Molecular design,synthesis, and nonlinear optical properties of novel T‐type polyimides with exceptionally high thermal stability of the second harmonic generation

2,5‐Bis‐(3,4‐dicarboxyphenylcarboxyethoxy)‐4′‐nitrostilbene dianhydride was prepared and reacted with 1,4‐phenylenediamine, 4,4′‐oxydianiline, 4,4′‐diaminobenzanilide, and 4,4′‐(hexafluoroisopropylidene)dianiline to yield unprecedented novel T‐type polyimides ( 4 – 7 ) containing 2,5‐dioxynitrostilbenyl groups as nonlinear optical chromophores, which constituted parts of the polymer backbones. 4 – 7 were soluble in polar solvents such as acetone and N,N‐dimethylformamide. They showed thermal stability up to 300 °C in thermogravimetric analysis thermograms; the glass‐transition temperatures obtained from differential scanning calorimetry thermograms were around 153 °C. The second harmonic generation (SHG) coefficients (d₃₃) of poled polymer films at the 1064‐cm^?1 fundamental wavelength were around 4.35 × 10^?9 esu. The dipole alignment exhibited exceptionally high thermal stability even at 45 °C higher than the glass‐transition temperature, and there was no SHG decay below 200 °C because of the partial main‐chain character of the polymer structure, which was acceptable for nonlinear optical device applications. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3189–3199, 2004     

Synthesis and nonlinear optical properties of novel Y‐type polyurethane containing tricyanovinylthiazole with enhanced thermal stability of second harmonic generation

A novel Y‐type poly[iminocarbonyloxyethyl‐5‐methyl‐4‐{2‐thiazolylazo‐4‐(1,2,2‐tricyanovinyl)}resorcinoxyethyloxycarbonylimino‐(3,3′‐dimethoxy‐4,4′‐biphenylene)] 4 containing 5‐methyl‐4‐{5‐(1,2,2‐tricyanovinyl)‐2‐thiazolylazo}resorcinoxy groups as nonlinear optical (NLO) chromophores, which constitute part of the polymer backbone, was prepared and characterized. Polyurethane 4 is soluble in common organic solvents such as acetone and N,N‐dimethylformamide. It showed a thermal stability up to 250 °C in thermogravimetric analysis thermogram and the glass‐transition temperature (T_g) obtained from differential scanning calorimetry thermogram was around 118 °C. The second harmonic generation coefficient (d₃₃) of poled polymer films at 1560 nm fundamental wavelength was around 8.43 × 10^?9 esu. The dipole alignment exhibited a thermal stability even at 12 °C higher than T_g, and there was no SHG decay below 130 °C due to the partial main‐chain character of the polymer structure, which is acceptable for NLO device applications. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1166–1172, 2010     

Molecular design,synthesis, and properties of Y‐type nonlinear optical polyester containing tricyanovinylthiophene with enhanced thermal stability of second harmonic generation

1‐{3,4‐Di‐(2‐hydroxyethoxy)phenyl}‐2‐(2‐thiophenyl)ethene (5) was prepared and condensed with terephthaloyl chloride to yield polyester (6). Polymer 6 was reacted with tetracyanoethylene to give a new Y‐type polyester (7) containing 1‐(3,4‐dioxyethoxy)phenyl‐2‐{5‐(2,2,3‐tricyanovinyl)‐2‐thiophenyl)}ethenyl groups as NLO‐chromophores, which are components of the polymer backbones. Polyester 7 is soluble in common organic solvents such as N,N‐dimethylformamide and acetone. Polymer 7 showed a thermal stability up to 300 °C in thermogravimetric analysis with glass transition temperature (T_g) obtained from differential scanning calorimetry near 126 °C. The second harmonic generation (SHG) coefficient (d₃₃) of poled polymer film at the 1560 nm fundamental wavelength was around 6.57 × 10^?9 esu. The dipole alignment exhibited high thermal stability up to the T_g, and there was no SHG decay below 125 °C due to the partial main‐chain character of polymer structure, which is acceptable for NLO device applications. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1911–1919, 2009     

Preparation and nonlinear optical properties of novel Y-type polyesters with highly enhanced thermal stability of second harmonic generation

