Supramolecular Assemblies of Amphiphilic Homopolymers

Abstract

Amphiphilic molecules self-assemble in solvents because of the differential solvation of the hydrophilic and lipophilic functionalities. Small-molecule surfactants have long been known to form micelles in water that can solubilize lipophilic guest molecules in their water-excluded interior. Polymeric surfactants based on block copolymers are also known to form several types of aggregates in water owing either to the mutual incompatibility of the blocks or better solvation of one of the blocks by the solvent. Incorporating amphiphilicity at smaller length scales in polymers would provide an avenue to capture the interesting properties of macromolecules and fine tune their supramolecular assemblies. To address this issue, we designed and synthesized amphiphilic homopolymers containing hydrophilic and lipophilic functionalities in the monomer. Such a polymer can be imagined to be a string of small-molecule surfactants tethered together such that the hydrophilic and lipophilic functionalities are located on opposite faces, rendering the assemblies facially amphiphilic. This feature article describes the self-assembly of our amphiphilic homopolymers in polar and apolar solvents. These homopolymers not only form micelles in water but also form inverse micelles in organic solvents. Subtle changes to the molecular structure have been demonstrated to yield vesicles in water and inverted micelles in organic solvents. The characterization of these assemblies and their applications in separations, catalysis, and sensing are described here.

Polymeric Surfactants: Synthesis, Properties, and Links to Applications

“…322,323 The most common kinds of polysoaps for which surface properties have been investigated are based on amphiphilic derivates of acrylamide or acrylic acid and on hydrophibically modified polysaccharides. Other systems include homopolymers of polymerizable surfactants 320,324 or random copolymers of hydrophobic and hydrophilic monomers. 325 The hydrophobic monomer can also be pH-responsive.…”

Temporal and Triggered Evolution of Host–Guest Characteristics in Amphiphilic Polymer Assemblies

“…3 On the other hand, the possibility of pre-programming self-assembly characteristics in the monomer stage itself has attracted interest in amphiphilic homopolymer systems. 4 Since these amphiphiles are simply the polymerized versions of the corresponding small molecules, there exists a structural continuum between these two molecular classes in the form of oligomers. In this context, we study the host-guest characteristics and morphological evolution of assemblies made from low molecular weight polymeric amphiphiles in response to their depolymerization towards monomeric amphiphile (Scheme 1).…”

Aptamer-Mediated Targeted Delivery of Therapeutics: An Update

“…When the ratio of hydrophobic and hydrophilic components in copolymers is appropriate, they could self-assemble into micelles in an aqueous environment [111,112]. Micelles as drug carriers show very interesting properties, including high solubility and bioavailability of hydrophobic drugs in water, long-term stability in blood and slow drug release rate.…”