A study of cryostructuring of polymer systems. 45. Effect of porosity of dispersed filler on physicochemical characteristics of composite poly(vinyl alcohol) cryogels

Cryostructuring of Polymeric Systems. 55. Retrospective View on the More than 40 Years of Studies Performed in the A.N.Nesmeyanov Institute of Organoelement Compounds with Respect of the Cryostructuring Processes in Polymeric Systems

“…are of significance. Both manual measurements and computer-assisted approaches have been used for the mathematical treatment of the images obtained with the aid of various types of microscopy (optical [ 170 , 171 , 172 , 206 , 225 , 230 , 231 , 232 , 233 , 234 , 237 , 238 , 240 , 241 , 243 , 244 , 245 , 246 , 250 , 251 , 252 , 256 , 257 , 258 , 259 , 261 , 262 , 263 , 264 , 265 , 267 , 268 , 269 , 270 , 272 , 380 , 383 , 384 , 390 , 393 ], laser confocal [ 369 , 370 , 371 , 372 , 392 ], and SEM [ 173 , 174 , 177 , 179 , 181 , 182 , 184 , 196 , …”

“…Of course, such usual filler-associated influence, as the growth of the mechanical strength of the composites with an increase in the content of the solid filler, providing good compatibility of discrete and continuous phases, has been observed also for the composite cryogels, in the most cases for the PVA-based ones. For instance, it was so for similar cryogels formed in a frozen aqueous medium with simultaneous its filling with the small mineral particles of sufficiently hydrophilic silica [ 205 , 225 ], titania [ 205 ], marble, and coquina [ 206 ]. At the same time, when the filler was more hydrophobic and only limitedly compatible with the continuous phase, the particulate matter formed agglomerates and did not cause marked reinforcement of the resultant composites [ 206 ].…”

“…For instance, it was so for similar cryogels formed in a frozen aqueous medium with simultaneous its filling with the small mineral particles of sufficiently hydrophilic silica [ 205 , 225 ], titania [ 205 ], marble, and coquina [ 206 ]. At the same time, when the filler was more hydrophobic and only limitedly compatible with the continuous phase, the particulate matter formed agglomerates and did not cause marked reinforcement of the resultant composites [ 206 ]. However, if the composite PVA cryogels filled with hydrophobic particles (not only inorganic, but also the organic ones like the cross-linked polystyrene [ 224 ]) were prepared in the medium of the frozen organic solvent DMSO, the phase compatibility was good enough.…”

“…However, if the composite PVA cryogels filled with hydrophobic particles (not only inorganic, but also the organic ones like the cross-linked polystyrene [ 224 ]) were prepared in the medium of the frozen organic solvent DMSO, the phase compatibility was good enough. As a result, the particulate matter was uniformly distributed within the cryogel bulk, and the reinforcement effect was pronounced [ 206 ]. Thus, these examples highlight the importance for the properties of the final composites of the filler and the cryogel compatibility, which facilitates the tight adhesion between the discrete and continuous phases.…”

“…The principal significance for the properties of the cryogenically-structured composite materials was shown to be the porosity of the filler phase [ 196 , 205 , 206 , 261 ]. When the size of the pores in the particles of the dispersed filler is wide enough for the penetration of the precursor molecules, the subsequent cryogenic structuring will proceed not only within the space of the continuous phase, but also inside the discrete phase, thus yielding the formation of the network-in-network structures.…”