Micropores and their interplay with liquids are critical in many solid systems but challenging to investigate, often requiring complex and indirect techniques to even be detected. Here we perform low-field 1 H NMR transverse relaxometry on submicron Stöber silica spheres to directly detect micropore water. Colloidal crystals with a well-defined spheres configuration are used to facilitate unambiguous distinction of the interparticle voids water and enable straightforward micropore volume quantification. We evidence significant microporosity (~16% of the sphere volume) with high water-accessibility and monitor the drying of the micropore water, which exhibits high resilience, evaporating only after complete voids drainage. Progressive microporosity closure by thermal annealing above 600 ºC is shown, until complete removal at 900 ºC. Increasing hydrophobicity of the micropore walls is observed, although it barely affected the water access. Our results prove the capability of NMR relaxometry to quantitatively investigate complex microporosity and the behavior of water confined therein.

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Low‐field nuclear magnetic resonance techniques are employed to extract information about the effects introduced by the interaction with the surface on the rotational and translational dynamics of molecules confined inside a mesoporous carbon xerogel. The molecules under study were water, cyclohexane, and hexane. They were chosen due to their different interaction strength with the carbonaceous matrix. Frequency dependent longitudinal relaxation measurements, using the fast field cycling technique, allowed extraction of the fractal dimension of the carbon xerogel surface. It was observed that the measured value is influenced by the molecule affinity to the surface. Diffusion measurements, using the pulse field gradient technique, have revealed that the stronger interaction with the surface of cyclohexane and hexane molecules leads to an increased diffusive tortuosity, as compared with water.