不同比例的s-BPDA/i-BPDA型聚酰亚胺共聚结构与性能关系

由不同比例的二酐单体3,3′,4,4′-联苯四酸二酐(s-BPDA)/2,2′,3,3′-联苯四酸二酐(i-BPDA)与二胺单体4,4′-二氨基二苯醚(4,4′-ODA)制得了一系列共聚可溶聚酰亚胺. 采用DSC 、TGA和拉伸等测试方法对所得共聚聚酰亚胺进行了表征, 实验结果表明, 所得聚酰亚胺具有优异的力学性能和热稳定性, 并且随着i-BPDA含量的增加, 聚酰亚胺的溶解性提高, 玻璃化转变温度(Tg)升高, 中间体聚酰胺酸的固有黏度降低.     

引入三氟甲基侧基对对苯醚型聚酰亚胺薄膜吸水性及水蒸汽透过性的影响

合成了3种含三氟甲基的芳香二胺,进而与3,3′,4,4′-联苯四甲酸二酐(BPDA)缩聚,得到3种对苯醚型含氟聚酰亚胺薄膜,并由4,4′-二氨基二苯醚（4,4′-ODA）与BPDA缩聚得到聚酰亚胺薄膜。 对4种聚酰亚胺薄膜的水蒸汽透过率、吸水性和热学性能的测试结果表明,其中聚合物PI-1（2,2′-BTF-4,4′-BADE+BPDA;BTF：双三氟甲基;BADE：二氨基二苯醚）的水蒸汽透过率为7.70 g/（h·m2）,吸水率为0.67%,玻璃化转变温度为259.74 ℃,质量损失5%的温度为521.40 ℃,具有良好的水蒸汽透过性和低吸水性。     

查尔酮环氧树脂的合成及其固化性能

以4,4′-二羟基查尔酮为原料,和环氧氯丙烷反应合成了主链含有双键结构的查尔酮环氧树脂（CER），其结构经¹H NMR和FT-IR确证。采用非等温DSC法研究了甲基四氢邻苯二甲酸酐和4,4′-二氨基二苯基砜两种固化剂对CER的固化反应热行为，通过动态热机械分析和热失重分析对CER的热性能进行了研究。结果表明：甲基四氢邻苯二甲酸酐体系固化的CER的T_g为152.73 ℃,初始热分解温度为350.6 ℃， 800 ℃时的残碳率为19.29%； 4,4′-二氨基二苯基砜体系固化的CER的T_g为251.94 ℃,初始分解温度为365.7 ℃， 800 ℃时的残碳率为46.44%。     

一种新型磺化聚醚醚酮的合成、表征和性能

以特丁基对苯二酚、3,3′-二磺酸钠基-4,4′-二氟二苯酮和4,4′-二氟二苯酮为单体,制备了具有高磺化度的聚醚醚酮.该系列聚合物可溶,并具有良好的成膜性.对聚合物及其膜的一些性能进行了研究.     

可溶性共聚型聚苯并咪唑的合成及性能

以对苯二酚和对氟苯甲腈为原料, 合成了1,4-二(4-羧基苯氧基)苯, 并与4,4′-二羧基二苯醚作为共聚单体与3,3′-二氨基联苯胺反应合成了共聚型聚苯并咪唑, 通过红外光谱、核磁共振和热重分析等手段对聚合物的结构及热性能进行了分析. 研究了聚合物的黏度、溶解性、成膜性及聚合物薄膜的力学性能.     

新型两亲性混配钌配合物的合成及其对Hg2+的选择性“肉眼”识别

采用与文献不同的路线合成了4,4′-二(p-甲基苯基)-2,2′-二联吡啶,与文献结果相比,总收率由4.0%提高至15.3%.该化合物和4,4′-二羧基-2,2′-二联吡啶组成混合配体与金属钌配位,合成了两亲性、混配型配合物cis-N,N-4,4′-二(p-甲基)苯基-2,2′-二联吡啶-N,N-4,4′-二羧基-2,2′-二联吡啶-N,N-二异硫氰钌配合物,并用IR,UV-Vis,NMR和Maldi-TOF等手段进行表征.将该两亲性混配钌配合物首次用于对Hg2+的识别中,发现此配合物对Hg2+表现出灵敏的选择性“肉眼”识别:在DMF/乙醇溶液(体积比1∶9)中加入Hg2+后,MLCT态吸收由530nm蓝移到485nm.该配合物与Hg2+以1∶1(摩尔比)结合,检测限可低至0.5×10-6mol/L.     

