Cryogels crosslinker concentration

Fig. 13 Gel-fraction yield plotted against temperature for chitosan cryogels crosslinked using glutaraldehyde. Polymer concentration in the initial solution was 1.6 wt%. NH2-to-CHO molar ratio was 2.5 1 (curve 1), 15 1 (curve 2) and 25 1 (curve 3). (From [10] with permission from Springer)...

Fig. 15 Temperature dependence of the gel-fraction yield during the preparation of poly(styrene) gels (circles) and cryogels (squares) in nitrobenzene using 4,4 -xylylene dichloride as a crosslinker. The temperature scale is the relative temperature AT (as explained in Sect. 1). Polymer and crosslinker concentrations in the initial nitrobenzene solution were 0.3 M and 9.1 mol%, respectively (both with respect to the styrene units). (Plotted based on the data from [27])...

Fig. 2 Optical microscopy images of cryogel beads, (a) Ionic PAAc cryogel beads formed at — 18 °C. rom [73] with permission from Elsevier), (b) Frozen PIB solution droplets in liquid nitrogen, and (c) crosslinked PIB beads just after preparation. S2CI2 = 20 % (v/w) PIB concentration = 10 % (w/v). (From [69] with permission from Elsevier). Scale bars 2 mm...

Using (8), one may estimate the polymer concentration i/ in the unfrozen gel phase at a given temperature Tprep (Tprep < Tf ). To apply (8) to the cryogelation systems, we assume that the monomers completely accumulate in the unfrozen reaction phase before the onset of gelation. We also assume that, after cryogelation, the conversion of mraiomer to crosslinked polymer is complete. Thus, the monomer concentration C in the unfrozen zones (in % w/v) can be estimated from i/ as ... 

Ivanov RV, Lozinsky VI, Noh SK, Han SS, Lyoo WS (2007) Preparation and characterization of polyacrylamide cryogels produced from a high-molecular-weight precursor. I. Influence of the reaction temperature and concentration of the crosslinking agent. J Appl Polym Sci... 

---