3,4-Di-(2′-hydroxyethoxy)benzylidenemalononitrile (3) was prepared and condensed with terephthaloyl chloride and adipoyl chloride to yield novel Y-type polyesters (4-5) containing 3,4-dioxybenzylidenemalononitrile groups as NLO-chromophores, which constituted parts of the polymer main-chains. The resulting polymers 4-5 are soluble in common organic solvents such as acetone and N,N-dimethylformamide. They showed thermal stability up to 300 °C in thermogravimetric analysis with glass-transition temperatures obtained from differential scanning calorimetry in the range 89-91 °C. The second harmonic generation (SHG) coefficients (d₃₃) of poled polymer films at the 1064 nm fundamental wavelength were around 2.47 pm/V. The dipole alignment exhibited high thermal stability even at 10 °C higher than T_g, and there is no SHG decay below 100 °C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.     

Synthesis and nonlinear optical properties of novel Y‐type polyester containing tricyanovinylthiazolylazoresorcinoxy group with enhanced thermal stability of dipole alignment

Novel Y‐type polyester 4 containing 5‐methyl‐4‐{5‐(1,2,2‐tricyanovinyl)‐2‐thiazolylazo}resorcinoxy groups as nonlinear optical (NLO) chromophores, which are parts of the polymer backbone, was prepared, and its NLO properties were investigated. Polyester 4 is soluble in common organic solvents such as N,N‐dimethylformamide and dimethylsulfoxide. Polymer 4 shows a thermal stability up to 250 °C from thermogravimetric analysis with glass‐transition temperature obtained from differential scanning calorimetry of approximately 94 °C. The second harmonic generation (SHG) coefficient (d₃₃) of poled polymer film at 1560‐nm fundamental wavelength is 8.12 × 10^?9 esu. The dipole alignment exhibits a thermal stability even at 6 °C higher than glass‐transition temperature (T_g), and no significant SHG decay is observed below 100 °C due to the partial main‐chain character of polymer structure, which is acceptable for NLO device applications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

The design,synthesis, and nonlinear optical properties of novel X‐type polyurethane containing dicyanovinylnitroresorcinoxy group with enhanced SHG thermal stability

Novel X‐type polyurethane 5 containing 4‐(2′,2′‐dicyanovinyl)‐6‐nitroresorcinoxy groups as nonlinear optical (NLO) chromophores, which constitute parts of the polymer backbone, was prepared and characterized. Polyurethane 5 is soluble in common organic solvents such as acetone and N,N‐dimethylformamide. It shows thermal stability up to 280 °C from thermogravimetric analysis with a glass transition temperature (T_g) obtained from differential scanning calorimetry thermogram of around 120 °C. The second harmonic generation (SHG) coefficient (d₃₃) of poled polymer film at 1064‐nm fundamental wavelength is around 6.12 × 10^?9 esu. The dipole alignment exhibits a thermal stability even at 5 °C higher than T_g, and there was no SHG decay below 125 °C due to the partial main chain character of the polymer structure, which is acceptable for NLO device applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis and nonlinear optical properties of novel Y-type polyimides with enhanced thermal stability of dipole alignment

2,3-Bis-(3,4-dicarboxyphenylcarboxyethoxy)-4′-nitrostilbene dianhydride (4) was prepared and reacted with 1,4-phenylenediamine, 4,4′-oxydianiline, 4,4′-diaminobenzanilide and 4,4′-(hexafluoroisopropylidene)dianiline to yield novel polyimides 5-8 containing 2,3-dioxynitrostilbenyl groups as NLO-chromophores, which constituted parts of the polymer backbones. The resulting polyimides 5-8 were soluble in polar solvents such as acetone and DMF. Polymers 5-8 showed a thermal stability up to 300 °C in TGA thermograms with T_g values obtained from DSC thermograms in the range of 135-160 °C. The SHG coefficients (d₃₃) of poled polymer films at the 1064 cm⁻¹ fundamental wavelength were around 5.26 × 10⁻⁹ esu. The dipole alignment exhibited exceptionally high thermal stability even at 30 °C higher than T_g and there was no SHG decay below 170-190 °C due to the partial main chain character of polymer structure, which was acceptable for NLO device applications.     

