Molecular Weight Dependence of Block Copolymer Micelle Fragmentation Kinetics
Molecular Weight Dependence of Block Copolymer Micelle Fragmentation Kinetics
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DOI：
10.1021/jacs.1c02147
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发表时间：
2021-05-14
影响因子：
15
通讯作者：
Lodge, Timothy P.
中科院分区：
文献类型：
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作者：
Early, Julia T.;Block, Alison;Lodge, Timothy P.
研究了在离子液体1-乙基-3-甲基咪唑双（三氟甲基磺酰基）酰亚胺中分子量（M）对1，2-聚丁二烯-聚环氧乙烷嵌段共聚物（PB-PEO）胶束碎裂动力学的影响。一系列的六个样品，总M范围从10（4）到10（5）g mol（-1）和几乎恒定的组成（f（PEO）约为0.4），进行了检查;所有六个形成的球形胶束与PEO冠。非平衡PB-PEO胶束的制备直接溶解，系统地产生纳米粒子的平均聚集数的两倍以上的平衡值的过程。当进行高温退火（170摄氏度），平均胶束半径被发现大幅下降，由温度跳跃动态光散射（T-jump DLS）和时间分辨小角X射线散射（TR-SAXS）确定。发现特征断裂时间（tau）随着聚合度N的增加而强烈增加，因为tau类似于N-1.8。这一结果与以前未经测试的模型的预测相比是有利的。
The effect of molecular weight (M) on the fragmentation kinetics of micelles formed by 1,2-polybutadiene-block-poly(ethylene oxide) (PB-PEO) copolymers was studied in the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. A series of six samples, with total M ranging from 10(4) to 10(5) g mol(-1) and nearly constant composition (f(PEO) approximate to 0.4), were examined; all six formed spherical micelles with PEO coronas. Nonequilibrium PB-PEO micelles were prepared by direct dissolution, a process that systematically produces nanoparticles with mean aggregation numbers more than twice the equilibrium values. When subjected to high temperature annealing (170 degrees C), the average micelle radius was found to decrease substantially, as determined by temperature-jump dynamic light scattering (T-jump DLS) and time-resolved small-angle X-ray scattering (TR-SAXS). The characteristic fragmentation times (tau) were found to increase strongly with increasing degree of polymerization N, as tau similar to N-1.8. This result compares favorably with the prediction of a previously untested model.