Synthesis and Phase Behavior of New Amphiphilic PEG-Based Triblock Copolymers as Gelling Agents for Lamellar Liquid Crystalline Phases

Abstract

We report the first evidence of the potential of new amphiphilic ABA-triblock copolymers as gelling agents for lamellar liquid crystalline L R phases. Recently, we described a new type of lamellar hydrogels which are not based on a polymer network swollen in water but are obtained by the addition of small amounts of a nonionic polymer surfactant to the fluid lamellar LR phase of the dimyristoylphosphatidyl-choline(DMPC)/pentanol/water system. In contrast with these previously reported gelling agents which were all AB-diblock copolymers, the novel ABA-triblock copolymers consist of double chain hydrophobic moieties (A) attached to each end of a poly(ethylene glycol) chain (B). The synthesis of these new macromolecules and their gelation properties are described. The comparison of these novel lamellar hydrogels with those based on the AB-diblock copolymers provides direct evidence for the existence of cross-bridging conformations of the ABA-triblock copolymers between adjacent membranes.

Functional Liquid‐Crystalline Assemblies: Self‐Organized Soft Materials

“…[16,273] Hydrogels of lyotropic lamellar phases have been prepared by the addition of block molecules which act as a crosslinker between the layers. [274,275] These hydrogels show potential as new types of supramolecular bioactive materials for drug-delivery or tissue-healing applications.…”

Funktionelle flüssigkristalline Aggregate: selbstorganisierte weiche Materialien

“…[16,273] Hydrogele aus lyotropen lamellaren Phasen entstanden aus Blockmolekülen durch Zugabe eines physikalischen Vernetzers, der die Schichten miteinander verbindet. [274,275] Abbildung 26. Das Amphiphil 77 bildet eine quasiferroelektrische Struktur.…”

Applications

“…It has been proposed that this forms a porous structure from a percolating array of ionic clusters swollen by water dispersed in a continuous polymeric matrix. 253 ' 254 Gelation is observed with as little as 0.5% added amphiphilic block copolymer. 251,252 Won et al have shown that cross-linking PS-b-PB-b-PS copolymers prior to sulfonation enables the swelling of the membrane, and hence ionic channel size, to be controlled.…”

“…25 Lipid membranes decorated with block copolymers 253. (a) Amphiphilic AB diblocks in mushroom conformations, (b) ABA triblock copolymer in bridging conformation, (c) ABA triblock copolymer in looping conformation.…”