Dielectric normal mode spectroscopy in the ordered and disordered states of diblock copolymers
Dielectric normal mode spectroscopy in the ordered and disordered states of diblock copolymers
复制标题
二嵌段共聚物有序和无序状态下的介电简正模光谱
DOI：
10.1021/ma00046a031
复制
发表时间：
1992
期刊：
影响因子：
5.5
通讯作者：
F. Stickel
中科院分区：
文献类型：
--
作者：
B. Stühn;F. Stickel
使用小角 X 射线散射 (SAXS) 和介电光谱研究了一系列低分子量 (10500-20800) 和各种成分的聚苯乙烯/顺式 1,4-异戊二烯二嵌段共聚物中的微相分离转变 (MST)。研究了从有序状态到无序状态的完整政权。两种方法的结合使得将动力学与结构特性联系起来成为可能。 SAXS 确定了一个广泛的过渡区域，其特征是在缺乏长程有序的情况下存在强烈的浓度波动。研究表明，这些聚合物在实验可达到的温度下会经历 MST。将二嵌段共聚物中聚异戊二烯常态模式的介电谱与均聚物情况进行比较。它用于研究聚异戊二烯嵌段体积中有效成分的温度依赖性。有序状态由分离良好的聚异戊二烯状态组成。然而，由于与聚苯乙烯的偶联，相对于均聚物情况，弛豫时间谱显着拓宽。从有序到无序的转变不会导致两个块的均匀混合。自由体积模型描述了简正模式弛豫时间的完整温度依赖性。
The microphase separation transition (MST) in a series of diblock copolymers of polystyrene/cis-1,4-isoprene of low molecular weight (10500-20800) and various compositions is studied using small-angle X-ray scattering (SAXS) and dielectric spectroscopy. The full regime from the ordered to the disordered state is investigated. The combination of both methods makes it possible to relate dynamical to structural properties. SAXS identifies a broad transition regime which is characterized by strong concentration fluctuations in the absence of long-range order. The polymers are shown to go through their MST at experimentally accessible temperatures. Dielectric spectroscopy of the polyisoprene normal mode in the diblock copolymers is compared to the homopolymer case. It is used to study the temperature dependence of the effective composition in the volume of the polyisoprene block. The ordered state consists of well-separated polyisoprene regimes. However, the relaxation time spectrum is considerably broadened with respect to the homopolymer case due to the coupling to polystyrene. The order-to-disorder transition does not lead to a homogeneous mixing of both blocks. The full temperature dependence of the normal mode relaxation time is described in a free volume model.