Synthesis and self-assembly of H-shaped amphiphilic block copolymer based on polyoxyethylene, polyoxybutylene, and poly(ε-caprolactone) units

Abstract

In this research, a new amphiphilic copolymer with an H-shaped macromolecular structure consisting of three hydrophobic blocks and two hydrophilic blocks were synthesized by a combination of ring-opening polymerization and click chemistry. The central chain and two of the side arms of the H-shaped structure were made of oxybutylene and hexanoate repeating units, respectively (hydrophobic segments). The remaining two side arms are made of oxyethylene repeating units (hydrophilic segments) that are connected to the rest of the structure through disulfide bonds. The prepared H-shaped macromolecules were characterized by elemental analysis (CHNS), FT-IR, and 1H-NMR techniques. Based on transmission electron microscopy (TEM) images, the amphiphilic nature of the H-shaped polymer allowed it to form spherical molecular assemblies with a mean diameter of about 80 nm. The critical micelle concentration (CMC) in an aqueous solution was determined using the fluorometric method (CMC = 4.76 × 10−3 mg/mL). According to the profiles obtained from dynamic light scattering (DLS), the resulting spherical micelles had a mean hydrodynamic diameter ( H ) of ∼95 nm with a low polydispersity index (PDI = 0.26).