Strong Variation of Micelle-Unimer Coexistence as a Function of Core Chain Mobility.
Strong Variation of Micelle-Unimer Coexistence as a Function of Core Chain Mobility.
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DOI：
10.1021/acs.macromol.1c00635
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发表时间：
2021-07
期刊：
影响因子：
5.5
通讯作者：
Ryan J Carrazzone;Xiuli Li;Jeffrey C. Foster;V. Uppala;Candace E. Wall;A. Esker;L. Madsen;John B. Matson
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文献类型：
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作者：
Ryan J Carrazzone;Xiuli Li;Jeffrey C. Foster;V. Uppala;Candace E. Wall;A. Esker;L. Madsen;John B. Matson
聚合物胶束在溶液中与未组装的链共存。我们研究了胶束成核块的玻璃化转变温度（tg）（即链迁移率）对胶束-单体共存的影响。我们合成了7个分子量相近（12 kg/mol）的PEG-b- p （nBA- an-tBA）两亲嵌段共聚物（PEG =聚乙二醇，nBA =丙烯酸正丁酯，tBA =丙烯酸叔丁酯）。改变nBA/tBA的摩尔比，可以在岩心疏水性和胶束大小没有显著变化的情况下，实现岩心块T g的宽调制。核磁共振扩散测量显示，当核心区块温度从25°C降低到-46°C时，一元聚体占聚合物总浓度的比例从0%增加到54%。此外，在固定的聚合物组成下，unimer的居群（以及核心温度）随着温度的升高而增加。该研究证明了核形成块迁移率对聚合物自组装的强烈影响，为设计药物输送系统提供了信息，并提出了新的动力学理论的必要性。
Polymeric micelles coexist in solution with unassembled chains (unimers). We have investigated the influence of glass transition temperature (T g) (i.e., chain mobility) of the micelle core-forming blocks on micelle-unimer coexistence. We synthesized a series of seven PEG-b-P(nBA-ran-tBA) amphiphilic block copolymers (PEG = poly(ethylene glycol), nBA = n-butyl acrylate, tBA = tert-butyl acrylate) with similar molecular weights (12 kg/mol). Varying the nBA/tBA molar ratio enabled broad modulation of core block T g with no significant change in core hydrophobicity or micelle size. NMR diffusometry revealed increasing unimer populations from 0% to 54% of total polymer concentration upon decreasing core block T g from 25 to -46 °C. Additionally, unimer population at fixed polymer composition (and thus core T g) increased with temperature. This study demonstrates the strong influence of core-forming block mobility on polymer self-assembly, providing information toward designing drug delivery systems and suggesting the need for new dynamical theory.