含磷聚酰亚胺纤维的制备及其力学与阻燃性能

采用廉价的三苯基氧膦和混酸合成了一种含磷二胺单体,二（3-氨基苯基）苯基膦氧(DAPPO)。在4,4′-二胺基二苯醚（ODA）、3,3′,4,4′-联苯四酸二酐（BPDA）和均苯四酸二酐（PMDA）聚合体系中引入该单体,制备含磷聚酰亚胺纤维。热失重分析（TGA）结果表明,聚酰亚胺纤维的热稳定性随含磷量的增加而明显提高。当n（DAPPO）：n（ODA）为7：93时,纤维的极限氧指数达到了43,说明纤维的阻燃性能显著提高。     

双酚F型聚酰亚胺薄膜的制备与性能

以4-氯代酞酰亚胺和双酚F为原料,在N,N′-二甲基乙酰胺溶剂中,经水解、酸化、脱水,合成了一种新型的双酚F型二酐(BPFDA)单体,并用1H NMR和IR测试方法确认了其结构。 采用传统的一步法,用N,N′-二甲基乙酰胺作溶剂,BPFDA分别与4,4′-二氨基二苯醚（ODA）和4,4′-二氨基二苯甲烷（MDA）聚合,得到聚酰胺酸,并进一步热亚胺化得到聚酰亚胺薄膜,并对其进行了表征。 结果表明,BPFDA/ODA薄膜和BPFDA/MDA薄膜的玻璃化转变温度分别为200和204 ℃; 热失重分析表明,质量损失5%的温度分别为506.50和459.10 ℃;其拉伸强度分别为110和100 MPa。     

氨基呋咱氧化为氨基硝基呋咱的合成研究

研究开发了将氨基呋咱转化为氨基硝基呋咱新的高收率氧化方法. 采用甲烷磺酸为介质, 以过氧化氢、碱或碱土金属和胺为基的氧化物(如钨酸钠或过硫酸铵)混合物的新氧化体系[H2O2/CH3SO3H/Na2WO4或(NH4)2S2O8]代替以硫酸为介质的过氧化氢和过硫酸铵混合物氧化体系, 分别对3,4-二氨基呋咱(DAF)、3,3’-二氨基-4,4’-氧化偶氮呋咱(DAAF)和3,3’-二氨基-4,4’-偶氮呋咱(DAAzF)进行氧化, 以高于65%的产率获得了3-氨基-4-硝基呋咱(ANF)和3-氨基-3’-硝 基-4,4’-氧化偶氮呋咱(ANAF), 并以15%的收率合成得到新化合物3-氨基-3’-硝基-4,4’-偶氮呋咱(ANAzF). 研究表明甲烷磺酸/过氧化氢/碱或碱土金属和胺为基的氧化物混合物是制备同时含有氨基和硝基基团的系列呋咱化合物非常有效的氧化体系.     

双(对-氨基苯基)-2,3,7,8,12,13,17,18-八甲基卟啉及其金属衍生物的合成与表征

从3-甲基-2,4-戊二酮出发,经多步反应合成了3,3′,4,4′-四-甲基-2,2′-二吡咯基甲烷(TMDPM),改进了合成TMDPM的脱羧反应.研究了TMDPM与对-硝基苯甲醛反应合成meso-5,15-双-苯基-卟啉反应,发现对-甲基苯磺酸是卟啉原合成的良好催化剂,2,3-二-氯-5,6二氰基-1,4-苯醌是将卟啉原转化为卟啉的良好氧化剂;硝基卟啉经SnCl₂还原成氨基卟啉后,用固-液抽提进行氨基卟啉的纯化,得到了5,15-双(对-硝基苯基)-2,3,7,8,12,13,17,18-八甲基卟啉、5,15-双(对-氨基苯基)-2,3,7,8,12,13,17,18-八甲基卟啉及其金属衍生物,并表征了其结构     

Alignment control of liquid crystals on surface relief gratings

Liquid crystal alignment layers of a high T_g polymer containing an azobenzene moiety are prepared by photofabrication of a surface relief grating (SRG). The interference pattern of a circular and linearly polarized Ar⁺ laser beam generated the surface relief grating and the morphology was detected by atomic force microscope. The optical anisotropy of the films was investigated by polarizing optical microscopy. The orientation of the optical axis of the film mainly depends on the direction of the initial polarization plane. Nematic liquid crystals were aligned parallel to the direction of the grating, but the pretilt angles of the liquid crystals were nearly zero. Irradiation with homogeneous linearly polarized light could also align liquid crystals, but this alignment capability was weaker than that of the SRG film.     

Physical processes in azobenzene polymers on irradiation with polarized light

Azobenzenes can serve as model compounds for the study of transcis isomerization in more complex molecules. We have performed time-resolved spectroscopy in solutions containing free azobenzene chromophores and diols with a view to obtaining the energy levels and lifetimes of the excited states. A transition route based on experimental results for the theoretically calculated energy level scheme is proposed. Physical observations of surface relief in thin films of azobenzene polymers when irradiated with polarized light are reported. These include two beam polarization holographic observations and single beam transmission measurements through a mask, followed by atomic force microscope and profiler investigations. It is concluded that none of the prevalent theories can explain all the observed facts.     

