Study of Dielectric Normal Mode Process in Semidilute and Concentrated Solutions of Polymers.

通常，介质正模过程的数据提供了端到端距离均方< <r^2> >和端到端矢量波动的弛豫时间<tau_n>两个信息。利用该技术研究了< <r^2> >和<tau_n>在顺式聚异戊二烯（cis-PI）半稀和浓溶液中的浓度C依赖性，并与静态和动态标度规律进行了比较。在<theta>的溶剂二氧六环中，< <r^2> >与预期的浓度无关，而在良好的溶剂苯中，我们发现< <r^2> >的C依赖性有四个不同的浓度区域，即稀(I)、半稀（II）、半浓（II'）和浓（III）状态。在状态II中，< <r^2> >与<C^(-1/5)>成比例变化，符合标度理论。在区域II'中，< <r^2> >的C依赖性用Edwards理论定性解释。在正十六烷和具有边际溶剂质量的1-二十烯的顺式pi溶液中也观察到类似的行为。利用低分子量顺式pi溶液的数据，将松弛时间<tau_n>降为等摩擦状态<tau_(n zeta)>。苯和二恶烷中的<tau_(n zeta)>分别与<C^(1.3)>和<C^(1.6)>成正比。这些依赖关系只能用de Gennes提出的动态标度理论来定性地解释。排除体积效应和水动力效应对弛豫时间的分布影响不大。

Generally, the data of dielectric normal mode process provide two informations, i.e. the mean square end-to-end distance < <r^2> > and the relaxation time <tau_n> for fluctuation of the end-to-end vector. Using this technique, we studied the concentration C dependence of < <r^2> > and <tau_n> in semidilute and concentrated solutions of cis-polyisoprene (cis-PI) and compared them with the static and dynamic scaling laws.In a <theta> solvent dioxane, < <r^2> > was found to be independent of concentration as expected, while in a good solvent benzene, we found four concentration regions differing in the C dependence of < <r^2> >, i.e., dilute (I), semidilute (II), semi-concentrated (II') and concentrated (III) regimes. In regime II, < <r^2> > changed in proportion to <C^(-1/5)> in harmony with the scaling theory. In region II', the C dependence of < <r^2> > was explained qualitatively in terms of the Edwards theory. Similar behavior was seen in solutions of cis-PI in n-hexadecane and 1-eicosene having a marginal solvent quality.Relaxation times <tau_n> were reduced to those in an isofriction state <tau_(n zeta)> using the data for solutions of low molecular weight cis-PI. <tau_(n zeta)> in benzene and dioxane were proportional to <C^(1.3)> and <C^(1.6)> , respectively. These dependences can be explained only qualitatively by the dynamic scaling theory proposed by de Gennes. The distribution of the relaxation times was affected little by excluded volume effect and the hydrodynamic effect.