Polymerization of methyl acrylate mediated by copper(0)/Me6‐TREN in hydrophobic media enhanced by phenols; Single electron transfer‐living radical polymerization
Polymerization of methyl acrylate mediated by copper(0)/Me6‐TREN in hydrophobic media enhanced by phenols; Single electron transfer‐living radical polymerization
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DOI：
10.1002/pola.23042
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发表时间：
2008-11
期刊：
影响因子：
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通讯作者：
P. Wright;G. Mantovani;D. Haddleton
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文献类型：
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作者：
P. Wright;G. Mantovani;D. Haddleton
采用苯酚作为添加剂，提高了常温下甲苯中SET-LRP的收率。反应时间与苯酚的添加量有直接关系，引发剂的最佳添加量为20等量苯酚。丙烯酸甲酯（MA）的聚合是在不同数量的苯酚存在下进行的，聚合速率取决于苯酚相对于引发剂的浓度。在超过20倍的情况下，218分钟后转化率为93% (PDI = 1.06, M-n = 11500 g mol(-1))，而在超过5倍的情况下转化率为80% （PDI = 1.21, M-n = 5310 g mol(-1)）。当非位阻苯酚相对于引发剂过量20摩尔时，聚合反应具有良好的线性一级动力学，并得到PDI在1.06至1.16之间的聚合物。当使用高度受阻的苯酚时，在聚合发生之前有一个明显的诱导期，这与不使用苯酚时类似。与未添加苯酚的聚合相比，较少阻碍的苯酚加速了聚合。羟基上空间位阻的增加阻止了这种配位，这表明苯酚与铜(0)或铜(I)的作用不同。脂肪族和芳族酯和酰胺被成功地用作引发剂，得到了M-n接近预测值的聚合物，近似于10,000 g mol(-1)， PDI通常小于1.10。在大多数情况下观察到一个诱导期，它可以在添加单体之前通过预平衡步骤去除。这导致在甲苯溶液（50 vol %）中观察到优异的一级动力学。将Cu(0)（粉末）/Me-6-TREN与20等量的苯酚和除单体外的所有反应物加入反应烧瓶中，在25℃下搅拌45 min。MALDI TOF MS显示，聚合物的结构包含烷基溴引发剂衍生的溴链末端。这个端基的保留与活性自由基聚合一致。(C) 2008 Wiley期刊有限公司高分子科学A辑：高分子。化学46 (6):776 - 785,2008
Phenol has been used as an additive to enhance the rate of SET-LRP in toluene at ambient temperature. A direct relationship between reaction time and amount of phenol added has been found with the optimum amount being similar to 20 equiv. of phenol with respect to initiator. Polymerization of methyl acrylate (MA) has been carried out in the presence of varying amounts of phenol and the rate of polymerization depends on the concentration of phenol relative to initiator. With a 20-fold excess 93% conversion is observed after 218 min (PDI = 1.06, M-n = 11,500 g mol(-1)) when compared with 80% conversion with a 5-fold excess (PDI = 1.21, M-n = 5310 g mol(-1)). When nonsterically hindered phenols are employed in a 20 molar excess with respect to the initiator the polymerizations have good linear first-order kinetics and give polymers with PDI between 1.06 and 1.16. When a highly hindered phenol is employed there is a significant induction period prior to polymerization taking place which is similar to when using no phenol. Less hindered phenols accelerated the polymerization when compared with polymerizations with no added phenol. Increasing steric hindrance at the -OH prevents this coordination which indicates that the role of phenol is different with either copper(0) or copper(I). Aliphatic and aromatic esters and amides were used successfully as initiators giving polymers with M-n close to that predicted at similar to 10,000 g mol(-1) and PDI typically less than 1.10. An induction period is observed in most cases which can be removed by a pre-equilibrium step before the addition of monomer. This results in excellent first-order kinetics being observed in the polymerization of MA in toluene solution (50 vol %). Here Cu(0) (powder)/Me-6-TREN with 20 equiv. of phenol and all of the reactants, except the monomer, were added to the reaction flask and stirred for 45 min at 25 degrees C. The structure of the polymer is shown by MALDI TOF MS to contain bromide chain ends derived from the alkyl bromide initiator. The retention of this end group is consistent with living radical polymerization. (C) 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym. Chem 46: 7376-7385, 2008