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研究了各种催化体系、催化剂浓度及聚合条件对催化效率(f)和聚乙炔分子量()的影响。发现Nd(i-OC_3H_7)-AlR_3(R=C_2H_5,i-C_4H_9)催化体系可获得较大的可溶分数(q)。催化剂浓度、Al/Nd克分子比和聚合温度对f、及q均有一定影响。可溶性Nd(i-OC_3H_7)_3-AlR_3催化体系的UV光谱证实、Nd的价态与AlR_3混合与AlR_3混合后保持不变。PA的IR光谱示出,Nd(i-OC_3H_7)_3-Al(C_2H_5)_3及Nd(i-OC_3H_7)_3-Al(i-C_4H_9)_3体系获得的聚合物分别含有CH_3CH_2—和(CH_3)_2CHCH_2—末端基。上述结果表明,乙炔的聚合可能是通过单体在Nd-C键之间的插入进行的。 相似文献
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本文采用引入外场微扰的CNDO/S—CI方法,计算了一系列苯衍生物的分子二阶非线性光学系数,探讨了取代基的电子性质、取代位置及取代基数目对分子二阶非线性光学系数的影响.结果表明;取代基的供电能力越强,分子的二阶非线性光学系数越大.D,A对位二取代苯和1—D,2.4—A,A三取代苯具有较高的非线性光学效应,苯衍生物中取代基数目为3时分子具有最佳的非线性光学效应.文中还对上述结论给出了初步的理论解释. 相似文献
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合成了苯基乙烯基亚砜 (PVSO) ,并以萘 碱金属作为引发剂、丁二酸酐作为终止剂 ,进行阴离子聚合 ,制备出单分散、端羧酸盐的苯基乙烯基亚砜的遥爪聚合物 ,聚合物的功能度基本在 1 6 0以上 .在真空加热条件下 ,聚苯基乙烯基亚砜发生侧基热消除反应 ,从而获得末端为羧酸盐的遥爪聚乙炔 相似文献
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偶氮苯侧链结构对聚丙烯酸酯三阶非线性光学性能影响 总被引:6,自引:0,他引:6
设计合成了一系列含偶氮苯非线性生色团的丙烯酸酯,并采用溶液聚合法合成了功能化的聚丙烯酸酯,利用FTIR、NMR、UV等对化合物的结构进行了表征,证实得到了指定结构的化合物.利用Z扫描技术对合成的聚丙烯酸酯的非线性光学性能进行了研究,通过对聚合物的非线性光学吸收拟合,计算得到非线性吸收系数β和三阶非线性系数χ(3),并探讨了取代基生色团分子结构与高分子三阶非线性光学性能的关系,结果显示增大侧链生色团π电子离域长度或强DπA(推拉基团)结构均可有效提高聚合物的三阶非线性光学性能. 相似文献
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聚乙炔(PA)的电导率X(Ω~(-1).cm~(-1))经掺杂可以在十二个数量级内变化。PA导电机理与一般的无机导体或半导体不同,PA通过荷电孤子与中性孤子之间的电子跃迁导电,而掺杂剂参与可增大这种跃迁的几率。掺杂剂与PA之间存在着相互作用,并由此而引起PA多种性质的变化。深入研究PA链间通过掺杂原子(或分子)进行的相互作用以及电荷传递过程,对于进一步揭示PA的垂直电导率产生的本质有着十分重要的意义。 相似文献
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《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1427-1443
Three different series of twin nonlinear optic (NLO) molecules were studied, in which the two NLO chromophores are linked by a central flexible polymethylene spacer. The first series, which had two azobenzene chromophores (Azo-twins), was designed to also exhibit liquid crystallinity. Most of the members of this series exhibited a nematic mesophase. The second series had two 4-nitrophenol units as chromphores (PNP-twins), while the third one was based on 4-alkylsulfonyl-4'-alkoxy azobenzene chromophores (Sulfazo-twins). These twin NLO systems exhibited interesting odd-even oscillations in their second harmonic generation (SHG) efficiencies in the powder form. When the spacer had an odd number of methylene groups, they exhibited significantly higher powder SHG efficiency than their even counterparts, with the even ones most often exhibiting no detectable SH signal. Preliminary single crystal X-ray diffraction studies performed on the PNP-twin series showed that while the even members possess a molecular center of symmetry and pack centro-symmetrically, the odd ones do not, leading to the observed alternation. The orientational-disordering dynamics of two of the twin series – the PNP and the Sulfazo-twin series, doped in a poly(methyl methacrylate) matrix, was also studied by monitoring the SH-signal decay in electric field poled samples. Interestingly, the maximum attainable SH signal, χ(2), in the poled samples also showed an odd-even oscillation with the odd ones again exhibiting a higher value of χ(2). The temporal stability of the SHG intensity at 70°C, after the removal of the applied corona, was also studied and the relaxation of the chromophores was found to follow a biexponential decay. The slower relaxation component exhibits a spacer length dependence, which suggests the interplay of two factors in governing the temporal stability in such polymer doped twin systems, one is the conformational discomfort experienced by the spacer in adopting a U-shaped geometry, and the other the electrostatic repulsion when two aligned dipoles lie very close to each other. 相似文献
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D. Udayakumar A. John Kiran A. Vasudeva Adhikari K. Chandrasekharan G. Umesh H.D. Shashikala 《Chemical physics》2006
