Surface behavior and micelle morphology of novel nonionic polyurethane bolaform amphiphilic block copolymers

A novel series of nonionic bolaamphiphiles-polyurethane amphiphilic block copolymers were synthesized by addition polymerization. Their chemical structures were characterized using FTIR and H-1-NMR spectra. The critical micelle concentration was determined by surface tensiometer and UV-vis absorption spectra. The surface behaviors of copolymers at air/water interface were also investigated including the effects of concentration, molecular structure, electrolytes, and rest time. The results show that these bolaform polyurethane amphiphilic block copolymers exhibited excellent surface activity: PU34 could attain surface tension as low as 35.6 mN m(-1). According to the images of Transmission Electron Microscopy (TEM), the copolymers could self-assemble star-like aggregates comprised of hydrophobic block PPO surrounded by hydrophilic block PEO. Moreover, variation of concentration, the weight fraction of the hydrophilic block (f(phil)), and the molecular weight of the copolymers could lead to the transformation of micelle (or premicelle) morphology. This provides a new and simple way to obtain nanoparticles with control over structure on the nanometer scale.