Time-Domain NMR Observation of Entangled Polymer Dynamics: Focus on All Tube-Model Regimes, Chain Center, and Matrix Effects
Time-Domain NMR Observation of Entangled Polymer Dynamics: Focus on All Tube-Model Regimes, Chain Center, and Matrix Effects
复制标题
DOI：
10.1021/acs.macromol.8b00443
复制
发表时间：
2018-05
期刊：
影响因子：
5.5
通讯作者：
Marie-Luise Trutschel;A. Mordvinkin;F. Furtado;L. Willner;K. Saalwächter
中科院分区：
文献类型：
--
作者：
Marie-Luise Trutschel;A. Mordvinkin;F. Furtado;L. Willner;K. Saalwächter
结合时温叠加的质子多量子时域核磁共振技术是研究纠缠链动力学的有力手段。克服了以前的限制，制度II-IV的管模型，本研究扩展的方法，制度I（本地化劳斯运动）通过使用脉冲序列适应较短的时间，从而涵盖了所有相关的制度的聚（丁二烯）与分子量（M）在10和200 kDa之间的模型情况。我们确定的纠缠时间是一致的，与当前的流变学结果的值，并确认低于1的值的时间标度指数的分段取向自相关函数（OACF）在制度我以前观察到的其他NMR技术。偏离管模型预测的起源进行评估，通过专注于链中心的动力学在端链氘代三嵌段样品和稀释的探针链到15%的氘代矩阵与M的2 MDa。该研究补充了自扩散系数。
Proton multiple-quantum time-domain NMR combined with time–temperature superposition is a powerful method to study entangled chain dynamics. Overcoming the previous limitation to regimes II–IV of the tube model, this study extends the method to regime I (localized Rouse motions) by use of a pulse sequence adapted to shorter times, thus covering all relevant regimes for the model case of poly(butadiene) with molecular weights (M) between 10 and 200 kDa. We determine a value for the entanglement time that is consistent with current rheological results and confirm a value below 1 for the time scaling exponent of the segmental orientation autocorrelation function (OACF) in regime I previously observed by other NMR techniques. The origins of deviations from tube-model predictions are assessed by focusing on the dynamics of the chain centers in end-chain deuterated triblock samples and by dilution of probe chains to 15% in a deuterated matrix with M of 2 MDa. The study is complemented by self-diffusion coeffici...