Anisotropic Polymer Conformations in Aligned SWCNT/PS Nanocomposites.
Anisotropic Polymer Conformations in Aligned SWCNT/PS Nanocomposites.
复制标题
对齐的 SWCNT/PS 纳米复合材料中的各向异性聚合物构象。
DOI：
10.1021/acsmacrolett.5b00256
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发表时间：
2015
影响因子：
7.015
通讯作者：
Tung WS
中科院分区：
文献类型：
--
作者：
Tung WS
在各向同性单壁碳纳米管/聚合物纳米复合材料中，聚合物的旋转半径随着碳纳米管浓度的增加而增加。通过熔融纤维纺丝对纳米复合材料中的SWCNTs进行排列，发现聚合物链的构象是各向异性的。利用SAXS和SANS，发现各向异性swcnts网格在垂直于对准方向的方向上的网格尺寸小于沿对准方向的网格尺寸。在固定的swcnts方向下，使用SANS分别探测平行于和垂直于对准方向rgparr和rgper的旋转半径。随着单壁碳纳米管浓度的增加，rgper的增加幅度明显大于rgpar，各向异性的程度随着单壁碳纳米管浓度的增加而增加。聚合物的各向异性构象在垂直于取向方向的方向上更大，这对应于较小的swcnts网格尺寸。因此，当SWCNTs浓度和排列相结合，产生比未受扰动时更小的SWCNTs网格尺寸时，聚合物构象通过采用更大的网格来绕过SWCNTs。在棒状纳米颗粒纳米复合材料中，聚合物构象的变化对纠缠密度、聚合物动力学和力学性能具有重要影响。
Polymer radii of gyration in isotropic single-walled carbon nanotube (SWCNT)/polymer nanocomposites were previously found to increase with increasing SWCNT concentration. Here, the SWCNTs in nanocomposites were aligned by melt fiber spinning, and the polymer chain conformations were found to be anisotropic. Using SAXS and SANS, the anisotropic SWCNT meshes were found to have smaller mesh sizes in the direction perpendicular to the alignment direction than along the alignment direction. At fixed SWCNT orientation, the radius of gyration was probed parallel and perpendicular to the alignment direction,RgparandRgper, respectively, using SANS. With increasing SWCNT concentration,Rgperincreases significantly more thanRgpar, such that the extent of anisotropy increases with SWCNT concentration. The anisotropic polymer conformation is larger in the direction perpendicular to the alignment direction, which corresponds to a smaller SWCNT mesh size. Thus, when the SWCNT concentration and alignment combine to produce a SWCNT mesh size that is smaller than the unperturbedRg, the polymer conformation circumvents the SWCNTs by adopting a largerRg. Changes in the polymer conformation in nanocomposites with rod-like nanoparticles has important ramifications for entanglement density, polymer dynamics, and mechanical properties.