Segmental motion in poly(styrene‐b‐1,4‐isoprene) block copolymers in the disordered state
Segmental motion in poly(styrene‐b‐1,4‐isoprene) block copolymers in the disordered state
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无序状态下聚(苯乙烯-b-1,4-异戊二烯)嵌段共聚物的链段运动
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发表时间：
1992
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影响因子：
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通讯作者：
J. Roovers
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作者：
A. Rizos;G. Fytas;J. Roovers
通过光子相关光谱研究了与有序-无序转变（ODT）接近程度不同的三种聚（苯乙烯-b-1,4-异戊二烯）二嵌段共聚物中两个初级松弛过程相关的链段动力学。利用去偏振光散射的选择性，通过 ODT 附近但上方的相同实验技术明确揭示了两种不同取向过程的存在。这些主要 α 弛豫模式是由无序嵌段共聚物中的组成场配置（“模式”）产生的，相关长度 xic 大于玻璃化转变温度 Tg 附近 α 弛豫的协同尺寸 xiα。缓慢波动的组成模式的存在可能导致观察到松弛函数 L(log τ) 的分段分布过度加宽，超出本体均聚物的分布。对于缓慢的 α 过程，分配给富含聚苯乙烯的微区域内的片段取向，一个新的发现是温度依赖性......
The segmental dynamics associated with two primary relaxation processes in three poly(styrene‐b‐1,4‐isoprene) diblock copolymers with different proximity to the order–disorder transition (ODT) were investigated by photon correlation spectroscopy. Utilizing the selectivity of the depolarized light scattering, the presence of two distinct orientational processes were unambiguously revealed by the same experimental technique near but above ODT. These primary α‐relaxation modes result from the composition field configuration (‘‘pattern’’) in disordered block copolymers with correlation length ξc larger than the cooperative size ξα of the α relaxation near the glass transition Tg. The existence of a slowly fluctuating composition pattern can lead to the observed excess broadening of the segmental distribution of relaxation function L(log τ) beyond that of bulk homopolymers. For the slow α process, assigned to segmental orientation within microregions rich in polystyrene, a new finding is the temperature depend...