Interaction between pentaethylene glycol n-octyl ether and poly(acrylic acid): effect of the polymer molecular weight.
Interaction between pentaethylene glycol n-octyl ether and poly(acrylic acid): effect of the polymer molecular weight.
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五乙二醇正辛基醚与聚丙烯酸之间的相互作用：聚合物分子量的影响。
DOI：
10.1016/j.jcis.2007.05.035
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发表时间：
2007
影响因子：
9.9
通讯作者：
R. Sartorio
中科院分区：
文献类型：
--
作者：
G. D’Errico;D. Ciccarelli;O. Ortona;L. Paduano;R. Sartorio
通过张力测定、电位测定、量热测定、荧光猝灭和内部扩散（脉冲梯度自旋回波核磁共振）测量等组合实验策略，研究了聚合物分子量对五甘醇正辛基醚（C8E5）和聚丙烯酸（PAA）之间相互作用的影响。考虑了平均分子量在较宽范围内变化（M w = 2000、100,000、250,000 和 450,000）的 PAA 样品。测量是在恒定的聚合物浓度（0.1% w/w）和不同的表面活性剂摩尔浓度下进行的。在所有考虑的系统中，在低表面活性剂浓度下，已检测到表面活性剂单体吸附到聚合物链上。在独立于 PAA M w 的 C8E5 摩尔浓度 (T1) 下，表面活性剂分子开始聚集，形成聚合物共同参与的簇。高于此浓度，系统的行为取决于 Mwtw。事实上，如果使用高分子量（Mwt⩾100,000）的聚合物样品，所有添加的表面活性剂都会聚集到聚合物上，导致聚合物饱和，随后形成自由胶束。饱和和游离胶束化均在与聚合物分子量无关的表面活性剂浓度下发生。含有低分子量（Mwt=2000）PAA的C8E5水性混合物表现不同，因为在T1以上，只有一小部分（~20%）添加的表面活性剂分子与聚合物相互作用，形成多个PAA链参与的聚集体。在这种情况下，C8E5游离胶束化发生在聚合物饱和之前。实验证据已根据驱动表面活性剂-聚合物聚集的各种分子相互作用之间的微妙平衡进行了解释。
The effect of the polymer molecular weight on the interaction between pentaethylene glycol n-octyl ether (C8E5) and poly(acrylic acid) (PAA) has been investigated by a combined experimental strategy including tensiometry, potentiometry, calorimetry, fluorescence quenching and intradiffusion (pulsed gradient spin echo-NMR) measurements. PAA samples with an average molecular weight varying in a wide range (M¯w=2000, 100,000, 250,000, and 450,000) have been considered. The measurements have been performed at constant polymer concentration (0.1% w/w) with varying surfactant molality. In all the considered systems, at low surfactant concentration, adsorption of surfactant monomers onto the polymer chain has been detected. At a C8E5molality (T1) independent of the PAA M¯w, surfactant molecules start to aggregate, forming clusters to which the polymer co-participates. Above this concentration, the behavior of the system depends on M¯w. In fact, if polymer samples with high molecular weight (M¯w⩾100,000) are employed, all the added surfactant aggregates onto the polymer leading to the polymer saturation and, subsequently, to free micelles formation. Both saturation and free micellization occur at surfactant concentrations which are independent of the polymer molecular weight. C8E5aqueous mixtures containing PAA with low molecular weight (M¯w=2000) behaves differently, in that, above T1, only a fraction (∼20%) of the added surfactant molecules interact with the polymer, forming aggregates to which more than one PAA chain participate. In this case, C8E5free micellization occurs before polymer saturation. The experimental evidences have been interpreted in terms of the subtle balance between the various molecular interactions driving the surfactant–polymer aggregation.