Maneuvering the internal porosity and surface morphology of electrospun polystyrene yarns by controlling the solvent and relative humidity.
Maneuvering the internal porosity and surface morphology of electrospun polystyrene yarns by controlling the solvent and relative humidity.
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DOI：
10.1021/la400747y
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发表时间：
2013-06-11
期刊：
影响因子：
--
通讯作者：
Xia Y
中科院分区：
文献类型：
--
作者：
Lu P;Xia Y
本文提出了一种简单可靠的方法，利用适当的溶剂和相对湿度的组合来生产由纳米原纤束组成的聚苯乙烯(PS)纱线。我们通过系统地研究了聚合物、溶剂(S)和水蒸气之间的分子相互作用，阐明了这种新形态形成的机理。我们证明了蒸汽诱导的相分离在生成具有独特结构的纱线中起着关键作用。此外，我们还发现，N，N-二甲基甲酰胺(DMF)的低蒸汽压对内部气孔的演化至关重要。相反，四氢呋喃(THF)相对较高的蒸汽压阻碍了内部气孔的形成，但有利于形成粗糙的表面。在所有情况下，我们的结果都清楚地表明，内部孔隙率或表面粗糙度的形成需要在适当的相对湿度水平下存在水蒸气，这是聚合物的一种非溶剂。准确的形貌或孔结构取决于溶剂(S)(DMF、THF及其混合物)的蒸发速度，以及非溶剂(水)和溶剂(S)的相互扩散和渗透。我们的发现可以作为通过电纺丝在内部和外部制备具有所需孔隙率的纤维的指导方针。
This article presents a simple and reliable method for generating polystyrene (PS) yarns composed of bundles of nanofibrils by using a proper combination of solvent and relative humidity. We elucidated the mechanism responsible for the formation of this new morphology by systematically investigating the molecular interactions among the polymer, solvent(s), and water vapor. We demonstrated that vapor-induced phase separation played a pivotal role in generating the yarns with a unique structure. Furthermore, we discovered that the low vapor pressure of N,N-dimethylformamide (DMF) was critical to the evolution of pores in the interiors. On the contrary, the relatively high vapor pressure of tetrahydrofuran (THF) hindered the formation of interior pores but excelled in creating a rough surface. In all cases, our results clearly indicate that the formation of either internal porosity or surface roughness required the presence of water vapor, a nonsolvent of the polymer, at a proper level of relative humidity. The exact morphology or pore structure was dependent on the speed of evaporation for the solvent(s) (DMF, THF, and their mixtures), as well as the inter-diffusion and penetration of the nonsolvent (water) and solvent(s). Our findings can serve as guidelines for the preparation of fibers with desired porosity both internally and externally through electrospinning.
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