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首页> 外文期刊>Macromolecular theory and simulations >Advanced computational strategies for modelling the evolution of full molecular weight distributions formed during multiarmed (Star) polymerisations
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Advanced computational strategies for modelling the evolution of full molecular weight distributions formed during multiarmed (Star) polymerisations

机译：用于模拟多臂（星形）聚合过程中形成的完整分子量分布演变的高级计算策略

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摘要

A novel computational strategy is described for the simulation of star polymerisations, allowing for the computation of full molecular weight distributions (MWDs). Whilst the strategy is applicable to a broad range of techniques for the synthesis of star polymers, the focus of the current study is the simulation of MWDs arising from a reversible addition fragmentation chain transfer (RAFT), R-group approach star polymerisation. In this synthetic methodology, the arms of the star grow from a central, polyfunctional moiety, which is formed initially as the refragmenting R-group of a polyfunctional RAFT agent. This synthetic methodology produces polymers with complex MWDs and the current simulation strategy is able to account for the features of such complex MWDs. The strategy involves a kinetic model which describes the reactions of a single arm of a star, the kinetics of which are implemented and simulated using the PREDICI (R) program package. The MWDs resulting from this simulation of single arms are then processed with an algorithm we describe, to generate a full MWD of stars. The algorithm is applicable to stars with an arbitrary number of arms. The kinetic model and subsequent algorithmic processing techniques are described in detail. A simulation has been parameterised using rate coefficients and densities for a 2,2'-azoisobutyronitrile (AIBN) initiated, bulk polymerisation of styrene at 60 degrees C. A number of kinetic parameters have been varied over large ranges. Conversion normalised simulations were performed, leading to information regarding star arm length, polydispersity index (PDI) and the fraction of living arms. These screening processes provided a rigorous test for the kinetic model and also insight into the conditions, which lead to optimal star formation. Finally, full MWDs are simulated for several RAFT agent/initiator ratios as well as for stars with a varying number of arms.
机译：描述了一种新颖的计算策略，用于模拟星型聚合，从而可以计算全分子量分布（MWD）。尽管该策略适用于多种合成星形聚合物的技术，但本研究的重点是模拟可逆加成断裂链转移（RAFT），R-基团星形聚合产生的MWD。在这种合成方法中，恒星臂从中央的多官能团部分生长，该部分最初形成为多官能团RAFT剂的碎片化R基团。这种合成方法可生成具有复杂MWD的聚合物，当前的模拟策略能够说明此类复杂MWD的特征。该策略涉及一个动力学模型，该模型描述了恒星单臂的反应，其动力学是使用PREDICI（R）程序包实现和模拟的。然后，通过我们描述的算法对单臂模拟产生的MWD进行处理，以生成完整的MWD星。该算法适用于具有任意臂数的恒星。详细描述了动力学模型和后续的算法处理技术。已经使用速率系数和密度对2,2'-偶氮异丁腈（AIBN）引发的苯乙烯在60摄氏度下本体聚合进行了参数化。许多动力学参数已在较大范围内变化。进行了转换归一化模拟，得出有关星臂长度，多分散指数（PDI）和活臂分数的信息。这些筛选过程为动力学模型提供了严格的测试，并洞察了导致最佳恒星形成的条件。最后，针对几种RAFT剂/引发剂比率以及具有不同臂数的恒星，模拟了完整的MWD。

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