Kropewnicki Michelle L, Schaefer Dieter J, Hehn Manfred, Dermaut Wim, Geise Herman J, Chmelka Bradley F
Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
Solid State Nucl Magn Reson. 2002 Sep-Nov;22(2-3):275-97. doi: 10.1006/snmr.2002.0082.
The properties of poly(p-phenylene vinylene) (PPV) films depend on the degree of orientational order present in the films. Recently, Dermaut et al. reported a novel cold-stretching technique (Macromolecules 33, 5634-5637 (2000)) in which chain alignment can be introduced into PPV precursor films by uniaxially stretching them prior to the thermal elimination reaction that forms PPV. The two-dimensional direction exchange with correlation for orientation-distribution evaluation and reconstruction (DECODER) 13C NMR technique was applied to both unstretched PPV films and PPV films that were uniaxially cold stretched to a draw ratio lambda = l/l0 = 5. The unstretched films were found to be moderately ordered, comprised of a component present at 80% with a Gaussian distribution of 60 degrees fwhm, while the remaining 20% is isotropically distributed. A distribution of 9 degrees +/- 3 degrees fwhm was measured by NMR in good agreement with IR dichroism measurements for the uniaxially cold-stretched films, establishing that a high degree of orientational order can be introduced by cold stretching PPV films.
聚对苯撑乙烯（PPV）薄膜的性质取决于薄膜中存在的取向有序程度。最近，德马乌特等人报道了一种新型的冷拉伸技术（《大分子》33, 5634 - 5637 (2000)），在该技术中，在形成PPV的热消除反应之前，通过单轴拉伸PPV前驱体薄膜，可以将链排列引入其中。二维方向交换与取向分布评估和重建相关（DECODER）13C NMR技术被应用于未拉伸的PPV薄膜以及单轴冷拉伸至拉伸比λ = l/l0 = 5的PPV薄膜。发现未拉伸的薄膜具有适度的有序性，由80%的一种成分组成，其高斯分布的半高宽为60度，而其余20%呈各向同性分布。通过NMR测量得到的半高宽为9度±3度，与单轴冷拉伸薄膜的红外二向色性测量结果高度一致，这表明通过冷拉伸PPV薄膜可以引入高度的取向有序性。