Synthesis and electro‐optic properties of novel X‐type polyurethane containing nitrophenylazonitroresorcinoxy group with highly enhanced thermal stability of dipole alignment

Novel X‐type polyurethane 4 containing 4‐(4‐nitrophenylazo)‐6‐nitroresorcinoxy groups as nonlinear optical (NLO) chromophores, which are parts of the polymer main chains, was prepared and characterized. Polyurethane 4 is soluble in common organic solvents such as acetone and N,N‐dimethylformamide. It shows thermal stabilities up to 270 °C from thermogravimetric analysis with glass transition temperature obtained from differential scanning calorimetry of about 134 °C. The second harmonic generation (SHG) coefficient (d₃₃) of poled polymer film at 1064 nm fundamental wavelength is 5.37 × 10^?9 esu. Polymer 4 exhibits a thermal stability up to T_g, and no significant SHG decay is observed below 135 °C, which is acceptable for NLO device applications. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 760–766     

Synthesis and characterization of Y‐type polymers for second‐order nonlinear optical applications

A series of dicyanomethylene‐substituted polymers having Y‐type molecular architecture were synthesized by Knoevenagel condensation reaction. The polymers were found to be soluble in organic solvents like tetrahydrofuran and chloroform. From gel permeation chromatography, the molecular weights of the polymers were found to be in the range of 15,300–33,800 g/mol. Thermal analysis showed that the polymers were stable up to 350 °C with glass transition temperature (T_g) in the range of 129–212 °C. These polymers were found to form good optical quality films. The order parameter was calculated to be in the range of 0.01–0.48. Atomic force microscopy indicated prominent morphology changes due to alignment of dipoles after poling. By using Nd:YAG laser of 1064 nm, angular dependence and temperature dependence of second‐harmonic generation intensity were investigated. The geometry optimization, shape of polymers, and restricted torsion angle between acceptor and donor substituents (push–pull system) were calculated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Synthesis and characterization of interpenetrating polymer networks with nonlinear optical properties

We report the synthesis and characterization of interpenetrating polymer networks (IPNs) exhibiting nonlinear optical (NLO) properties. The network consists of aliphatic polycarbonate urethane (PCU) and poly(methyl methacrylate-co-N,N-disubstituted urea), with a nonlinear optical (NLO) chromophore incorporated into N,N-disubstituted urea. The full IPNs have only one T_g, as determined by differential scanning calorimetry (DSC), together with scanning electron microscopy (SEM) observations, suggest a single phase morphology. The thin films of IPNs are transparent and the unpoled samples produced second harmonic generation (SHG) signals at room temperature. This result indicates that the NLO chromophore is oriented noncentrosymmetrically during the IPN formation process and is tightly held between the permanent entanglements of the two component networks of the IPN. © 1996 John Wiley & Sons, Inc.     

Molecular design, synthesis and electro-optic properties of novel Y-type polyurethanes with high thermal stability of second harmonic generation

2,4-Di-2^′-hydroxyethoxy)benzylidenemalononitrile (3) was prepared and condensed with 2,4-toluenediisocyanate and 3,3^′-dimethoxy-4,4^′-biphenylenediisocyanate to yield unprecedented novel Y-type polyurethanes (4-5) containing 2,4-dioxybenzylidenemalononitrile group as a nonlinear optical (NLO) chromophore, which constitutes a part of the polymer backbone. The resulting polyurethanes 4-5 were soluble in common organic solvents such as acetone and DMF. Polymers 4-5 showed a thermal stability up to 260 °C from thermogravimetric analysis (TGA) with differential scanning calorimetry (DSC) giving T_g values around 143-156 °C. The approximate lengths of aligned NLO-chromophores estimated from AFM images of poled polymer films were about 10 nm. The SHG coefficients (d₃₃) of poled polymer films were around 7.4 × 10⁻⁹ esu. These Poled polymers exhibited a greater thermal stability of dipole alignment even at 10 °C higher than T_g, and no SHG decay was observed below 155 °C due to the partial main chain character of the polymer structure and extensive hydrogen bonds between urethane linkage, which is acceptable for NLO device applications.     

