Departement de chimie, Centre for Self-Assembled Chemical Structures, Université de Montréal, Montréal, QC, H3C 3J7, Canada.
J Phys Chem B. 2010 Feb 25;114(7):2373-8. doi: 10.1021/jp9103867.
Electrospinning was used for the first time to prepare nanofibers of the host/guest complex between poly(ethylene oxide) (PEO) and thiourea. It is shown by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) that the stoichiometry of the complex is (EO)(12)-(thiourea)(8), settling a series of conflicting values in literature reports. The complex crystallizes in a monoclinic unit cell with a = 9.15 A, b = 18.88 A, c = 8.25 A, and beta = 92.35 degrees. On the basis of WAXD, infrared spectroscopy, and polarized Raman scattering measurements, it is proposed that the complex adopts a layered structure in which alternating PEO and thiourea layers are stabilized by intermolecular hydrogen bonds. This structure is highly reminiscent of that of the beta complex between PEO and urea. A phase diagram was determined and shows that the complex melts incongruently at 110 degrees C to form a peritectic liquid and crystals of pure thiourea. The nanofibers of the PEO-thiourea present a very large molecular orientation with a <P(2)(cos phi)>(c) value of 0.76, among the largest reported for electrospun materials.
静电纺丝首次被用于制备聚环氧乙烷（PEO）和硫脲的主客体配合物的纳米纤维。差示扫描量热法（DSC）和广角 X 射线衍射（WAXD）表明配合物的化学计量比为（EO）（12）-（硫脲）（8），解决了文献报道中一系列有冲突的数值。该配合物在单斜晶胞中结晶，晶胞参数分别为 a = 9.15 A、b = 18.88 A、c = 8.25 A 和β = 92.35 度。基于 WAXD、红外光谱和偏振拉曼散射测量，提出配合物采用层状结构，其中交替的 PEO 和硫脲层通过分子间氢键稳定。这种结构与 PEO 和尿素之间的β配合物非常相似。确定了相图，表明配合物在 110 摄氏度以非一致熔融的方式形成包晶液体和纯硫脲晶体。PEO-硫脲的纳米纤维具有非常大的分子取向，<P(2)(cos phi)>(c)值为 0.76，这是报道的电纺材料中最大的值之一。
