TY - JOUR

T1 - The influence of drying and calcination on surface chemistry, pore structure and mechanical properties of hierarchically organized porous silica monoliths

AU - Putz, Florian

AU - Waag, Anna

AU - Balzer, Christian

AU - Braxmeier, Stephan

AU - Elsaesser, Michael S.

AU - Ludescher, Lukas

AU - Paris, Oskar

AU - Malfait, W. J.

AU - Reichenauer, Gudrun

AU - Hüsing, Nicola

PY - 2019/11/1

Y1 - 2019/11/1

N2 - Hierarchically organized, porous materials exhibit unique combinations of physical and chemical properties depending on their pore sizes, pore structure and surface chemistry. Extraction and drying methods as well as post synthetic thermal treatments influence the characteristics of the resulting porous network and thus the achievable properties. Here we present a comprehensive investigation of the effects of drying conditions and post synthesis treatments on surface chemistry, pore structure and resulting mechanical properties of hierarchically structured silica monoliths comprising pores on three hierarchy levels (micro-, meso- and macropores). Samples were either dried supercritically (SCD) with carbon dioxide or at ambient pressure (APD) after surface silylation. In addition, the impact of a post synthetic heat treatment at two different temperatures (300 °C and 500 °C) is investigated. The focus of the study is on chemical and structural changes in/at the (meso-)pore walls, including the presence of micropores and the influence of organic components on the macroscopic properties. We discuss the implications of these modifications on mechanical properties, such as their deformation behavior during fluid adsorption related to their respective bulk and skeletal Young's moduli. Scanning electron microscopy, nitrogen adsorption/desorption measurements, simultaneous thermal analysis, solid-state NMR spectroscopy, small-angle X-ray scattering, sound velocity measurements and nitrogen adsorption/desorption with in-situ dilatometry were performed on each sample. This set of data illustrates the significant impact of different fabrication steps such as drying or calcination on material properties.

AB - Hierarchically organized, porous materials exhibit unique combinations of physical and chemical properties depending on their pore sizes, pore structure and surface chemistry. Extraction and drying methods as well as post synthetic thermal treatments influence the characteristics of the resulting porous network and thus the achievable properties. Here we present a comprehensive investigation of the effects of drying conditions and post synthesis treatments on surface chemistry, pore structure and resulting mechanical properties of hierarchically structured silica monoliths comprising pores on three hierarchy levels (micro-, meso- and macropores). Samples were either dried supercritically (SCD) with carbon dioxide or at ambient pressure (APD) after surface silylation. In addition, the impact of a post synthetic heat treatment at two different temperatures (300 °C and 500 °C) is investigated. The focus of the study is on chemical and structural changes in/at the (meso-)pore walls, including the presence of micropores and the influence of organic components on the macroscopic properties. We discuss the implications of these modifications on mechanical properties, such as their deformation behavior during fluid adsorption related to their respective bulk and skeletal Young's moduli. Scanning electron microscopy, nitrogen adsorption/desorption measurements, simultaneous thermal analysis, solid-state NMR spectroscopy, small-angle X-ray scattering, sound velocity measurements and nitrogen adsorption/desorption with in-situ dilatometry were performed on each sample. This set of data illustrates the significant impact of different fabrication steps such as drying or calcination on material properties.

KW - hierarchical porosity

KW - hybrids

KW - in-situ dilatometry

KW - mechanical properties

KW - post synthesis treatments

U2 - 10.1016/j.micromeso.2019.109578

DO - 10.1016/j.micromeso.2019.109578

M3 - Article

AN - SCOPUS:85066610591

VL - 288.2019

JO - Microporous and Mesoporous Materials

JF - Microporous and Mesoporous Materials

SN - 1387-1811

IS - 1 November

M1 - 109578

ER -