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Poor Solvents Improve Yield of Grafting-Through Radical Polymerization of OEO19MA
ACS Macro Letters ( IF 5.8 ) Pub Date : 2020-04-24 , DOI: 10.1021/acsmacrolett.0c00245
Michael R Martinez 1 , Pawel Krys 1 , Sergei S Sheiko 2 , Krzysztof Matyjaszewski 1
Affiliation  

Radical polymerization of poly(ethylene glycol) methyl ether methacrylate (OEO19MA, Mn ∼ 950) at an initial monomer concentration of 150 mM was investigated as a function of solvent composition. Conventional and controlled radical polymerizations in anisole at 60 °C converged at approximately the same equilibrium monomer concentration ([M]eq) of ∼38 mM, suggesting that livingness or diminished termination did not affect the thermodynamic parameters of polymerization. Conventional radical polymerizations (RPs) in anisole, dimethylformamide (DMF), toluene, and 1×PBS buffered water were taken to approximately 98% thermal initiator decomposition to determine [M]eq at reaction completion within a broad temperature range. The enthalpy (ΔHp) and entropy (ΔSp°) of polymerization were solvent-dependent. Polymerizations in 1×PBS were the most thermodynamically favorable, followed by those in DMF, toluene, and anisole. −ΔHp and −ΔSp increased with the square of the difference in the Hansen solubility parameters of poly(ethylene glycol) and the solvent. It is proposed that poor solvents favor polymer–polymer interactions over polymer–solvent interactions, which improves the thermodynamic polymerizability.

中文翻译:

不良溶剂通过OEO19MA的自由基聚合提高接枝率

研究了初始单体浓度为 150 mM 的聚(乙二醇)甲基醚甲基丙烯酸酯(OEO 19 MA,Mn ∼ 950)的自由基聚合与溶剂组成关系苯甲醚中的常规和受控自由基聚合在 60 °C 下收敛于大约相同的平衡单体浓度 ([M] eq ) 约 38 mM,这表明活性或终止减少不会影响聚合的热力学参数。在苯甲醚、二甲基甲酰胺 (DMF)、甲苯和 1×PBS 缓冲水中进行常规自由基聚合 (RPs),热引发剂分解率约为 98%,以确定 [M] eq在较宽的温度范围内完成反应。聚合的焓 (Δ H p ) 和熵 (Δ S p ° ) 与溶剂有关。1×PBS 中的聚合在热力学上最有利,其次是 DMF、甲苯和苯甲醚。-Δ H p和 -Δ S p随着聚(乙二醇)和溶剂的汉森溶解度参数差异的平方而增加。有人提出,不良溶剂有利于聚合物-聚合物相互作用而不是聚合物-溶剂相互作用,这提高了热力学聚合性。
更新日期:2020-04-24
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