Phase Behavior and Polymerization Kinetics of a Semifluorinated Lyotropic Liquid Crystal

Abstract

Recently, amphiphilic monomers that are capable of forming lyotropic liquid crystalline phases have been utilized in a variety of applications including emulsion polymerization, development of nanocomposites, and the formation of polymeric surfactants. A new class of fluorinated amphiphilic monomers that exhibit lyotropic mesophases has shown great promise in ophthalmic applications. Initial studies indicate that the monomer possesses a lamellar morphology at certain concentrations that when polymerized would yield a material with anisotropic properties ideal for repairing retinal tears. Characterization of the polymerization kinetics of these fluorinated monomers provides a better understanding of conditions such that structure retention can be obtained. The fluorinated amphiphiles exhibit varying phase morphology ranging from an isotropic micellar phase to discontinuous cubic and lamellar liquid crystalline phases with increasing concentration and variation in the percent neutralization of the acid moiety. The lyotropic liquid crystalline order changes significantly with respect to percent neutralization. The polymerization kinetics follow a trend of decreasing order with increasing neutralization in that the fastest rates are seen in samples with higher degrees of order specifically in the lamellar liquid crystalline phase. The polymerization rate decreases to a minimum in samples of cubic morphology with low degrees of overall order. The higher polymerization rates in the lamellar phase are due to a decrease in the termination rate. Additionally, the polymerization behavior and morphology have a tremendous impact on the resulting polymer.