Synthesis and Solution Properties of PDMS-b-PEO Amphiphilic Diblock Copolymers

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 equilibrium surface 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.