What happens when pesticides are solubilised in binary ionic/zwitterionic-nonionic mixed micelles?
What happens when pesticides are solubilised in binary ionic/zwitterionic-nonionic mixed micelles?
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DOI：
10.1016/j.jcis.2020.10.083
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发表时间：
2021-03-15
影响因子：
9.9
通讯作者：
Lu, Jian R.
中科院分区：
文献类型：
--
作者：
Hu, Xuzhi;Gong, Haoning;Lu, Jian R.
假设：表面活性剂已被广泛用作农用喷雾剂的佐剂，以提高农药在叶面喷雾剂沉积物中的溶解度和通过叶面角质层的流动性。以前，我们已经描述了农药在非离子表面活性剂胶束中的溶解作用，但是当农药在阴离子、阳离子和两性离子中溶解时会发生什么，以及它们与非离子表面活性剂的混合物的特性仍然很差。实验：为了便于SANS和NMR表征，我们以非离子表面活性剂六乙二醇一十二烷基醚（C12E6）、阴离子十二烷基硫酸钠（SDS）、阳离子十二烷基三甲基溴化铵（DTAB）和两性离子十二烷基磷胆碱（C12PC）作为模型助剂体系，分别溶解了具有不同结构特征的三种农药，分别是嘧菌酯（CP）、偶氮菌酯（AZ）和二苯唑唑（DF）。研究的重点是在没有或存在电解质的情况下，增溶物对驱动胶束纳米结构变化的影响。利用NMR和noesi研究了各农药在胶束中的溶解度和位置。SANS被用来揭示由于有和没有电解质的农药溶解而引起的胶束结构的细微变化。发现：与非离子表面活性剂不同，离子和两性离子表面活性剂的胶束结构在农药溶解后保持不变。电解质略微拉长了离子表面活性剂的胶束，但对非离子和两性离子表面活性剂没有影响。农药的增溶可以改变离子/两性离子和离子/非离子胶束二元混合物的结构，引起胶束的伸长、壳收缩和脱水，确切的改变由混合物中的摩尔比决定。(C) 2020由爱思唯尔公司出版。
Hypothesis: Surfactants have been widely used as adjuvants in agri-sprays to enhance the solubility of pesticides in foliar spray deposits and their mobility through leaf cuticles. Previously, we have characterised pesticide solubilisation in nonionic surfactant micelles, but what happens when pesticides become solubilised in anionic, cationic and zwitterionic and their mixtures with nonionic surfactants remain poorly characterised.Experiments: To facilitate characterisations by SANS and NMR, we used nonionic surfactant hexaethylene glycol monododecyl ether (C12E6), anionic sodium dodecylsulphate (SDS), cationic dodecyltrimethylammonium bromide (DTAB) and zwitterionic dodecylphosphocholine (C12PC) as model adjuvant systems to solubilise 3 pesticides, Cyprodinil (CP), Azoxystrobin (AZ) and Difenoconazole (DF), representing different structural features. The investigation focused on the influence of solubilisates in driving changes to the micellar nanostructures in the absence or presence of electrolytes. NMR and NOESY were applied to investigate the solubility and location of each pesticide in the micelles. SANS was used to reveal subtle changes to the micellar structures due to pesticide solubilisation with and without electrolytes.Findings: Unlike nonionic surfactants, the ionic and zwitterionic surfactant micellar structures remain unchanged upon pesticide solubilisation. Electrolytes slightly elongate the ionic surfactant micelles but have no effect on nonionic and zwitterionic surfactants. Pesticide solubilisation could alter the structures of the binary mixtures of ionic/zwitterionic and ionic/nonionic micelles by causing elongation, shell shrinkage and dehydration, with the exact alteration being determined by the molar ratio in the mixture. (C) 2020 Published by Elsevier Inc.