Study on side-chain second-order nonlinear optical polyimides based on novel chromophore-containing diamines. I. Synthesis and characterization

Side-chain second-order nonlinear optical polyimides were prepared from four novel chromophore-containing diamines and 4,4′-(hexafluoroisopropylidene) diphthalic anhydride by a traditional two-step process that included a solution polycondensation followed by a chemical imidization. The four diamines were 2,4-di-β-aminoethylamino-6-p-nitrophenylamino-1,3,5-triazine (M1), 4-nitro-4′-[N-(4,6-di-β-aminoethylamino)-1,3,5-triazin-2-yl]amino azobenzene (M2), 2,4-di-p-aminophenylamino-6-p-nitrophenylamino-1,3,5-triazine (M3), and 4-nitro-4′-[N-(4,6- di-4-aminophenylamino)-1,3,5-triazin-2-yl]amino azobenzene (M4). All the polyimides exhibited maximum ultraviolet-visible absorption peaks or shoulders of chromophores at wavelengths below 400 nm, and those based on M1 and M3 were transparent at wavelengths above 450 nm, whereas those based on M2 and M4 were transparent at wavelengths above 550 nm. The polyimides possessed high glass-transition temperatures (T_g's; 218–247 °C) and thermal decomposition temperatures. They were soluble in aprotic solvents such as N-methyl-2-pyrrolidone, N,N-dimethyl acetamide, N,N-dimethyl formamide, and dimethylsulfone. Some were even soluble in common low-boiling-point solvents such as tetrahydrofuran. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4330–4336, 1999     

THE EFFECT OF PHOTO-CROSSLINKING ON THE ORIENTATION STABILITY OF POLYVINYL ALCOHOL CONTAINING 4-NITRO-4′-ALKOXYSTILBENE AND CINNAMYL PENDENT GROUPS*

Crosslinking is one of the effective routes for improving the orientation stability of poledpolymer films. The derivative of polyvinyl alcohol containing 4-nitro-4'-alkoxystilbene andphoto-crosslinkable cinnamyl groups as side chains has been synthesized. The in-situ simul-taneous photo-crosslinking poling of synthesized polymer films has been performed. Thesecond order nonlinear optical coefficient d_(33) of poled film is 11 pm/V. The SHG mea-surements show that the break-over temperature of SHG signal is raised obviously afterirradiation, its orientation stability is doubled as compared with that of non-crosslinkingsamples.     

重氮萘酮在环醚中热解反应研究

三种带有不同取代基的重氮萘酮(la～1c)在THF和二氧六环中加热分解给出不同的产物。1-重氮-4-萘酮(1a)的热解产物主要是重氮萘酮热解后产生的烯酮卡宾(2a)与环醚开环后形成的聚合物;3-甲基-1-重氮-4-萘酮(1b)的热解产物比较复杂,除冠醚类产物之外,还有烯酮卡宾对四氢呋喃和二氧六环的C-H键的插入反应产物、螺环化合物、2-甲基萘酚以及难以分离的聚合物;3-硝基-1-重氮-4-萘酮(1c)的热解产物主要是聚合物,此外还有少量C－H键的插入反应产物和2-硝基萘酚。对重氮萘酮热解反应的机理作了讨论。     

UV-Vis, NMR, and time-resolved spectroscopy analysis of photoisomerization behavior of three- and six-azobenzene-bound tris(bipyridine)cobalt complexes

