摘要
提出了测定胶束质量分维的两种新方法即粘度法和GPC－LALLS联机法，随后从动态光散射数据计算了离子型胶束SDS的分维，这些实验数值之间能互相印证．建立了放束形成过程的Laplace分形理论，计算得分维D＝1．54（二级），作高级计算的分维D＝1．67与前面实测值基本相符，另外，从唯象理论角度，讨论了胶束的多重分形及其热力学行为，发现有两个相变点βc＝-4和βc＝-1．并认为这两个转折分别对应着单分子分形胶束经典胶束结构之间的转变．
The Mark-Houwink equation [η] =KWα is used to determine the mass fractal dimensions of Ancelles. Here [η] being intrinsic viscosity, M beging molecular weight of micellar cluster.K, α, constants. The viscosity exponent α=(3/D-1), and the fractal dimension D may be obtained by ln[η]-InM plot, e.g. D=1.73 for Brij 35 in water and D=1.68, 1.62 for polyepichlorohydrin in tetrahydrofuran (THE) and cyclohexanone.To determine with easy the fractal dimensions of micelles and macromolecules, a new approach, dubbed GPC-LALLS (gel permeation chromatography coupled with LALLS),has been work out by us, and the value of fractal dimnsion for polyepichlorohydrin in THF obtained by GPC-LALLS is 1.667. The results indicate that the micellar clusters resemble the DLA. According to the Laplace fractal approach. The theoretical values of fractal dimensions of micellar clusters are obtained as D=1.54 (second order). D=1.67(higer or der) in agreement with computer sinuilation. In the same time. the multifractal spectrum f(α)-α of micelles are obtained and fmax(α)= 1.75.The multifractal thermodyndcs is employed to study the formation and transition of micelle. The partition function is defined as Z(β.L)=∑α Cα ∑i Pi,a β where Cα is the weight of configuration α. Pi, α is the growth probability of site i of configuratin α,L is the system size, and β is the parameter measuxing the heterogeneity of surfactant aggrega tion. Thereby two transition points, βc=-4. βc=-1, for micelle aare found and set βc=-4 corresponds the transition between surfactants and fractal micelles. and βc=-1 , the tran sition between fractal micelles and Euclidean structuxes (.i. e. spherical, cylindrical, layer micelles etc.). These transitions correspond to the Brigg(50-50A). Porod(50-200A) and Guinier(200-1000A).
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
1994年第3期241-246,共6页
Acta Physico-Chimica Sinica
基金
国家教委优秀年轻教师基金
四川省青年基金
关键词
胶束
分形
多重分形
相变
Micelles, Fractals, Multifractals, Phase transition