The third-order nonlinear optical properties of newly synthesized soluble polyoxadiazoles containing 3,4-dialkoxythiophenes were investigated by using Z-scan and degenerate four-wave mixing (DFWM) techniques. The measurements were performed at 532 nm with 7 ns pulses from a Nd:YAG laser. We found a good agreement between the values of χ(3) determined from both the experiments. Z-scan results indicate a negative nonlinear refractive index, n2, whose magnitude is of the order of 10−10 esu for all the copolymers. The variation of nonlinear response among the copolymers clearly indicates the dependence of χ(3) on donor and acceptor type of units present in these copolymers. The copolymers exhibit strong reverse saturable absorption and good optical limiting properties at 532 nm. 相似文献
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The nonlinear absorption and refraction of soluble phthalocyanines and naphthalocyanines have been measured with z-scan technique using 8 ns, 532 nm laser pulses. The excited-state absorption cross-section and the excited-state refractive-index cross section have been estimated under the consideration of laser induced thermal effect. The excited state absorption induced n2 and Re χ(3) values are in the range of 10?12 esu. These observed data are enhanced by the concentrations of both metal substituted Pc's and Nc's, but this increment became very small for the metal free phthalocyanine. During the optical limiting experiments, a 25% linear transmitted solution of R8PcH2 can limit laser pulses to ≤ 120 μJ from incident energies as high as 2.0 mJ, and this limitation moved down to ≤ 50 μJ when replacing R8PcCu from P8PcH2. A similar property has also been observed for the metal substituted naphthalocyanines. The results indicate that both the nonlinear refraction and optical limiting properties should be strongly affected by the metal induced triplet-state nonlinear absorption in both Pc's and Nc's. Moreover, the laser pulses created a self trapped filament inside the solution of this optical limiter, while emitting time-resolved, concentric rings on a projection screen, which could be induced by the thermal lensing effect. The various optical nonlinear properties observed from these materials should make them valuable as an optical limiter. 相似文献
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PREPARATION AND SECOND-ORDER OPTICAL NONLINEARITY OF NOVEL PHENOXYSILICON NETWORKS BY SOL-GEL PROCESS** 总被引:1,自引:0,他引:1
Four phenoxysilicon networks for nonlinear optical (NLO) applications were designed and prepared by an extended sol-gel process without additional H2O and catalyst. All poled polymer network films possess high second-order nonlinear optical coefficients (d33) of 10-?~10-8 esu. The investigation of NLO temporal stability at room temperature and elevated temperature (120℃) indicated that these films exhibit high d33 stability because the orientation of the chromophores are locked in the phenoxysilicon organic/inorganic networks. 相似文献
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OPTICAL PHASE CONJUGATION RESPONSE OF PHOTOINDUCED POLYMER FILMS CONTAINING AZOBENZENE MOIETIES WITH CHIRAL GROUP 总被引:2,自引:0,他引:2
An optically active monomer containing azobenzene moieties with chiral group (s-2-methyl-butyl), 4-[2-(methacryloyloxy)ethyloxy]-4'-(s-2-methyl-1-butyloxycarbonyl) azobenzene(Ml) was synthesized. Polymer (PMl)possessing optical phase conjugated response was obtained by homopolymerzation of the optically active monomer (Ml)using free radical polymerization. The polymer was very soluble in common solvents and good optical quality films could beeasily fabricated by spin coating. The optical phase conjugated responses of the polymer PM1 were measured by degeneratefour-wave mixing (DFWM). In comparison with polymer containing no chiral group, it was found from the preliminarymeasurement of photoisomeric change that optical phase conjugated response of the PM1 in the long-range order hexagonalsymmetry microstructure could be easily controlled by choosing the appropriate polarization direction of the irradiatingbeams (514.5 nm) and the irradiating number, presumably due to the chiral group in the PM1 molecular structure. For thecase of the polymer investigated here, a chiral group side chain was introduced to increase optical phase conjugated responseintensity with different polarization directions of the irradiating beams, which aims originally at searching for a new photo-ative material. 相似文献