Synthesis and Properties of Amphiphilic Polymers

这一为期两年的日美双边研究项目针对的是“两亲性聚合物”，即由亲水和疏水部分组成的大分子，其努力集中在：(A)精确的样品合成；(B)它们在溶液中和在表面或界面上的行为；(C)影响它们亲水和疏水相互作用的因素；以及(D)它们的空间形状和功能之间的关系。1.两亲性聚合物的合成日本成员开发的活性阳离子聚合合成了四种定义明确的两亲性聚合物：(A)2-羟乙基和2-苯氧乙基乙烯基醚的AB-嵌段共聚物；(B)2-羟乙基和正丁基乙烯基醚的AB-嵌段共聚物；(C)分别含有苯基和正丁基的嵌段共聚物A和B的部分氚类似物；(D)乙烯基醚和苯乙烯衍生物的四臂嵌段共聚物。2.Ligh…更多的t散射和X射线散射分析这些聚合物将疏水染料溶解到水中证实它们是两亲性的，从而形成胶束，并通过散射方法进一步分析：(A)胶束大小的动态光散射(DLS)；(B)扩散常数的强迫瑞利散射(美国成员)；(C)胶束形状和数量的小角X射线散射(SAXS)。例如，对四臂聚合物D的DLS分析(A)表明它们对溶剂极性、乙醇中的单体和氯仿中的胶束反应强烈。对线型聚合物A和B的SAXS数据(C)表明，随着聚合物浓度的增加，胶束的数量增加，但不改变它们的形状。3.中子散射分析采用小角中子散射(SANS)对D_2O/H_2O混合物中的部分氚两亲分子C进行对比度变化法。SANS谱对溶剂组成的依赖关系揭示了嵌段聚合物的核-壳结构，其形状随着疏水链段长度的增加而从球形变为椭圆形。4.表面和界面分析聚合物A和B的有效表面活性表现为在低浓度时，水的表面和界面张力明显降低。这些两亲分子还与二氧化硅表面相互作用；相互作用的强度和距离通过消逝光波散射来评估。较少

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 PolymersFour 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.2.Ligh … More t Scattering and X-Ray Scattering AnalyzesSolubilization 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 AnalysisSmall-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 AnalysisEffective 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