Alignment control of liquid crystals on surface relief gratings

Liquid crystal alignment layers of a high T _g polymer containing an azobenzene moiety are prepared by photofabrication of a surface relief grating (SRG). The interference pattern of a circular and linearly polarized Ar⁺ laser beam generated the surface relief grating and the morphology was detected by atomic force microscope. The optical anisotropy of the films was investigated by polarizing optical microscopy. The orientation of the optical axis of the film mainly depends on the direction of the initial polarization plane. Nematic liquid crystals were aligned parallel to the direction of the grating, but the pretilt angles of the liquid crystals were nearly zero. Irradiation with homogeneous linearly polarized light could also align liquid crystals, but this alignment capability was weaker than that of the SRG film.     

Role of the Fermi surface in adsorbate-metal interactions: an energy decomposition analysis

We present the result of a fragment-based energy decomposition analysis on some molecule-surface interactions. The analysis allows us to quantify the Pauli repulsion, its relief, and the attractive orbital interaction energy. In a metal, the existence of incompletely occupied energy bands causes significant relief of the Pauli repulsion due to escape of antibonding electrons to unoccupied states at the Fermi energy. This is the key electronic structure feature of metals that causes metal-molecule bond energies to be stronger and dissociation barriers of chemisorbed molecules to be much lower than those in comparable systems with no or one metal atom. As examples, we discuss the energy decomposition for the activated dissociation of hydrogen on the Cu surface and its unactivated dissociation on Pd, and for the (activated) chemisorption of N2 on W. We show that in all cases the relief of Pauli repulsion is of crucial importance for the chemisorption energy and for the low (or nonexistent) dissociation barriers. The barrier to the chemisorption well for nitrogen on tungsten is clearly related to a late relief of the Pauli repulsion. The relief of Pauli repulsion is important in lowering the barrier to dissociation of H2 on both Cu and Pd, but the difference in barrier heights for Cu and Pd appears to not be due to stronger relief of Pauli repulsion on Pd but primarily to the Pauli repulsion itself being stronger on Cu than on Pd, the relief energy being quite comparable on the two metals.     

Analysis of the kinetics of diffraction efficiency during the holographic grating recording in azobenzene functionalized polymers

The laser-assisted holographic grating recording process in films of azobenzene functionalized polymers is usually studied by observation of the efficiency of light scattering on a developing in time diffraction grating. Various possible mechanisms contributing to grating formation as well as the bulk or surface origin (bulk refractive index and/or relief grating) of light scattering make the analysis of kinetics of grating recording, from the light scattering data only, difficult and ambiguous. To fully explain experimentally observed various and complex (frequently nonexponential) kinetics of the first-order light diffraction intensity, we considered a simple single-exponential growth of the two phase gratings in the same polymer film. In modeling we assumed that the bulk refractive index grating Deltan(t) and the surface relief grating Deltad(t) differ considerably in their growth rates and we allowed for a nonstationary phase shift Deltaphi(t) between them which was experimentally observed during the recording process. The origin of the nonstationary phase shift is a result of a slow shift of interference pattern due to delicate symmetry breaking in illumination conditions (e.g., difference in beam intensities and deviation of exact symmetrical beam incidence angles on the sample). Changing only such parameters as stationary amplitudes of refractive index and relief gratings for a span of phase shifts (0-pi) between them, we obtained a series of kinetic responses which we discuss and interpret. The various examples of temporal evolution of diffraction efficiency for the same grating formation kinetics, modeled in our work, supply evidence that great care must be taken to properly interpret the experimental results.     

Thermally stable holographic surface relief gratings and switchable optical anisotropy in films of an azobenzene-containing polyelectrolyte

In a search for effective polymer film material for holographic surface patterning, commercially available azobenzene polyelectrolyte has been employed. Films of good optical quality in a wide range of thickness were produced. Optical dichroism up to 0.19 was induced upon irradiation with linearly polarized light. Surface relief gratings with amplitudes up to 630 nm and diffraction efficiency of 37% were inscribed by holographic exposure to the light of 488 nm. Due to the ionic nature of the material, the relief was stable at least up to the temperature of decomposition (ca. 200 degrees C) but could be erased and inscribed again by light.     

Mass migration on a polymer surface caused by photoinduced molecular rotation

We demonstrated the formation of a photoinduced surface relief grating using thin films comprising a photochromic molecular motor, 9-(2-phenyl-2,3-dihydro-cyclopenta[a]naphthalen-1-ylidene)-9H-fluorene. Results show that mass migration occurred by patterned light irradiation prepared from interfered laser beams and a photomask.