Porosity and Surface Properites of SBA-15 with Grafted PNIPAAM: A Water Sorption Calorimetry Study | Zendy

Nina Reichhardt | Zendy; Tommy Nylander | Zendy; Beate Klösgen | Zendy; Viveka Alfredsson | Zendy; Vitaly Kocherbitov | Zendy

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Porosity and Surface Properites of SBA-15 with Grafted PNIPAAM: A Water Sorption Calorimetry Study

Author(s) -

Nina Reichhardt,

Tommy Nylander,

Beate Klösgen,

Viveka Alfredsson,

Vitaly Kocherbitov

Publication year - 2011

Publication title -

langmuir

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 1.042

H-Index - 333

eISSN - 1520-5827

pISSN - 0743-7463

DOI - 10.1021/la203093u

Subject(s) - silanol , sorption , chemical engineering , porosity , calorimetry , materials science , adsorption , polymerization , poly(n isopropylacrylamide) , specific surface area , wetting , mesoporous material , enthalpy , polymer chemistry , grafting , contact angle , chemistry , polymer , organic chemistry , composite material , thermodynamics , copolymer , physics , engineering , catalysis

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.

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