Synthesis of polyamine-silica hybrids by a no electrostatic surfactant assembly

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University of Dar es Salaam
Polyamine-silica hybrids (PASH) were prepared by one-pot co-condensation of tetraethoxysilane and various organosilanes at various ratios over structure directing non¬electrostatic surfactants. A systematic study was done on the suitability of the various non-electrostatic surfactants, namely, n-dodecylamine (DDA), n-hexadecylamine (HDA) and cashew nut shell liquid (CNSL). The PASH materials were characterized by a variety of techniques including acid titration, nitrogen physisorption, Scanning Electron Microscopy, Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy and Atomic Force Microscopy. The functionalization of the PASH materials was successful as revealed by DRIFT spectroscopy. The hybrids prepared over the DDA and HDA as templates had irregularly shaped particles clustered into small aggregates. Their loadings ranged from 1.0 to 3.4 mmol/g. They showed a type IVc isotherm with type H3 hysteresis loop indicative of frame-work confined pores. On the other hand, particles of the CNSL-based hybrids were roughly spherical with an average diameter of 0.5 jim. Their loadings ranged from 1.4 to 2.5 mmol/g. They showed type IVa isotherm with type HI hysteresis loop indicating that the pores were cylindrical and open at both ends. The monoamine-based CNSL- templated hybrid exhibited a wider pore size distribution with an average pore diameter of 17.6 nm. Generally, the loadings were higher at an organosilane to TEOS ratio of 1:4 than at 1:9. The surface areas ranged from 200 to 750 m2/g. The non-electrostatic surfactants were found to be suitable templates for the synthesis of PASH that have high loadings and desired porosity. The CNSL-based hybrids were found to have desirable properties similar to those of the materials prepared on commercially available templates.
Available in print form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS EAF QP801.P638.H46)
assembly, polyamine
Hilonga, A (2007) Synthesis of polyamine-silica hybrids by a no electrostatic surfactant assembly, Master dissertation, University of Dar es Salaam. Dar es Salaam.