Cubic nonlinear optics of polymer thin films. Effects of structure and dispersion on the nonlinear optical properties of aromatic Schiff base polymers
Cubic nonlinear optics of polymer thin films. Effects of structure and dispersion on the nonlinear optical properties of aromatic Schiff base polymers
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聚合物薄膜的立方非线性光学。
DOI：
10.1021/cm00018a001
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发表时间：
1991
影响因子：
8.6
通讯作者：
J. Meth
中科院分区：
文献类型：
--
作者：
S. Jenekhe;Chen;H. Vanherzeele;J. Meth
共轭芳族席夫碱聚合物或聚（偶氮甲碱）是热稳定的成膜和成纤材料，在浓硫酸或甲磺酸中表现出良好的机械强度、热致液晶性和溶致液晶性。 1" 3 尽管芳香族聚（偶氮甲碱）的这些特征已经被研究了很多年，1" 3 此类聚合物的详细结构和固态性质之前尚未被研究过，因为它们通常不溶解，除了在强浓酸中，在强浓酸中它们由于希夫碱（-CH=N-）的水解而迅速降解。我们最近报道了一系列共轭芳香族聚（偶氮甲碱）的可溶性配合物的制备及其溶液加工成光学品质的薄膜，该薄膜适用于表征 (1)(a) D’Alelio, G. F.；克里韦洛合资企业；舍尼格，R.K.； Huemmer，T.F.J.Macromol。科学。 1967 年，Al，1161-1249。(b) D’Alelio，G.F.；斯特拉兹克，WF；费格尔，D.M.； Schoenig，R. KJ Macromol。科学。化学。 1968, 2, 1457.(c) D’Alelio, G. F.； Schoenig，R. KJ Macromol。科学。 Rev.：大分子色甘醇。化学。 1969 年，C3，105-234。(2) 摩根，P.W.； Kwolek，S.L； Fletcher, T. C.《高分子》 1987, 20, 729-739.(3)(a) Millaud, B.；蒂埃里，A.；斯库利奥斯，A.莫尔。水晶。液体。水晶，利特。 1978, 41, 263-268.(b) 诺埃尔，C.；比拉德，J.Mol。水晶。液体。水晶，利特。 1978, 41, 269-274。聚合物。 4 5在这里，我们将报告我们对共轭芳香聚（偶氮甲碱）两种成员的三阶非线性光学性质的初步研究，以探讨结构和波长色散对聚合物薄膜的立方非线性光学的影响。我们对这些芳香族席夫碱聚合物作为三阶非线性光学材料的兴趣部分基于其独特且丰富的分子结构[(-Rj-N= CH-)„和(-R-N= CH-R2-CH= N-)„]以及它们与其他对亚苯基聚合物的关系。席夫碱聚合物主链中的Rt和R2基团可以在相当大的范围内变化，因为通过缩聚制备聚合物可以容易获得二胺和二醛。因此，此类聚合物非常适合研究结构-非线性光学性质关系，共轭芳香族聚（偶氮甲碱）与聚对亚苯基亚乙烯基（PPV）及其衍生物具有等电子性，其电子结构和非线性光学性质已得到广泛研究 6"" 9 例如，PPV 及其 2, 5-二甲氧基衍生物 (PDMOPV) 的薄膜通过三次谐波测量具有 7.8 X 的 (3) 值。 1.85 pm 处分别为 10" 12 和 5.4 X 10" 11 esu。 7 8高度取向的 PPV 薄膜在 1.85 pm 处具有 (3) 1.5 X 10'10 esu。 9 根据理论预测的 10 非谐效应，可以预期共轭芳香族聚（偶氮甲碱）具有较大的三阶光学非线性。 (4)(a) Yang, C. J.；Jenekhe, S. A. Mater.，正在出版，(b) Yang, C. J.；Jenekhe, S. A.，手稿正在准备中。(5) Antoun, S.；Lenz, RW J. Polym. 1809-1817。
The conjugated aromatic Schiff base polymers or poly-(azomethines) are thermally stable film-and fiber-forming materials that exhibit good mechanical strength, thermotropic liquid crystallinity, and lyotropic liquid crystallinity in concentrated sulfuric or methanesulfonic acid. 1" 3 Al-though these features of the aromatic poly (azomethines) have been investigated for many years, 1" 3 the detailed structure and solid-state properties of this class of polymers have not been previously studied because of their general insolubility except in strong concentrated acids in which they rapidly degrade due to thehydrolysis of the Schiff base (—CH= N—). We recently reported the preparation of soluble complexes of a series of conjugated aromatic poly (azomethines) and their solution processing tooptical-quality thin films suitable for characterization of linear optical, nonlinear optical, and electronic properties of the (1)(a) D’Alelio, G. F.; Crivello, JV; Schoenig, R. K.; Huemmer, T. F. J. Macromol. Sci. 1967, Al, 1161-1249.(b) D’Alelio, G. F.; Strazik, WF; Feigl, D. M.; Schoenig, R. KJ Macromol. Sci. Chem. 1968, 2, 1457.(c) D’Alelio, G. F.; Schoenig, R. KJ Macromol. Sci. Rev.: Ma-cromol. Chem. 1969, C3, 105-234.(2) Morgan, P. W.; Kwolek, S. L; Fletcher, T. C. Macromolecules 1987, 20, 729-739.(3)(a) Millaud, B.; Thierry, A.; Skoulios, A. Mol. Cryst. Liq. Cryst., Lett. 1978, 41, 263-268.(b) Noel, C.; Billard, J. Mol. Cryst. Liq. Cryst., Lett. 1978, 41, 269-274. polymers. 4 5Here, we will report on our initial study of the third-order nonlinear optical properties of two members of the conjugated aromatic poly (azomethines) to explore the effects of structure and wavelength dispersion on the cubic nonlinear optics of polymer thin films. Our interest in these aromatic Schiff base polymers as third-order nonlinear optical materials is based in part on their unique and rich molecular structures [(—Rj—N= CH—)„and (—R—N= CH—R2—CH= N—)„] and their relationship to other p-phenylene polymers. The Rt and R2 groups in the Schiff base polymer backbones can be varied with considerable lattitude because of the readily obtainable diamines and dialdehydes from which the polymers are made by condensation polymerization. Thus, such a class of polymers is ideal for investigating struc-ture-nonlinear optical property relationships. The con-jugated aromatic poly (azomethines) are isoelectronic with poly (p-phenylenevinylene)(PPV) and derivatives whose electronic structure and nonlinear optical properties have been widely investigated. 6"" 9 For example, filmsof PPV and its 2, 5-dimethoxyderivative (PDMOPV) have (3) values, measured by third harmonic generation, of 7.8 X 10" 12 and 5.4 X 10" 11 esu, respectively, at 1.85 pm. 7 8Highly oriented PPV films have a (3) of 1.5 X 10'10 esu at 1.85 pm. 9 Similarly large third-order optical nonlinearities can be expected in conjugated aromatic poly (azomethines). On the basis of the theoretically predicted10 anharmonicity effect on< 3), the aromatic poly (azomethines) might be (4)(a) Yang, C. J.; Jenekhe, S. A. Chem. Mater., in press,(b) Yang, C. J.; Jenekhe, S. A., manuscript in preparation.(5) Antoun, S.; Karasz, FE; Lenz, RW J. Polym. Sci.: A: Polym. Chem. 1988, 26, 1809-1817.