Poor Solvents Improve Yield of Grafting-Through Radical Polymerization of OEO 19 MA
Poor Solvents Improve Yield of Grafting-Through Radical Polymerization of OEO 19 MA
复制标题
不良溶剂提高了 OEO 19 MA 自由基聚合接枝的产率
DOI：
10.1021/acsmacrolett.0c00245
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发表时间：
2020
影响因子：
7.015
通讯作者：
Matyjaszewski, Krzysztof
中科院分区：
文献类型：
--
作者：
Martinez, Michael R.;Krys, Pawel;Sheiko, Sergei S.;Matyjaszewski, Krzysztof
自由基聚合的聚（乙二醇）甲基醚甲基丙烯酸酯（OEO 19 MA，Mn ≥ 950）在初始单体浓度为150 mM的溶剂组合物的函数进行了研究。在苯甲醚中在60 °C下的常规和受控自由基聚合在大约相同的平衡单体浓度（[M]eq）下收敛于约38 mM，这表明活性或减少的终止不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（RP），使约98%的热引发剂分解，以确定在宽温度范围内的[M]eqat反应完成。聚合反应的焓（ΔHp）和熵（ΔSp°）与溶剂有关。在1×PBS中的聚合是最有利的，其次是在DMF，甲苯和苯甲醚中的聚合。- Δ Hp和-Δ Sp随聚乙二醇和溶剂的汉森溶解度参数之差的平方而增加。研究表明，相对于聚合物-溶剂相互作用，差溶剂更有利于聚合物-聚合物相互作用，从而提高了热力学聚合能力。
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]eqat 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. −ΔHpand −ΔSpincreased 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.