solution of PVA and the polymer additive can be frozen while in a homophase
liquid state. As the pure ice is initially crystallized, both polymeric components are
concentrated in the UFLMP. This cryo-concentration process causes liquid–liquid
phase separation within the volume of the unfrozen inclusions. In the second case,
the initial common solution of PVA and the polymeric additive can undergo liquid–
liquid separation prior to the cryogenic treatment, a behavior inherent in the wellknown Albertsson’s liquid two-phase polymeric systems [188], so that the already
formed two coexisting liquids are frozen. Certainly, there can be some intermediate
variants because the phase segregation in viscous polymer solutions occurs rather
slowly, i.e., the process is kinetically controlled.
An example of the first case is the preparation of macroporous PVA cryogels in
aqueous solutions of PVA in the presence of poly(ethylene glycol) of molecular
Fig. 20 (continued)
Basic Principles of Cryotropic Gelation
89
liquid state. As the pure ice is initially crystallized, both polymeric components are
concentrated in the UFLMP. This cryo-concentration process causes liquid–liquid
phase separation within the volume of the unfrozen inclusions. In the second case,
the initial common solution of PVA and the polymeric additive can undergo liquid–
liquid separation prior to the cryogenic treatment, a behavior inherent in the wellknown Albertsson’s liquid two-phase polymeric systems [188], so that the already
formed two coexisting liquids are frozen. Certainly, there can be some intermediate
variants because the phase segregation in viscous polymer solutions occurs rather
slowly, i.e., the process is kinetically controlled.
An example of the first case is the preparation of macroporous PVA cryogels in
aqueous solutions of PVA in the presence of poly(ethylene glycol) of molecular
Fig. 20 (continued)
Basic Principles of Cryotropic Gelation
89