Rheology and Structure of Entangled Telechelic Linear and Star Polyisoprene Melts
Rheology and Structure of Entangled Telechelic Linear and Star Polyisoprene Melts
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DOI：
10.1021/ma902769s
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发表时间：
2010-04
期刊：
影响因子：
5.5
通讯作者：
E. Ruymbeke;D. Vlassopoulos;M. Mierzwa;T. Pakuła;D. Charalabidis;M. Pitsikalis;N. Hadjichristidis
中科院分区：
文献类型：
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作者：
E. Ruymbeke;D. Vlassopoulos;M. Mierzwa;T. Pakuła;D. Charalabidis;M. Pitsikalis;N. Hadjichristidis
我们研究了具有不同摩尔质量的遥螺旋线和星形(不同官能度)聚异戊二烯熔体的线性粘弹性响应与其结构的关系。我们发现，这些系统由于强烈的偶极相互作用而自我组装，形成的星团似乎主要取决于每颗恒星的偶极群的数量。动力学相当复杂，但观察到了一些相关的特征：链段动力学受到遥控官能化的影响，特别是对短臂长的官能化；这反映了微观结构(从而玻璃化转变温度)随着官能化的变化。与类似的非离子恒星相比，末态弛豫慢得多，反映了星团的弛豫。线型半螺旋聚合物(只有一端官能化)以星形方式聚集。我们进一步发展了一种基于时间推进算法的星体和线链的管状模型，其中我们通过每个时间步的偶极相互作用来结合缔合状态或链。使用两个可调参数(两个偶极对分别保持结合或自由的平均时间)，预测与数据的一致性是显著的，并为形成所需的超分子组装提出了设计标准。
We investigate the linear viscoelastic response of model telechelic linear and star (of varying functionality) polyisoprene melts with different molar masses above the entanglement limit in relation to their structure. We find that these systems self-assemble as a result of the strong dipolar interactions and form clusters that seem to depend primarily on the number of dipolar groups per star. The dynamics is rather complex, but some pertinent features are observed: the segmental dynamics is affected by the telechelic functionalization, especially for short arm lengths; this reflects the change of microstructure (and thus glass-transition temperature) with functionalization. The terminal relaxation is much slower compared to similar nonionic stars, reflecting the relaxation of clusters. Linear semitelechelic polymers (with only one end functionalized) aggregate in a star-like fashion. We further develop a tube model based on the time-marching algorithm for stars and linear chains, where we incorporate the association status or the chains via the dipolar interactions at each time step. The agreement of the predictions with the data, using two adjustable parameters (the average times when two dipolar pair remain associated or free, respectively), is remarkable and suggests design criteria for forming desired supramolecular assemblies.