Abstract In this study, poly(N-vinyl pyrrolidone) (PVP), a cheap, safe and non-toxic polymer, was explored using a range of analytical methods including fluorescence microscopy to gain insight into the role of polymer physicochemical properties on rainfastness, i.e. tenacity of foliar deposits against rain, of agrochemicals on plant surfaces. Three methods were approached to increase rainfastness of PVP, i.e. using high molecular weight grades of the polymer, pre- blending PVP with poly(acrylic acid) (PAA) and successively depositing drops of each polymer (PVP or PAA) on top of the other. Regarding the first method, from the different commercial grades of PVP studied, it was revealed that the polymer with highest molecular weight (1300 kDa) significantly improved the rainfastness of a model fungicide (azoxystrobin). The rainfastness results correlated with film dissolution in water. In the second method, rainfastness properties of PVP were improved by mixing it with PAA and it was shown that PVP-PAA mixtures at the 50:50 wt ratio retarded film dissolution by a factor of 2–3 compared to the PVP alone. In the third method, a novel approach was employed by placing drops of PAA solution on PVP drops on paraffin film and leaving to physically mix and dry down. In this proof-of-concept study, the washing-off profiles of the dry deposits revealed a striking rainfastness increase almost to the level of the insoluble controls. Methods employed in this study to increase rainfastness of agrochemical formulations can explain the previously reported effects of water-soluble polymers on rainfastness and allows the identification of improved rainfastness aids.

中文翻译：

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基于 N-乙烯基吡咯烷酮聚合物及其与聚（丙烯酸）的互聚物复合物的农化配方的耐雨性

摘要 在这项研究中，使用包括荧光显微镜在内的一系列分析方法探索了聚（N-乙烯基吡咯烷酮）（PVP），一种廉价、安全和无毒的聚合物，以深入了解聚合物理化性质对耐雨性的作用，即叶面沉积物抵抗雨水、植物表面农用化学品的坚韧。尝试了三种方法来提高 PVP 的耐雨性，即使用高分子量等级的聚合物，将 PVP 与聚（丙烯酸）（PAA）预混，然后将每种聚合物（PVP 或 PAA）的液滴依次沉积在另一个之上. 关于第一种方法，从研究的不同商业等级的 PVP 中发现，具有最高分子量 (1300 kDa) 的聚合物显着提高了模型杀菌剂（嘧菌酯）的耐雨性。耐雨性结果与薄膜在水中的溶解度相关。在第二种方法中，通过将 PVP 与 PAA 混合来改善 PVP 的耐雨性能，结果表明，与单独使用 PVP 相比，重量比为 50:50 的 PVP-PAA 混合物延迟了 2-3 倍的薄膜溶解。在第三种方法中，采用了一种新颖的方法，将 PAA 溶液滴放在石蜡膜上的 PVP 滴上，然后物理混合并干燥。在这项概念验证研究中，干燥沉积物的冲刷曲线显示耐雨性显着增加，几乎达到不溶性对照物的水平。本研究中使用的提高农化配方耐雨性的方法可以解释先前报道的水溶性聚合物对耐雨性的影响，并允许鉴定改进的耐雨性助剂。