Hierarchical Micellar Structures from Amphiphilic Invertible Polyesters: ¹H NMR Spectroscopic Study

Abstract

The environment-dependent behavior of invertible polyesters has been studied by 1H NMR spectroscopy. In dilute toluene solutions, the micelle exterior is made up of the lipophilic fragments, and the interior consists of the hydrophilic constituents. The polyester inverts the structure in an aqueous medium to form micelles with a hydrophobic inner part and a hydrophilic outer part. Increasing polyester concentration leads to the formation of hierarchical structures both in toluene and in an aqueous medium as a result of the aggregation of unimolecular micelles and the formation of hydrophilic and lipophilic domains. On the contrary, no unimolecular micelles or micellar aggregation has been observed in acetone or chloroform.

Solvent-Responsive Self-Assembly of Amphiphilic Invertible Polymers Determined with SANS

“…Our recent 1 H NMR spectroscopy study 32,33 shows that selfassembled AIP macromolecules undergo conformational changes in solvents whose polarity strongly differs. This makes the micellar assemblies responsive to the changing polarity of the environment.…”

“…28−34 We observed that, in dilute polymer solutions in toluene, the exterior of the micelles is made of lipophilic(CH 2 ) n  moieties, and the interior consists of polar PEG fragments. 32 In turn, micelles with a hydrophobic inner part and a hydrophilic exterior are formed in AIP aqueous solution ( Figure 1B). With increasing polymer concentration, the hydrophilic and hydrophobic domains are formed in toluene and an aqueous medium as a result of unimer aggregation.…”

Amphiphilic invertible polymers for adsolubilization on hydrophilic and hydrophobized silica nanoparticles

“…The AIPs form micelles, self-assemble (form hierarchical micellar architectures) in solvents strongly differing by polarity and switch conformation upon changing environment polarity [48][49][50][51][52][53][54][55]. It has been demonstrated that, being self-assembled in solvents differing by polarity, AIPs can accommodate otherwise non-soluble molecules in the micellar interior.…”

Invertible Micellar Polymer Nanoassemblies Target Bone Tumor Cells But Not Normal Osteoblast Cells

“…However, AIP macromolecules undergo rapid inversion of macromolecular conformation, due to subtle changes in the polarity of the environment [24,27]. Once the curcumin-loaded IMAs from PEG 600 PTHF 650 reach the cell surface sites (less polar than aqueous medium), drug release is induced by the conformational changes of the AIP macromolecules [28].…”