Surface characterization of amphiphilic block copolymers possessing polyisoprene and poly [tri(ethylene glycol) methacrylate] segments and the effect of side chain ω-function on surface energy

A series of amphiphilic polyisoprene-b-poly[oligo(ethylene glycol) methyl (and tert-butyldimethylsilyl) ether methacrylate] (PIsp-b-PR3, R = methyl (M), tert-butyldimethylsilyl (Si)) diblock copolymers were prepared with varying PR3 compositions. The PIsp-b-PR3s were synthesized by the sequential anionic copolymerization of isoprene and corresponding methacrylate monomer (M3 or Si3). The obtained polymers had narrow molecular weight distributions (M-w/(Mn) <= 1.04) and predictable molecular weights. The bulk-state self-assembled nanostructure was studied by transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). We also evaluated the surface energy of PR3s having an inherent amphiphilic character by pendant drop method along with PIsp. In addition, the surface structure of the block copolymer thin films was investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) measurement. It was concluded that the estimated surface energy values (PM3 (37.3 + 0.3 (mJ/m(2))) and PSi3 (32.4 + 1.4 (mJ/m(2)))) were authentic by comparison with the observation result of surface structure and depended on side chain omega-function.