Abstract:

A series of well-defined polydimethylsiloxane-b-poly(ethylene oxide) (PDMS-b-PEO)  amphiphilic diblock copolymers were synthesized by the combined use of anionic ring-opening polymerization of hexamethylcyclotrisioxane (D3) with n-butyllithium as the initiator and hydrosilation between Si—H terminated PDMS and ally terminated PEO homopolymers. The structures of PDMS and amphiphilic diblock copolymers PDMS-b-PEO were verified by nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy analyses. The diblock copolymers showed monomodal gel permeation chromatography (GPC) traces which indicated narrow molecular weight distributions (MWDs). Additionally, the solution properties of these diblock copolymers were investigated using tensiometry and transmission electron microscopy (TEM) . The equilibriumsurface tension γ and critical micelle concentration (cmc) of PDMS-b-PEO in an aqueous solution was also investigated. Interestingly, the cmc increases as the length of the hydrophobic chain increases. Transmission electron microscopy showed that PDMS-b-PEO diblock copolymers in the aqueous solution self-assembled into various morphologies including spheres, rods, and vesicle aggregates.

Key words: Diblock copolymers, Amphiphilic, Polysiloxanes, Surface tension, Self-assembly