sol-gel method using PPG-PEG-PPG block copolymer) to compare the porosity and regularity of the products together. In this work tetraethylorthosilicate  )TEOS), as silica source and alcohol as surface modifying agent were used because of having the main advantage, compared to an ionic template such as etyltrimethylammonium bromide, in producing larger pores  and thicker walls for holding larger catalytic molecules in their pores or increasing  their resistance towards fragmentation. In order to study the copolymer as a template,  SPB structure was prepared and compared with SBA16 which was found to have  broader  pore-size  distribution  and  smaller  specifc  surface  area.  Using  alcohol  in particle production resulted in higher formation rate of micelles with improved  morphology. Nitrogen adsorption-desorption, X-ray diffraction and electron scanning  microscopy confrmed the mesoporous structure and regularity of these synthesized  materials. Finally a mechanism is proposed for the formation of these structures.

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Iranian Journal of Polymer Science and Technology
Volume 24, Issue 6 - Serial Number 6
March and April 2012
Pages 445-453

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