Self-Assembly and Structural Analysis of Multiblock Poly(oxyalkylene) Copolymers

Abstract

The self-assembled structures of newly synthesized, low molecular weight poly(oxyalkylene) block copolymers in aqueous solution were investigated using scattering methods. Diblock copolymers were synthesized using methoxy poly(ethylene glycol) 1100 as the hydrophilic block and poly(propylene oxide), poly(butene oxide), and poly(hexene oxide) as the hydrophobic moieties. The ratios of hydrophile to hydrophobe were 1:2, 1:1, and 2:1. In the cases of tri- and tetrablock copolymers, the total hydrophile to hydrophobe ratio was kept constant, at 1:1, and the same hydrophilic block was used each time. The ratios of hydrophobic moieties were varied among the tri- and tetrablock copolymers (which contained two and three types of hydrophobic units respectively). These products self-assemble in aqueous solution to give micelles or irregular aggregates with very broad size distributions. Dynamic light scattering and small-angle X-ray scattering were used as tools to determine the size and structure of these self-ass...