【作者】 张晓龙；

【导师】 崔占臣；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2011， 博士

【摘要】 任何技术的进步都与相应领域材料的发展密切相关。二阶非线性光学材料在高速光通讯、光信息处理和光电子学等实用领域中的应用前景受到越来越广泛的重视。作为光电调制波导器件的基础,二阶非线性光学材料的研究正成为科学家们关注的热点。在光电领域中,设计具有大的分子非线性性质的有机分子仍然面临着巨大的挑战。除了高的分子非线性光学响应外,在许多光学应用方面,还要求材料要有很好的热稳定性和在光通讯波长区域内具有很好的透明性。通常,设计新的非线性材料时主要考虑的参数是生色团分子固有的非线性效率。影响非线性效率的主要因素是生色团分子之间的静电相互作用。这种相互作用不但与生色团分子的给电子基团、供电子基团、π电子共轭桥有关,还与生色团分子的形状有很大关系。实验和理论研究证明球形生色团分子在非线性材料中起到了非常重要的作用,球形生色团对于非线性材料来说可能是理想的形状。这是在聚合物体系中减少偶极-偶极相互作用和改进极化效率的有效方法。本论文正是基于这一思路,主要包括以下几部分研究工作：第二章设计合成了一系列的含氟和不含氟的二维纺锤形生色团分子,并把这些二维纺锤形生色团分子应用于主客体掺杂体系中来制备二阶非线性光学薄膜；第三章设计合成了一系列含有二维纺锤形生色团分子的聚氨酯,并制备出了PU/Poly(MMA-co-GMA)掺杂型非线性光学交联膜；第四章的工作是利用二维纺锤形生色团分子制备出了可紫外光固化交联的非线性光学薄膜和通过溶胶-凝胶法制备出了有机／无机光学杂化薄膜。更多还原

