Thermo-reversible gelation

Beginn developed Percec-type dendrimers, which are known to form supramolecu-lar channels, with polymerizable acrylate groups in order to obtain ion-permeable membranes [97-99]. First, the dendron 78 (Scheme 40) was dissolved in a polymerizable acrylate mixture that does not shrink on polymerization. The second step was the thermo-reversible gelation of the acrylate mixture, which was followed by the last step, polymerization to fix the supramolecular channel structure (Scheme 40). In the first experiments, compounds with only one polymerizable group were used but it turned out that the gelating properties were not sufficient [100, 101] so threefold modified 78 had to be developed. 

Nunes, S. P. Wolf, B. A. Jeberien, H. E., "On the Cooccurrence of Demixing and Thermo-reversible Gelation of Polymer Solutions. 2. Thermodynamic Background," Macromolecules, 20, 1948 (1987). 

Thermo-reversible gelation takes place upon cooling of solutions in the presence and absence of gelling cations for low acyl and high acyl types, respectively. 

Bain, M.K. Bhowmik, M. Maity, D. Bera, N.K. Ghosh, S.N. Chattopadhaya, D. Control of thermo reversible gelation of methylcellulose using different molecular weight of PEG and NaCl for sustain delivery of ophthalmic drug. J. Appl. Polym. Sci. 2010,118 (2), 631-637. 

Berghmans H., (1988), Thermo reversible gelation of synthetic Polymers, Integration of Polymer Science and Technology 2, Elsevier Appl.Sci. Publ. 

Guenet, J.M., Thermo reversible Gelation of Polymers and Biopolymers. Academic Press London, 1992. 

Near the gelation threshold, the combination of thermo-reversible junctions and chain entanglements shown to stabilize the liquid jet and overcome capillary forces allowing the electrospinning. 

One interesting feature of PE solutions is the ability of PEs to form cross-linked gel networks [83, 96]. These networks can be formed either by chemical or by ionic thermo-reversible bonds formed by e.g. multivalent ions as cross-linkers [83, 97]. A Hory theory based theoretical study of the PE gelation points using di- and... 

A reverse thermo-gelation property system was generated using chitosan and glycerol phosphate di-sodium salt (Chenite et al., 2000). The aqueous solution of this mixture behaved as sol at normal temperatures and showed gel phase transition when the temperature was increased to 37 C. The structuring effect of glycerol on water... 

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