ROY Crystallization on Poly(ethylene) Fibers, a Model for Bed Net Crystallography
ROY Crystallization on Poly(ethylene) Fibers, a Model for Bed Net Crystallography
复制标题
DOI：
10.1021/acs.chemmater.3c03188
复制
发表时间：
2024-02-27
影响因子：
8.6
通讯作者：
Kahr，Bart
中科院分区：
文献类型：
--
作者：
Erriah，Bryan;Shtukenberg，Alexander G.;Kahr，Bart
许多用于防止疾病媒介的长效杀虫蚊帐由聚乙烯纤维组成，在制造过程中将杀虫剂掺入其中。杀虫剂分子从过饱和聚合物内部扩散到表面，在那里它们变得可供昆虫生物利用，并且通常会结晶，这一过程称为“开花”。最近的研究表明，接触性杀虫剂可能具有高度多晶型性。此外，杀虫活性取决于多晶型，具有较高晶体自由能的形式可以更快地击倒昆虫并导致死亡。因此，纤维上形成的杀虫剂晶体的晶体学表征对于了解网络功能和改善网络性能至关重要。然而，由于晶体尺寸微小，床网纤维表面上的杀虫剂晶体的结构特征一直难以捉摸，更不用说它们的多晶型物了。使用高度多晶型化合物 ROY（5-甲基-2-[(2-硝基苯基）-氨基]噻吩-3-甲腈）作为杀虫剂结晶的代表，我们研究了含有 ROY 的挤出聚乙烯纤维表面的起霜和晶体形成。从挤出时开始跟踪的喷霜率在连续洗涤后通过紫外可见光谱测定。在聚乙烯纤维表面观察到了 6 种结晶多晶型物（已知的 13 种），并通过拉曼显微镜、扫描电子显微镜和 3D 电子衍射对它们进行了鉴定和表征。这些观察结果表明，聚乙烯纤维上形成的多晶型物的结晶和相行为是复杂且动态的。起霜和微晶的表征强调了床网晶体学对于优化床网性能的重要性。
Many long-lasting insecticidal bed nets for protection against disease vectors consist of poly(ethylene) fibers in which insecticide is incorporated during manufacture. Insecticide molecules diffuse from within the supersaturated polymers to surfaces where they become bioavailable to insects and often crystallize, a process known as blooming. Recent studies revealed that contact insecticides can be highly polymorphic. Moreover, insecticidal activity is polymorph-dependent, with forms having a higher crystal free energy yielding faster insect knockdown and mortality. Consequently, the crystallographic characterization of insecticide crystals that form on fibers is critical to understanding net function and improving net performance. Structural characterization of insecticide crystals on bed net fiber surfaces, let alone their polymorphs, has been elusive owing to the minute size of the crystals, however. Using the highly polymorphous compound ROY (5-methyl-2-[(2-nitrophenyl)-amino]thiophene-3-carbonitrile) as a proxy for insecticide crystallization, we investigated blooming and crystal formation on the surface of extruded poly(ethylene) fibers containing ROY. The blooming rates, tracked from the time of extrusion, were determined by UV–vis spectroscopy after successive washes. Six crystalline polymorphs (of the 13 known) were observed on poly(ethylene) fiber surfaces, and they were identified and characterized by Raman microscopy, scanning electron microscopy, and 3D electron diffraction. These observations reveal that the crystallization and phase behavior of polymorphs forming on poly(ethylene) fibers is complex and dynamic. The characterization of blooming and microcrystals underscores the importance of bed net crystallography for the optimization of bed net performance.