Unfrozen liquid microphase

The chosen solvent must crystallize rather than vitrify under the cryostracturing conditions otherwise, if the solvent imdergoes a glass transition, the unfrozen liquid microphase will not form and, hence, no cryo-concentrating effects will take place. This requirement is also valid for any other precursor system to be gelled cryogenic ally. 

As for the systems discussed in Sect. 2.2, the requirement of a good solubility of the high molecular weight precursors in the medium of the unfrozen liquid microphase is also important. If a decrease in the temperature and resulting freezing of the... 

Keywords Cryotropic gelation Unfrozen liquid microphase Freezing Frozen storage Defrosting... 

Cryotropic gel formation is a liquid-phase process occurring in the unfrozen liquid microphase of a macroscopically frozen system. 

Due to concentrating of solutes in the unfrozen liquid microphase, an apparent decrease in the critical concentration of gelation is observed in cryotropic gel formation as compared to gelation at positive temperatures... 

The solutions with PVA content 0 = 0.086, and 0.12 form a gel upon defrosting after 390 min at —13 °C (curve c of Fig. 16b). However, the solution with 0 = 0.042 is unable to jellify upon the same cryotropic treatment [77]. This indicates that for polymer concentrations below a critical value, the total volume of the unfrozen liquid microphase is too low to form cluster aggregates [77]. The clustering process, in turn, plays a key role in formation of the gel. 

Incomplete solvent crystallization occurring at subzero temperatures, with consequent formation of an unfrozen liquid microphase of eutectic composition... 

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