The photoisomerization properties of tris(bipyridine)cobalt complexes containing six or three azobenzene moieties, namely, [Co(II)(dmAB)3](BF4)2 [dmAB = 4,4'-bis[3'-(4'-tolylazo)phenyl]-2,2'-bipyridine], [Co(III)(dmAB)3](BF4)3, [Co(II)(mAB)3](BF4)2 [mAB = 4-[3' '-(4' '-tolylazo)phenyl]-2,2'-bipyridine], and [Co(III)(dmAB)3](BF4)3, derived from the effect of gathering azobenzenes in one molecule and the effect of the cobalt(II) or cobalt(III) ion were investigated using UV-vis absorption spectroscopy, femtosecond transient spectroscopy, and 1H NMR spectroscopy. In the photostationary state of these four complexes, nearly 50% of the trans-azobenzene moieties of the Co(II) complexes were converted to the cis isomer, and nearly 10% of the trans-azobenzene moieties of the Co(III) complexes isomerized to the cis isomer, implying that the cis isomer ratio in the photostationary state upon irradiation at 365 nm is controlled not by the number of azobenzene moieties in one molecule but rather by the oxidation state of the cobalt ions. The femtosecond transient absorption spectra of the ligands and the complexes suggested that the photoexcited states of the azobenzene moieties in the Co(III) complexes were strongly deactivated by electron transfer from the azobenzene moiety to the cobalt center to form an azobenzene radical cation and a Co(II) center. The cooperation among the photochemical structural changes of six azobenzene moieties in [Co(II)(dmAB)3](BF4)2 was investigated with 1H NMR spectroscopy. The time-course change in the 1H NMR signals of the methyl protons indicated that each azobenzene moiety in [Co(II)(dmAB)3](BF4)2 isomerized to a cis isomer with a random probability of 50% and without interactions among the azobenzene moieties.     

Nitration of 2- and 4-[2-(2-furyl)vinyl]thiazole derivatives

Nitration of 4-methyl-2-[2-(nitro-2-furyl)vinyl]thiazole with a mixture of concentrated nitric and sulfuric acids leads to 4-methyl-5-nitro-2-[2-(3,5-dinitro-2-furyl)vinyl]thiazole. Under the same conditions 2-methyl- and 2-acetamido-4-[1-R-2-(5-nitro-2-furyl)vinyl]thiazoles (R=CH₃, Cl) are nitrated in the 3 position of the furan ring, 2-amino-4-[1-chloro-2-(5-nitro-2-furyl)vinyl]thiazole is nitrated in the 5 position of the thiazole ring and 2-acetamido-5-nitro-4-[2-(2-furyl)vinyl]thiazole undergoes profound changes. Under the influence of a mixture of of nitric acid and acetic anhydride the latter compound is converted quantitatively to the 5-nitro derivative (with respect to the furan ring), whereas 4-[2-(5-nitro-2-furyl)vinyl]thiazole derivatives do not undergo reaction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 314–317, March, 1977.     

Thermally stable nonlinear optical polyurea functionalized by multiple charge‐transfer chromophore

A novel high glass‐transition temperature (272 °C) polyurea functionalized by a multiple charge‐transfer chromophore, 2‐{4‐[4,5‐bis(4‐nitrophenyl)imidazolyl]phenyl}‐4,5‐bis(4‐aminophenyl)imidazole, was synthesized. Simultaneous poling and polymerization and the in situ second‐harmonic generation (SHG) measurement technique was carried out to evaluate the thermal stability of the poling‐induced orientation. The nonlinear optical coefficient d₃₃ of poled polyurea film was 24 pm/V at 1064 nm fundamental wavelength. The SHG signal of the poled polymer film was quite stable below 200 °C and still remained 80% of its initial value after heating at 250 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4297–4301, 2002     

PET表面接枝偶氮聚合物和光致取向研究

合成了一种丙烯酸酯类含芳香族偶氮生色团的单体ANB .以二苯甲酮为引发剂 ,采用固相紫外光接枝方法将上述单体接枝到聚酯 (PET)膜的表面 ,得到了一种具有光响应性的接枝膜 .通过SEM研究了接枝膜的表面和断面的形貌 ,观察到偶氮接枝层均匀地覆盖了PET表面 ,接枝层厚度约 0 4μm .研究发现 ,当使用488nm的线偏振激光照射接枝膜时 ,偶氮生色团通过快速的顺反异构化反应在垂直于偏振光极化方向上发生取向 ,得到了具有光学各向异性表面的PET接枝膜 .接枝膜的取向是一个快速过程 ,取向有序度参数在 2min时即达到最大值 ,为 0 0 6左右     

Enhanced thermal stability of dipole alignment in inorganic-organic hybrid films containing benzothiazole chromophore

