Porosity and surface properties of SBA-15 with grafted PNIPAAM: A water sorption calorimetry study.

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Porosity and surface properties of SBA-15 with grafted PNIPAAM: A water sorption calorimetry study.

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Publication Article, peer reviewed scientific
Title Porosity and surface properties of SBA-15 with grafted PNIPAAM: A water sorption calorimetry study.
Author(s) Reichhardt, Nina ; Nylander, Tommy ; Klösgen, Beate ; Alfredsson, Viveka ; Kocherbitov, Vitaly
Date 2011
English abstract
Mesoporous silica SBA-15 was modified in a three-step process to obtain a material with poly-N-isopropylacrylamide (PNIPAAM) grafted onto the inner pore surface. Water sorption calorimetry was implemented to characterize the materials obtained after each step regarding the porosity and surface properties. The modification process was carried out by (i) increasing the number of surface silanol groups, (ii) grafting 1-(trichlorosilyl)-2-(m-/p-(chloromethylphenyl) ethane, acting as an anchor for (iii) the polymerization of N-isopropylacrylamide. Water sorption isotherms and the enthalpy of hydration are presented. Pore size distributions were calculated on the basis of the water sorption isotherms by applying the BJH model. Complementary measurements with nitrogen sorption and small-angle X-ray diffraction are presented. The increase in the number of surface silanol groups occurs mainly in the intrawall pores, the anchor is mainly located in the intrawall pores, and the intrawall pore volume is absent after the surface grafting of PNIPAAM. Hence, PNIPAAM seals off the intrawall pores. Water sorption isotherms directly detect the presence of intrawall porosity. Pore size distributions can be calculated from the isotherms. Furthermore, the technique provides information regarding the hydration capability (i.e., wettability of different chemical surfaces) and thermodynamic information.
DOI http://dx.doi.org/10.1021/la203093u (link to publisher's fulltext)
Publisher American Chemical Society
Host/Issue Langmuir;22
Volume 27
ISSN 0743-7463
Pages 13838-13846
Language swe (iso)
Subject(s) Nanomaterials
SBA-15
Sorption calorimetry
Porosity
Nitrogen
water sorption
Sciences
Research Subject Categories::NATURAL SCIENCES
Handle http://hdl.handle.net/2043/12861 (link to this page)

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