Fundamental Study of Polymer Organization at the Interfaces by the Fusion of Organic Chemistry and Physical Chemistry

点击翻译按钮获取中文摘要

Molecular properties and self-assemblies, such as micelle in water and monolayer at the air/water interface, of ionic amphiphilic diblock copolymers were systematically investigated from synthesis to nanostructure analysis.Unexpectedly, the ionic amphiphilic block copolymers shows "non-surface activity" but forms micelles in solution. Since this phenomenon is out of commonsense of surface and interface science, this polymer can be regarded as a novel substance. By investigation with block copolymer with various chain length and length ratios, the origin of the non-surface activity could be attributed to the image charge effect at the air/water interface, and the requirements to be non-surface active were quantitatively clarified. The non-surface activity is achieved by the accurate balance of three factors, polymerity, ionicity, and hydrophobicity.The polymer micelle in water shows extremely high toughness against salt addition. No aggregates were formed up to 0.5M NaCl. The structure … More transition between spherical and rod-like micelles were also observed as a function of chain length and salt concentration.The nanostructure of their polymer monolayer on the water surface was systematically investigated by X-ray and neutron reflectivity techniques. The monolayer structure is not a simple double layer of hydrophobic and hydrophilic brush layers, but is triple layer with "carpet" layer between them. The carpet layer is dense hydrophilic layer, whose thickness is almost constant at 15Å. The critical brush density for the transition between double and triple layer structures could be estimated. Also, the critical salt concentration, where nanostructure change occurs by salt addition, was found to be in the order of 10^<-1>M salt.In conclusion, the properties and self-assembling behavior of "novel substance", ionic amphiphilic diblock copolymer, could be clarified by the fusion of high techniques for precession synthesis of amphiphilic polymers and for nanostructure analysis with scattering and reflectivity. Less