Stimuli-Responsive Shapeshifting Mesoporous Silica Nanoparticles

Abstract

Stimuli-responsive materials have attracted great interest in catalysis, sensing, and drug delivery applications and are typically constituted by soft components. We present a one-pot synthetic method for a type of inorganic silica-based shape change material that is responsive to water vapor exposure. After the wetting treatment, the cross-sectional shape of aminated mesoporous silica nanoparticles (MSNs) with hexagonal pore lattice changed from hexagonal to six-angle-star, accompanied by the loss of periodic mesostructural order. Nitrogen sorption measurements suggested that the wetting treatment induced a shrinkage of mesopores resulting in a broad size distribution and decreased mesopore volume. Solid-state (29)Si nuclear magnetic resonance (NMR) spectroscopy of samples after wetting treatment displayed a higher degree of silica condensation, indicating that the shape change was associated with the formation of more siloxane bonds within the silica matrix. On the basis of material characterization results, a mechanism for the observed anisotropic shrinkage is suggested based on a buckling deformation induced by capillary forces in the presence of a threshold amount of water vapor available beyond a humidity of about 50%. The work presented here may open a path toward novel stimuli-responsive materials based on inorganic components.

Recyclable Nanoporous Materials with Ordered Tunnels Self‐Assembled from α‐ and γ‐Cyclodextrins

“…Porous materials, such as covalent organic frameworks (COF), [1,2] Metal-organic frameworks (MOF), [3,4] zeolites, [5,6] mesoporous silica, [7,8] aerogels, [9][10][11] and sponges, [12,13] have received considerable attentions in recent years due to their crucial applications in gas storage, absorption, separation, catalysis, sensing, energy, thermal insulation, and biomedicine etc. The physical properties and applications of the porous materials mostly rely on their pore parameters, [14,15] such as pore size, pore volume, porosity, regularity, and dispersity, [16][17][18] and can be tuned by different synthesis methods.…”

Analytical Understanding of the Materials Design with Well‐Described Shrinkages on Multiscale

“…A strong Q 4 signal illustrates that silicate species are highly crosslinked to S−O−Si bonds. Such densified frameworks with crosslinked Si−O−Si bonds usually possess higher thermal stability …”

“…Such densified frameworks with crosslinked SiÀOÀSi bonds usually possessh igher thermals tability. [33,35] Figure 1. SEM images of as-made polymer/silica opala nd poroussilica films after anisotropic shrinkage(reproduced with permission from Ref.…”

Large-scale preparation of macro-porous silica microspheres via sol–gel composite particles and a spray drying process

“…), different composite particles could be obtained. [24][25][26] However there exist certain limitations in this method. First, the sol-gel reaction must be conducted in solvent and the separation/collection of nal products would be difficult; secondly, the porous structure is mesoporous and the precise structure could not be controlled.…”