Invertible Amphiphilic Homopolymers

Abstract

Stimuli-responsive polymers and assemblies are viable candidates for the so-called "smart" materials. In this communication, we report a new class of amphiphilic homopolymers that forms micelle-like structures in polar solvents and inverted micelle-like structures in apolar solvents. We demonstrate that these superstructures are the result of the changes in the molecular-level conformations in the monomer.

Supramolecular Assemblies from Amphiphilic Homopolymers: Testing the Scope

“…3 We have recently developed a molecular design based on homopolymers in which both the hydrophilic and the hydrophobic moieties are incorporated within the monomer unit. 4 In that preliminary communication, we had demonstrated that such homopolymers are capable of providing both micelle-like and inverse micelle-like assemblies depending on the solvent environment, which is an amplified consequence of the molecular level conformational changes in each monomer unit. Since then, we have shown that such polymer assemblies are indeed unique and therefore could find complementary applications in a broad range of areas.…”

An Amphiphilic Molecular Basket Sensitive to Both Solvent Changes and UV Irradiation

“…A molecular basket was obtained by linking four cholate units to a cone-shaped calix [4]arene scaffold through azobenzene spacers. The molecule turns its polar faces inward in nonpolar solvents to bind polar molecules such as sugar derivatives.…”

“…Azobenzene-derived calixarenes have attracted considerable interest of supramolecular chemists 9 ever since Shinkai and coworkers discovered the autoaccelerative diazo coupling of calix- [4]arene. Many calixarenes with azobenzene at the upper rim have been prepared according to Shinkai's method.…”

“…Many calixarenes with azobenzene at the upper rim have been prepared according to Shinkai's method. 11 To ensure a basket-like conformation, we prefer to have the calix [4]arene scaffold preorganized into the cone conformation by alkyl substitution at the lower rim. 3a However, with one exception, 11e nearly all previously reported azocalixarenes have unsubstituted hydroxyl groups para to the azobenzene groups.…”

Macroporous materials by self-assembly of linear oligo(phenylsilsesquioxanes).

“…That low stability can be attributed to hydrogen bonding interactions between alcohol molecules and residual hydrophilic silanol moieties in the material. The literature reports evidence similar phenomena, leading to the formation of spherical structures with a random-coil backbone conformation, for oligomers with large aromatic [58,59], dendritic [60] or amphiphilic [61,62] side groups. Analogously, rigid rodflexible coil block copolymers can self-assemble in selective solvents into specific nanostructures with morphology governed by the geometric disparity between the rod and coil segments and anisotropic interactions between rod blocks (formation of liquid crystalline or crystalline structures) [63,64].…”