A new thermally stable second-order nonlinear optical (NLO) inorganic-organic hybrid film was successfully prepared by using a sol-gel process of alkoxysilane dye containing a benzothiazole unit. The dye-bonded precursor was synthesized from 3-isocyanatopropyltriethoxysilane and the heterocycle azo dye 2-[4'-(N-ethyl-N-2-hydroxyethyl)-amino-phenylazo]-6-nitrobenzothiazole (EHNBT) via a urethane reaction. Molecular structural characterization for the resultant was achieved by elemental analysis, FTIR, UV-visible spectra, and 1H NMR. The second harmonic coefficients (d33) of poled hybrid films measured by a Maker fringe technique were in the range 15.9-72.1 pm/V at a wavelength of 1064 nm, depending on the concentration of alkoxysilane dye. The hybrid films containing the benzothiazole moiety exhibited higher thermal stability of dipole alignment at elevated temperatures than their analogues with a benzene ring. The d33 value of the poled film remained at 94% of its initial value after heating at 120 degrees C for 6 h, and only 18% decayed in 15 min at 180 degrees C. The result indicates that the hybrid film is suitable for the fabrication of an electro-optic device.     

Synthesis and characterization of photocrosslinkable,side‐chain,second‐order nonlinear optical poly(ester imide)s with great film‐forming ability and long‐term dipole orientation stability

A series of photocrosslinkable, side‐chain, second‐order nonlinear optical (NLO) poly(ester imide)s (PEIs) based on a chromophore‐containing dianhydride, 2,2′‐{4‐[(4‐nitrophenyl)‐azo]phenyl}iminobis(ethyl benzene‐1,2‐dicarboxylic acid anhydride‐4‐carboxylate), benzophenone‐3,3′,4,4′‐tetracarboxylic dianhydride, and 4,4′‐diamino‐3,3′‐dimethyl diphenylmethane were prepared. The resulting PEIs exhibited many useful physical characteristics, such as good organosolubility, excellent film‐forming properties, high glass‐transition temperatures (186–229 °C), and high thermal decomposition temperatures. The electrooptic coefficient value of PEI3 at 650 nm was 11.5 pm/V, and high long‐term stability of the NLO chromophore alignment in the poled PEI3 film at 120 °C was observed. The temporal stability of the dipole orientation at 150 °C was further enhanced by ultraviolet irradiation because of photocrosslinking. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 303–312, 2003     

Photoinduced alignment of azobenzene side‐chain polymers with short spacer: Biaxial orientation and fast response

Side‐chain azobenzene‐containing liquid crystalline polymer (ALCP) of Poly(6‐[4‐(4‐cyanophenylazo)phenoxy] x‐methylene methacrylate)(Px, x is 2 or 6) was synthesized and used to study its photoinduced alignment behavior irradiated by a linearly polarized laser at room temperature. The relationships between transmittance and irradiation time as well as transmittance and various incident angles were studied in detail. The oversaturation phenomenon of P ₂ film was found to be higher than 1 mW/cm² under irradiation energy density. A model of the biaxial orientation was introduced to explain the phenomenon: it is the rigid short spacer that makes it possible for mesogen to coexist in a way of out‐of‐plane and in‐plane orientation (biaxial orientation), in which the type of photoinduced motions is a single mesogen motion in the film of P ₂ , whereas in the film of P ₆ with longer spacer, the motion is a microdomain motion. The whole domain motion restricted the out‐of‐plane orientation, which shows a slow orientation rate and all mesogens aligned within the film plane. A novel dynamic fitting was also presented to describe the orientation of P ₂ , which was discussed in terms of the fitting parameters. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1378–1384, 2006     

