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水相静电纺丝聚异丙基丙烯酰胺环境参数的控制
ACS Appl. Mater. Interfaces2017, 9, 24100−24110 像PNIPAM的热敏型高分子，是理想的水相纺丝材料，因为，低临界共融温度的行为使水相静电纺丝在低于低临界共融温度时能够实现，并且在高于低临界共溶温度时在应用过程中具有水稳定性。然而，低临界共溶温度对水相静电纺丝的影响很少被研究，即使考虑到研究也并不深入。之前的文献报道，PNIPAM在水相中可纺性差，需要结合像是丙酮或DMF, THF 之类的有机溶剂增加它的可纺性，再或者可能与其他高分子共同纺丝。然而需要注意的是，目前还没有研究利用LCST行为增加PNIPAM的可纺性。室内参数如环境温度，相对湿度也没有被充分考虑。然而，调整这些工艺参数，对研究像是PNIPAM这类温敏型高分子的加工性能是至关重要的。 比利时根特大学的EllaSchoolaert透彻的研究了环境温度以及相对湿度的影响。充分利PNIPAM的热敏行为增加PNIPAM的可纺性。通常认为，稳定的静电纺丝过程需要适宜的粘度，良好的溶解性，通过流变行为和比浊法测试研究温度的控制，此外采用详细的动态蒸汽吸附分析（DVS）确定最佳的相对湿度。 Thermoresponsive polymers, such as Poly(N‑isopropylacrylamide) (PNIPAM), are appealing materials for waterborne electrospinning as their LCST-behavior enables nanofiber production from water below the LCST transition yet provides water stability during application above the LCST transition. However, this option has barely been investigated, and if considered, it has met with only limited success. Previous studies report very poor PNIPAM electrospinnability from water and required a combined, harsher solvent system, e.g. acetone or toxic solvents such as DMF and THF or the use of copolymers where another polymer is introduced in order to facilitate the electrospinning process. It should, however, be highlighted that, to the best of our knowledge, none of these studies have fully exploited the LCST behavior to enhance the electrospinnability of PNIPAM. In general, ambient parameters such as the environmental temperature and relative humidity have not been considered. However, it can be expected that tuning of these parameters will be crucial for the processability of a thermoresponsive polymer such as PNIPAM. Therefore, in the present work, the influence of both the environmental temperature and relative humidity is studied thoroughly by Ella Schoolaert, hereby fully exploiting the thermoresponsive behavior of PNIPAM to enhance electrospinnability from water. Based on the common insight that a certain viscosity and good solubility are required for a stable electrospinning process, systematic rheological analysis and turbidimetry measurements are employed to study the effect of temperature control. Additionally, the identification of the optimal relative humidity is facilitated and supported by detailed dynamic vapor sorption (DVS) analysis. （高大千）
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