Impact of Ionic Liquid-Modified Multiwalled Carbon Nanotubes on the Crystallization Behavior of Poly(vinylidene fluoride)

详细信息    查看全文

• 作者：Chenyang Xing ; Liping Zhao ; Jichun You ; Wenyong Dong ; Xiaojun Cao ; Yongjin Li
• 刊名：The Journal of Physical Chemistry B
• 出版年：2012
• 出版时间：July 19, 2012
• 年：2012
• 卷：116
• 期：28
• 页码：8312-8320
• 全文大小：598K
• 年卷期：v.116,no.28(July 19, 2012)
• ISSN：1520-5207

文摘

The impact of pristine multiwalled carbon nanotubes (MWCNTs), an ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF₆], and the ionic liquid-modified MWCNTs (IL-MWCNTs) on the crystallization behavior of melt-crystallized poly(vinylidene fluoride) (PVDF) has been investigated. Pristine MWCNTs accelerate crystallization of PVDF as an efficient nucleation agent, while the formed crystals are mainly nonpolar 伪 crystal form with few polar 尾 crystals. Incorporation of only ionic liquid results in depression of the PVDF melt crystallization rate due to the miscibility of IL with PVDF but leads to a higher content of polar crystals (尾 and 纬 forms) than MWCNTs. The ionic liquid and MWCNTs show significant synergetic effects on both the nucleation and the formation of polar crystals for PVDF by melt crystallization. Addition of IL-MWCNTs not only improves the MWCNTs dispersion in PVDF matrix but also increases the overall crystallization rate of PVDF drastically. More important, the melt-crystallized PVDF nanocomposites with IL-MWCNTs show 100% polar polymorphs but no 伪 crystal forms. To the best of our knowledge, this is the first report on the achievements of full polar crystal form in the melt-crystallized PVDF without mechanical deformation or electric field. The IL to MWCNTs ratio and the IL-MWCNTs loading content effects on the crystallization behavior of PVDF in the nanocomposites were also studied. It is considered that the specific interactions between >CF₂ with the planar cationic imidazolium ring wrapped on the MWCNTs surface lead to the full zigzag conformations of PVDF; thus, nucleation in polar crystals (尾 and 纬 forms) lattice is achieved and full polar crystals are obtained by subsequent crystal growth from the nuclei.