Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants|
|Research Institution||KYOTO UNIVERSITY|
YAMAOKA Hitoshi Kyoto University, professor, 工学研究科, 教授 (80026004)
LODGE Timothy p. University of Minnesota, professor, 化学科, 教授
TIRRELL Matthew University of Minnesota, professor, 化学工学ー材料科学科, 教授
MATSUOKA Hideaki Kyoto University, Lecturer, 工学研究科, 助手 (40165783)
SAWAMOTO Mitsuo Kyoto University, professor, 工学研究科, 教授 (90150325)
|Project Period (FY)
1994 – 1995
Completed(Fiscal Year 1995)
|Budget Amount *help
¥7,200,000 (Direct Cost : ¥7,200,000)
Fiscal Year 1995 : ¥3,500,000 (Direct Cost : ¥3,500,000)
Fiscal Year 1994 : ¥3,700,000 (Direct Cost : ¥3,700,000)
|Keywords||Amphiphilic polymer / Block polymer / Living cationic polymerization / Polymer micelle / Surface activity / Small-angle neutron scattering / Small-angle X-ray scattering|
This 2-year Japan-U.S.bilateral research project has been directed to "amphiphilic polymers", or macromolecules consisting of both hydrophilic and hydrophobic moieties, for which efforts have been focused on : (a) precision sample syntheses ; (b) their behavior in solution and at surface or interface ; (c) factors affecting their hydrophilic and hydrophobic interactions ; and (d) relations between their spatial shapes and functions. A brief summary follows :
1.Synthesis of Amphiphilic Polymers
Four series of well-defined amphiphilic polymers have been synthesized by the living cationic polymerization developed by the Japanese members :
(A) AB-block copolymers of 2-hydroxyethyl and 2-phenoxyethyl vinyl ethers ;
(B) AB-block copolymers of 2-hydroxyethyl and n-butyl vinyl ethers ;
(C) Partially deuterated analogs of block copolymers A and B where the phenyl and the n-butyl pendant groups are deuterated, respectively ;
(D) Tetraarmed block copolymers of vinyl ether and stirene derivatives.
t Scattering and X-Ray Scattering Analyzes
Solubilization of hydrophobic dyes into water by these polymers confirmed that they are amphiphilic and thus form micelles, which were further analyzed by scattering methods :
(a) Dynamic light scattering (DLS) for the micelle sizes ;
(b) Forced Rayleigh scattering for the diffusion constants (by the American members) ;
(c) Small-angle X-ray scattering (SAXS) for the shape and number of the micelles.
For example, the DLS analysis (a) of the 4-arm polymers D showed their sharp response to solvent polarity, unimers in ethanol and micelles in chloroform. The SAXS data (c) for the linear polymers A and B indicated that increasing polymer concentration increases the number of micelles without changing their shapes.
3.Neutron Scattering Analysis
Small-angle neutron scattering (SANS) was applied to the partially deuterated amphiphiles C in D_2O/H_2O mixtures for the contrast variation method. Dependence of SANS profiles on the solvent composition revealed core-shell architectures of the block polymers, the shapes of which change from spherical to ellipsoidal on increasing length of the hydrophobic segments.
4.Surface and Interface Analysis
Effective surface activity of polymers A and B were shown by clear reduction of the surface and interfacial tensions of water in their presence at low concentrations. These amphiphiles also interact with silica surface ; the strength and distance of the interaction was evaluated by evanescent light wave scattering. Less