侧链型偶氮聚合物液晶在不同温度条件下的光致取向

在高于和低于玻璃化转变温度 (Tg)的温度范围内 ,研究了聚甲基丙烯酸 ( 6 [4 ( 4 氰基偶氮苯 )苯氧基 ]己酯 ) (Poly( 6 [4 ( 4 cyanophenylazo)phenoxy]hexylmethacrylate) (PM6ABCN) )聚合物膜的光致取向行为 .实验结果表明 ,在温度低于Tg 时 ,实验温度对取向速率没有影响 ;高于Tg 温度时 ,取向的速率随温度升高而变大 ,取向过程的表观活化能为 3 2 76kJ mol.通过对Tg 温度以下的光致取向进行分析 ,对光致取向过程提出了一个新的微相模型 ,微相内的温度能够达到Tg 以上 ,而实验中控制的样品宏观温度不变 ;高于Tg 温度时的光致取向过程受到宏观温度的控制 ,其表观活化能远远小于热致的各向同性相I(Isotropicphase,I)到向列相N(Nematicphase,N)相转变表观活化能 ( 3 40 2kJ mol) ,表明光致取向过程对温度的依赖性较小     

Supramolecular architecture in Langmuir and Langmuir-Blodgett films incorporating a chiral azobenzene

This article describes the synthesis and fabrication of Langmuir and Langmuir-Blodgett (LB) films incorporating a chiral azobenzene derivative, namely, ( S)-4- sec-butyloxy-4'-[5'-(methyloxycarbonyl)pentyl-1'-oxy]azobenzene, abbreviated as AZO-C4(S). Appropriate conditions for the fabrication of monolayers of AZO-C4(S) at the air-water interface have been established, and the resulting Langmuir films have been characterized by a combination of surface pressure and surface potential versus area per molecule isotherms, Brewster angle microscopy, and UV-vis reflection spectroscopy. The results indicate the formation of an ordered trilayer at the air-water interface with UV-vis reflection spectroscopy showing a new supramolecular architecture for multilayered films as well as the formation of J aggregates. Films were transferred onto solid substrates, with AFM revealing well-ordered multilayered films without 3D defects. Infrared and UV-vis absorption spectroscopy indicate that the supramolecular architecture may be favored by the formation of H bonds between acid groups in neighboring layers and pi-pi intermolecular interactions. Circular dichroism spectra reveal chiro-optical activity in multilayered LB films.     

Synthesis and properties of two new liquid crystals: an analytical and thermodynamic study

Synthesis, analytical performances, thermodynamic and surface properties of two new liquid crystals substituted with poly(ethylene oxide) chains are described. The first of them is N,N'-diphenyl-[4-[2,3,4-tri[2-(2-metoxyethoxy)ethoxy]benzylidene]i mine]piperidine (LC1) and the second is 2-hydroxy-3-methyl-4-[4-[2-(2-butoxyethoxy)ethoxy]] 4'-[4-[2-(2-butoxyethoxy)ethoxy]styryl]azobenzene (LC2). The nematic ranges of the two liquid crystals, determined by differential scanning calorimetry do not interfere. The analytical and thermodynamic studies of LC1 and LC2 in the solid, nematic and liquid state were done using a series of appropriate solutes. Comparison of the analytical performances shows a better efficiency in the nematic state.     

OPTICAL STORAGE MECHANISM AND HIGH-ORDER DIFFRACTION PROPERTIES OF NITROAZOBENZENE-CONTAINING POLYESTER FILMS

Using Nd:YAG second harmonic pulse (100 ps), the optical storage proper-ties of two novel polyesters, poly [4'-bis (N, N-oxyethylene) imino-4-nitroazobenzene suc-cinyl] and poly [2'-chloro-4'-bis (N, N-oxyethylene) iminth-4-nitroazobenzene succiny] havebeen studied by multiwave mixing. The high-order diffractions of the orientation gratingsinduced by anisotropy via the reorientation of nitroazobenzene groups and optical infor-mation storage with long-term stability have been realized by multiwave mixing in theirfilms. Up to 3rd order forward diffraction was detected in two wave mixing, while up to 4thorder backward diffraction was observed in degenerated four wave mixing. The recordingmechanism was explained by the trans-cis-trans isomerization cycles of azobenzene groups.The isomerization of these azobenzene groups probably undergoes with inversion mecha-nism under the experimental conditions. The information recorded in these films has beenkept for more than 6 months.     

