Cryostructuring of Polymeric Systems. 50.† Cryogels and Cryotropic Gel-Formation: Terms and Definitions

Abstract

A variety of cryogenically-structured polymeric materials are of significant scientific and applied interest in various areas. However, in spite of considerable attention to these materials and intensive elaboration of their new examples, as well as the impressive growth in the number of the publications and patents on this topic over the past two decades, a marked variability of the used terminology and definitions is frequently met with in the papers, reviews, theses, patents, conference presentations, advertising materials and so forth. Therefore, the aim of this brief communication is to specify the basic terms and definitions in the particular field of macromolecular science.

Flow-Through Catalytic Reactors Based on Metal Nanoparticles Immobilized within Porous Polymeric Gels and Surfaces/Hollows of Polymeric Membranes

“…As distinct from hydrogels, cryogels synthesized in cryogenic conditions can consist of interconnected macroporous matrices with the pore size from ∼ 0.1 to 10 μm and supermacroporous matrices with the pore size in the range from several tens to several hundreds of micrometers [23][24][25]. Due to high surface/volume ratio and easy convection of liquids inside cryogel matrices, both macroporous and supermacroporous cryogels are proved to be the most favorable materials to design flow-through catalytic reactors [7,26,27] (Figure 7).…”

Ultralight magnetic aerogels from Janus emulsions

“…Freeze-drying is a well-established approach to obtain so-called "cryogels". [17][18][19][20] A rapid freezing rate leads to smaller pore size, whereas a slow rate is accompanied by larger pore dimensions. The low-temperature process is of special relevance for biomedical applications.…”

“…The low-temperature process is of special relevance for biomedical applications. 17,21 However, for some special applications, a macroporous aerogel is required to accelerate transport processes into the 3D structure. For example, biosensors related applications demanded signicantly larger pore sizes to immobilize bacteria.…”

Supermacroporous polydivinylbenzene cryogels with high surface area: Synthesis by solvothermal postcrosslinking and their adsorption behaviors for carbon dioxide and aniline

“…Cryogels are a type of supermacroporous materials of interconnected micrometer-scale porous structures obtained from crosslinking of monomeric or polymeric precursors via either covalent interactions, or noncovalent interactions, or ionic interactions at freezing temperatures below the melting point of the solvent and pore formation with solvent crystals. [1][2][3] Compared to poly high internal phase emulsions (HIPEs), another class of supermacroporous materials, cryogels are "green" and easy of preparation mainly due to free of any surfactant. 4,5 Moreover, owing to a unique cryoconcentration effect in the cryotropic gel formation, the porogens can reach up to 90% relative to the total volume, allowing for high porosity and low density of cryogels.…”