Zhu Peng, Zhang Huapeng, Lu Hongwei
College of Textile Science and Engineering (International Institute of Silk), Zhejiang Sci-Tech University, Hangzhou 310018, China.
Polymers (Basel). 2021 May 12;13(10):1548. doi: 10.3390/polym13101548.
The droplet evaporation effect on the preparation of polyetherimide (PEI) nanoparticles by thermally induced phase separation (TIPS) was studied. PEI nanoparticles were prepared in two routes. In route I, the droplet evaporation process was carried out after TIPS. In route II, the droplet evaporation and TIPS processes were carried out simultaneously. The surface tension and shape parameters of samples were measured via a drop shape analyzer. The Z-average particle diameter of PEI nanoparticles in the PEI/dimethyl sulfoxide solution (DMSO) suspension at different time points was tested by dynamic light scattering, the data from which was used to determine the TIPS time of the PEI/DMSO solution. The natural properties of the products from both routes were studied by optical microscope, scanning electron microscope and transmission electron microscope. The results show that PEI nanoparticles prepared from route II are much smaller and more uniform than that prepared from route I. Circulation flows in the droplet evaporation were indirectly proved to suppress the growth of particles. At 30 °C, PEI solid nanoparticles with 193 nm average particle size, good uniformity, good separation and good roundness were obtained. Route I is less sensitive to temperature than route II. Samples in route I were still the accumulations of micro and nanoparticles until 40 °C instead of 30 °C in route II, although the particle size distribution was not uniform. In addition, a film structure would appear instead of particles when the evaporation temperature exceeds a certain value in both routes. This work will contribute to the preparation of polymer nanoparticles with small and uniform particle size by TIPS process from preformed polymers.
研究了液滴蒸发对热致相分离（TIPS）法制备聚醚酰亚胺（PEI）纳米粒子的影响。通过两种途径制备PEI纳米粒子。在途径I中，液滴蒸发过程在TIPS之后进行。在途径II中，液滴蒸发和TIPS过程同时进行。通过滴形分析仪测量样品的表面张力和形状参数。采用动态光散射法测试了PEI/二甲基亚砜溶液（DMSO）悬浮液中不同时间点PEI纳米粒子的Z平均粒径，并利用该数据确定PEI/DMSO溶液的TIPS时间。通过光学显微镜、扫描电子显微镜和透射电子显微镜研究了两种途径产物的自然特性。结果表明，途径II制备的PEI纳米粒子比途径I制备的纳米粒子小得多且更均匀。间接证明了液滴蒸发中的循环流动抑制了颗粒的生长。在30℃下，获得了平均粒径为193nm、均匀性好、分散性好且圆度好的PEI固体纳米粒子。途径I对温度的敏感性低于途径II。途径I中的样品在40℃时仍为微米级和纳米级颗粒的聚集体，而途径II在30℃时即已如此，尽管其粒径分布不均匀。此外，当两种途径中的蒸发温度超过一定值时，会出现膜结构而非颗粒。这项工作将有助于通过TIPS工艺从预制聚合物制备粒径小且均匀的聚合物纳米粒子。
