Lyotropic Liquid Crystalline Structures Formed by Amphiphilic Heteroarm Star Copolymers

Abstract

Polystyrene/poly(ethylene oxide) heteroarm star copolymers (i.e., star-shaped polymers consisting of a central poly(divinylbenzene) core bearing an equal number of short polystyrene and long poly(ethylene oxide) arms, PS 10PEO10) were synthesized by anionic polymerization, and their phase behavior was investigated in aqueous solutions as well as in water-oil solvent mixtures. Because of their amphiphilic character and despite their star architecture, these polymeric species self-assemble under equilibrium conditions into lyotropic liquid crystalline structures.

Fabrication of polymeric nano‐objects using PS5P2VP5 heteroarm star copolymers as building elements

“…Therefore, passing from a dilute solution to the dry state (film), the gradual increase in concentration should account for the transformation of the micellar morphology from spheres to cylinders. The fact that the predominant morphology of PS n PEO n heteroarm star copolymers in highly concentrated solutions is that of cylindrical assemblies organized in a two‐dimensional hexagonal lattice corroborates the aforementioned assumption 26. Indeed, as the spherical micelles approach each other upon densification, P2VP‐arm intermicellar (from adjacent cores) attractive interactions are possible by retraction of the PS arms leading to the formation of micelles of cylindrical morphology.…”

Transformations of Thermosensitive Hyperbranched Poly(ionic liquid)s Monolayers

“…Temperature-induced transition in mechanical properties has been also observed for the polymer surface grafted with PNIPAM brushes. The collapse of PNIPAM chains above LCST causes increase in adhesion and elastic modulus as a result of the combination of dehydration and chain entanglement. − Moreover, the incorporation of asymmetric composition of functional terminal groups can produce interesting morphologies by shifting the phase boundaries. − For example, hyperbranched polyethers possessing homogenous peripheral chemical composition did not self-organize into ordered structures, while hyperbranched polyethers partially terminated with benzoyl groups formed macroscopic aggregates . However, to date, the majority of HBPIL studies focused on the synthesis and morphologies of HBPILs composed of symmetric chemical composition ,,− with less attention paid to the assembly of HBPILs at interfaces. , It has been shown that amphiphilic branched polymers at the air–water interface exhibit interesting morphological transition upon lateral compression. ,− For example, poly­(styrene)- block -poly­(acrylic acid) dendrimer-like copolymers underwent “pancake-to-brush” transition under compression .…”

Synthesis of Amphiphilic Heteroeight-Shaped Polymer Cyclic-[Poly(ethylene oxide)-b-polystyrene]2 via “Click” Chemistry

“…Usually, the amphiphilic polymers, those composed of hydrophilic PEO block, have been used as models to study the microphase separation in bulk and self-assembling behavior in solution because of the nonionic and highly crystalline nature of PEO. Various of polymers consisting PEO block have been successfully synthesized, including the linear, , star-shaped, , and graft-shaped , polymers, in which the PEO block was typically introduced by direct and simple ROP of EO monomer or coupling reactions using a monofunctional PEO. Similarly, a library of monocycle PEOs have also been realized. , However, concerning the selective introduction of a PEO block into a heteroeight-shaped polymer, there was still some difficulties in selecting a functional initiator for ROP of EO monomer as well as screening a heterofunctional PEO for coupling methods.…”