【Abstract】 Second-order nonlinear optical (NLO) materials have attracted considerable attention due to their potential applications in broad bandwidth telecommunication, information processing, and high-density optical storage, etc. Electro-optic (EO) materials, which possess large and rapid NLO responses, low dielectric constant, high laser damage thresholds, low cost, superior chemical flexibility and ease of process, have been predicted to be the NLO polymers closest to commercialization. Especially organic second-order nonlinear chromophore acquired an enormous progress. A lot of molecules with large hyperpolarizabilities and excellent thermal and chemical stability were designed and synthesized. Before their commercialization, it is a challenge to synthesize EO polymers with large NLO effects, high thermal stability of the dipole moment after poling and low optical loss to fit the requirements of EO apparatus.In this dissertation, we have provided some promising attempts to synthesize novel organic chromophores. We present the synthesis of a series of two-dimensional spindle-type chromophores. The chromophores were used to prepare host-guest doped second-order nonlinear optical films. We designed and synthesized a series of PU based on spindle-type chromophores, and the PU/Poly(MMA-co-GMA) doped cross-linked films were prepared. We have successfully synthesized novel photo-cross-linked NLO materials (PU/PMMA) containing spindle-type chromophores. Second-order nonlinear optical organic/inorganic hybrid film containing two-dimensional spindle-type chromophores was successfully prepared via sol-gel process.In chapter 2, we present the synthesis, characterization of two-dimensional spindle-type chromophores STC-1 to STC-4. The two-dimensional spindle-type chromophores were accomplished by three different strategies:Suzuki cross-coupling reaction, Wittig reaction, Knoevenagel condensation reaction. All of the compounds were characterized by 1H-NMR spectrum and IR spectrum. Thermogravimetric analysis showed that two-dimensional spindle-type chromophores exhibited good thermal stability. All of the absorption wavelengths (λmax) of chromophores were less than 480 nm, which proved that the chromophores possessed good transparency in the visible region. The host-guest doped second-order nonlinear optical films were prepared by the chromophores and Poly(GMA-co-MMA). The cross-linked network structure formed in films after poling process. The EO coefficients of the guest-host doped films were measured with the Teng-Man setup. The temporal stability of EO response was found to be good, as the r33 value of the films maintained more than 85% of their original value after holding at 80℃in air over 200 h.In chapter 2, we also present the synthesis of two-dimensional fluorinated spindle-type chromophores STC-1F and STC-2F. Dimethylamine was used as electron donor and 3,4,5-trifluorophenyl was used as side groups for chromophores STC-1 and STC-2 investigated. Chromophore STC-1 with TDC as electeron acceptor and chromphore STC-2 with 4-nitrobenzylcyanid as electeron acceptor were investigated. Two-dimensional fluorinated chromophores were characterized by 1H-NMR,19F-NMR and IR spectrum. Thermogravimetric analysis showed that the chromophores displayed high thermal stability. The maximum absorption wavelength (λmax= 482 nm) of fluorinated chromophore STC-1 was blue shift 8 nm in comparison with the nonfluorinated chromophore (λmax= 490 nm) in chloroform, which increased the optical transparency in the visible region. The guest-host doped films were prepared by the chromophores and PMMA. To further explore the alignment of the chromophore moieties in the chromophores/PMMA poled films, the order parameter (Φ) was measured. STC-1 F/PMMA doped films exhibited very highΦvalues, up to 0.26 higher than 0.17 for STC-2F/PMMA doped film. The testedΦvalues were well in accordance with their r33 values.In chapter 3, we designed and synthesized a series of PU based on spindle-type chromophores. All of the copolymers were characterized by 1H-NMR and IR spectrum. The molecular weight and molecular weight distribution were determined by gel permeation chromatography-refractive index-multi-angle laser light scattering detection techniques. DSC thermograms showed that polyurethanes generally have different Tg with different content of chromophores. PU-4 and PU-DR19 have the same content of chromophores, but the Tg of PU-4 is higher than PU-DR19. The relatively higher Tg of PU-4 might be caused by its rigid main-chain structure. In order to enhance the thermal and temporal stabilities of the NLO materials, the PU/Poly(MMA-co-GMA) doped cross-linked films were prepared. The surface morphology of the films was characterized by the AFM images. The surface of the films was extremely flat before poling. But the surface of the films resulted in numerous hills and valleys after poling, which caused by the chromophore moieties alignment in the poling direction. The EO coefficient of PU-2/Poly(MMA-co-GMA) cross-linked film was obtained up to 32 pm/V. Compared with their analogue copolymer containing DR-19, they displayed much better EO coefficient and thermal stability due to their large hyperpolarizability and unique structure. In chapter 4, we synthesized PU with double-ended photo-cross-linkable groups containing spindle-type chromophores. A preliminary study of the NLO properties of the cross-linked film is presented. The PU was prepared by 2-hydroxyethyl methacrylate (2-HEMA) and NCO-terminated chromophore, which was obtained from an addition reaction of spindle-type chromophore with an excess amount of 4,4’-Methylenebis (cyclohexyl isocyanate). The chemistry reaction course was characterized by IR spectrum. TGA thermograms showed that the temperature of the 5% weight loss was 212℃and 228℃for before and after photo-cross-linking, respectively. This result indicated that the cross-linked network structure can be benefited its stability against heating. The second-order optical property of the prepared film was measured by Teng-Man technique and achieved a high EO coefficient up to 41 pm/V. The thermal and temporal stability of the film was improved by photo-cross-linking. The functionalized alkoxysilane dye (ICTES-STC) was formed by the reaction of two-dimensional spindle-type chromophores (STC) with 3-isocyanatopropyltriethoxysilane (ICTES). Second-order nonlinear optical organic/inorganic hybrid film containing two-dimensional spindle-type chromophores was successfully prepared via sol-gel process. The thermogravimetric analysis showed that the initial decomposition temperature of the hybrid film is 269℃. This result indicates that the covalent linkage between the chromophore and silica matrix could prevent the decomposition of the chromophore. After corona poling, the EO coefficient of the hybrid film was calculated to be around 12 pm/V. The results showed that the hybrid film exhibited excellent thermal stability and NLO property.更多还原