Predictable Shrinkage during the Precise Design of Porous Materials and Nanomaterials

Abstract

The advent of ordered porous materials and nanomaterials with controlled porosity has opened new frontiers in the field of materials chemistry. Materials with ordered micro-, meso-, and macropores, including hierarchical pores, provide exceptional functions that make them suitable for uses in a wide variety of advanced device materials, media for electrochemical phenomena, and components for sophisticated functional products. In the fabrication of ordered porous structures that would enhance the function of materials, the shrinkage of frameworks plays a vital role in the formation of unique structures of porous materials and nanomaterials. To reveal the role of isotropic and anisotropic shrinkages in the process of pore construction, this review provides an overview of previous experiments that have focused on such framework shrinkages of highly porous materials prepared using organic templates and further assesses how shrinkages (isotropic for particles and anisotropic for films) are fascinating for porous materials design. This type of study will stimulates new strategies on the emerging challenges and opportunities to utilize high-grade and predictable design for obtaining nanomaterials including unique porous materials of relevance in multiple areas such as energy.

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

“…Thermally induced contraction influences af inal morphology of materials. [1] For example, the thermal treatment to remove a triblock copolymer (i.e.,P EO-PB-PEO) from iridium oxide (IrO 2 ) films results in au niaxial (anisotropic)s hrinkage of film and pores perpendicular to substrate. [99] The shrinkage induced by thermalt reatment at high temperature also impacts the surface groups and porosity of the films.…”

“…Our latestr eview article provided the relationship between framework shrinkages and resultant morphologies of periodic porousm aterials and further design to obtain uniformly arranged nanoparticles. [1] Isotropic changes in nanoscale are reflected in the decrease of the geometrical volume (particle size) of powder samples. Owing to ac onfininge ffecto fs ubstrate, anisotropics hrinkage can incur ad eviation in the shape of pores in the shrinking direction of film.…”

“…All of the investigations are crucial to encourage the utilization of such shrinkages for the precise design of nanomaterials. In this review, we summarize significant works how to analyze shrinkages in multiscale during the synthesis of materials, which will be useful as a follow‐up review to our latest contribution . Well‐defined porous materials are also selected as a good candidate for understanding well‐described shrinkages.…”

“…In this review, we summarize significant works how to analyze shrinkages in multiscale during the synthesis of materials, which will be useful as af ollow-up review to our latest contribution. [1] Well-defined porous materials are also selected as ag ood candidate for understanding well-described shrinkages. This review aims to provide ad etailed glimpse of the development of analyses on shrinking behaviors in multiscale for the materials design.…”

Toward compositional design of reticular type porous films by mixing and coating titania-based frameworks with silica

“…Thus, in this study, spherical PS-b-PEO aggregates were eliminated by an UV-ozone treatment for 15 min (twice) that also induced an enough substantial shrinkage of the titania frameworks for the formation of reticular type porous structures, as well as calcination below 550 • C. 18,20 Shrinkage of oxide frameworks is quite important for the prediction of resultant porous structures, which has been recently reviewed for the precise design of porous materials and nanomaterials. 23 According to my literatures, [18][19][20] reticular type porous titania films have so far been provided using PS n -b-PEO m having the molecular weight of (n, m) = (100 000, 150 000) and (12 200, 23 900) which was purchased from Polymer Source, Inc. All solvents (THF-tetrahydrofuran and EtOH-ethanol) were obtained from Wako Chemical Co. For the direct synthesis of a pure titania film, 19 titanium tetraisopropoxide (TIPP, 0.422 g) was pre-hydrolyzed by adding concentrated hydrochloric acid (concentrated HCl, 0.231 ml) under vigorous stirring. After being stirred for 10 min, the solution was added to a solution containing colloidal PS-b-PEO aggregates (0.50 g in THF; 8.0 g, EtOH; 2.0 g and total H 2 O; 2.0 ml).…”