Supramolecular chirality from an achiral azobenzene derivative through the interfacial assembly: effect of the configuration of azobenzene unit

The Langmuir-Schaefer (LS) films of an achiral azobenzene derivative, 4-octyl-4'-(5-carboxypentamethyleneoxy) azobenzene (C8AzoC5), were fabricated and their optical activities were investigated. It was found that the LS film of the trans-C8AzoC5 showed strong Cotton effect, while that of cis-C8AzoC5 did not. The characterization of the LS films by UV-vis, Fourier transform infrared (FT-IR) spectra, and X-ray diffraction (XRD) revealed that this interesting phenomenon was due to the different packing of the azobenzene unit in the LS film. The planar conjugated trans-azobenzene favored ordered cooperative packing in a helical sense and produced the supramolecular chirality, while the cis-isomer did not due to the bulky twisted configuration.     

Circularly Polarized Absorption Property of Tetra-4[4''''-(2-methylbutoxy)benzoyloxy]phenyl Porphyrin by Introducing Optical Pendant Groups

Circularly polarized luminescent(CPL) materials possess special dissymmetric optical property, i.e. luminescent light having different intensities for left (L) and right(R) circularly polarized components. Recently, these materials have been applied in colour-image projection, stereoscopic displays and light-emitting diodes(LEDS)1-7. We have synthesized a new porphyrin derivative, tetra-4[4'-(2-methylbutoxy)benzoyloxy] phenyl porphyrin [T(MBBP)P], by introducing a chiral group, which p…     

Nitro derivatives of 2-(1-naphthyl) thiophene

2-[1-(3, 4-Dihydronaphythyl)]thiophene, 2-(1-naphthyl)thiophene, 3, 4, 5-triacetoxymercuri-, 3, 4-diacetoxymercuri-5-nitro-, 4, 5-diacetoxymercuri-3-nitro-2-(1-naphthyl)thiophenes and 3, 3, 4-triacetoxymercuri-2[1-(4-nitronaphthyl)]thiophene are synthesized and characterized. Nitration of 2-(1-naphthyl)thiophene with copper nitrate in acetic anhydride leads to formation of two isomeric mono-nitro derivatives, 4-nitro- and 5-nitro-2-(1-naphthyl)thiophene.     

New syntheses of [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 4,6-dioxide

New methods were developed for the synthesis of [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 4,6-dioxide from 4-(tert-butyl-NNO-azoxy)-N-nitro-1,2,5-oxadiazol-3-amine or its alkali metal salts and acid anhydrides (or chlorides) in the presence of strong acids. The yield of [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 4,6-dioxide in acetic anhydride in the presence of sulfuric acid or sulfuric anhydride at 20°C in 20 min attained 83%. A general mechanism was proposed for the reactions under study. Acetyl group behaved for the first time as departing group in the synthesis 1,2,3,4-tetrazine 1,3-dioxides, and [1,2,5]oxadiazolo[3,4-e][1,2,3,4]tetrazine 4,6-dioxide was obtained in 47% yield from N-[4-(acetyl-NNO-azoxy)-1,2,5-oxadiazol-3-yl]acetamide.     

Polymers derived from N‐isopropylacrylamide and azobenzene‐containing acrylamides: Photoresponsive affinity to water

N‐Isopropylacryamide was copolymerized by free‐radical polymerization with N‐[2‐(4‐phenylazophenoxy)ethyl]acrylamide derivatives that were substituted at their 4′‐position with ethoxy, methoxyethoxy, or isopropyl units, or with N‐{2‐[4‐(pyridin‐2‐ylazo)phenoxy]ethyl}acrylamide. The polymers were soluble in cold water and possessed lower critical solution temperatures (LCSTs). The value of the LCST rose a few degrees after UV irradiation and dropped after irradiation with visible light, reversibly, in processes that corresponded to the isomerization of the azobenzene units. The polymers became increasingly hydrophobic after increasing their azobenzene content. The difference of hydrophobicity correlates with the absorption band height at about 400 nm. The structure of the substituent on the azobenzene unit affected both the transition temperature and the hydrophobicity. A change in photoinduced wettability for water was observed to occur on a prepared film at a temperature different from the LCST determined in water. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5200–5214, 2004     

Synthesis and characterization of thermally crosslinked polyimide with second-order nonlinear optical chromophore

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