Synthesis of chromophores and polyimides with a green chemistry approach for second‐order nonlinear optical applications

This article presents the synthesis of nonlinear optical responsive chromophores by adopting a green chemistry approach by coupling N‐methyl‐N‐(2‐hydroxyethyl)‐4‐amino benzaldehyde with barbituric acid, 1,3‐indanedione, and 1,3‐diethyl‐2‐thiobarbituric acid as the acceptors through stilbene linkage. We performed the synthesis in less than 10 minutes at room temperature with water as a solvent without catalyst. Two different side‐chain polyimides were synthesized from poly(hydroxy‐imide)s with chromophores by Mitsunobu reaction. The chromophores were characterized by Fourier transform infrared, ¹H NMR, ¹³C NMR, and elemental analysis. However, the polyimides were characterized by Fourier transform infrared and ¹H NMR. The inherent viscosities (η_inh) of polyimides were determined by Ubbelohde viscometer, which ranged between 0.1793 and 0.1890 dL/g. The molecular weights of the polyimides were determined using gel permeation chromatography and were in range of 23 000 to 26 000. Polyimides demonstrated an excellent solubility in polar aprotic solvents, indicating good processability. Thermal behavior of these polyimides was studied by differential scanning calorimetry and thermogravimetric analysis. The T_g's were in the range of 185°C to 255°C. The change in the molecular orientation in the polymer films after electrical poling was ascertained using ultraviolet‐visible spectrophotometer and atomic force microscopy. The thicknesses and refractive indices of the thin films were determined by an ellipsometer. The second harmonic generation coefficients of the corona‐poled polymer films at T_opt's, determined by the Maker fringe technique, ranged between 59.33 and 77.82 pm/V. High thermal endurance observed for the polyimides is attributed to the extensive hydrogen bonds in the matrix. The developed polyimides showed no decay in second harmonic generation signals below 110°C, indicating the acceptance for nonlinear optical devices.     

Synthesis and properties of novel polyurethanes containing 3,4‐dioxybenzylidenecyanoacetate group as a nonlinear optical chromophore

Methyl 3,4‐di‐(2′‐hydroxyethoxy)benzylidenecyanoacetate ( 3 ) was prepared by hydrolysis of methyl 3,4‐di‐(2′‐vinyloxyethoxy)benzylidenecyanoacetate ( 2 ). Diol 3 was condensed with 2,4‐toluenediisocyanate, 3,3′‐dimethoxy‐4,4′‐biphenylenediisocyanate, and 1,6‐hexamethylenediisocyanate to yield polyurethanes 4 – 6 containing the nonlinear optical chromophore 3,4‐dioxybenzylidenecyanoacetate. The resulting polyurethanes 4 – 6 were soluble in common organic solvents such as acetone and dimethylformamide. Polymers 4 – 6 indicated thermal stability up to 300 °C in thermogravimetric thermograms with glass‐transition temperature values obtained from differential scanning calorimetric thermograms in the range of 78–102 °C. The second‐harmonic generation coefficients (d₃₃) of the poled polymer films were around 6.9 × 10^?9 esu. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1742–1748, 2002     

Interaction between nitric oxide and lipid-like DDPA LB film investigated with SHG and AFM

Interactions between Nitric oxide (NO) and DDPA Langmuir-Blodgett (LB) film are investigated with second harmonic generation (SHG) and atomic force microscopy (AFM). It has been found that the adsorption of NO molecules on DDPA LB film only changes the value of the second-order susceptibility of the DDPA molecule on film but not its orientation.     

Characterization of a side chain polymer for second‐order nonlinear optical properties

We report the characterization of copolymers of methyl methacrylate (MMA) and 2‐propenoic acid, 2‐methyl‐, 2‐[[[[4‐methyl‐3‐[[(2‐methyl‐4‐nitrophenyl)amino]carbonyl]aminophenyl]carbonyl]oxy]ethyl ester (PAMEE) exhibiting nonlinear optical (NLO) properties. The linear copolymer, poly(MMA‐co‐PAMEE), with a NLO chromophore incorporated into PAMME exhibits a high glass transition temperature of 131°C, as determined by DSC. The thin films of copolymers, which were cast on microscopic glass slides, were optically transparent, and the corona poled polymers produced relatively large and stable second harmonic generation (SHG) signals at room temperature. The nonlinear coefficient d₃₃ of the crosslinked copolymer containing 30 wt % PAMEE was 30.8 pm/V. The SHG signal strength remained unchanged, even after 120 days, and exhibited excellent thermal stability at 65°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1245–1254, 1999     

Stable second‐order NLO semi‐IPN system based on bipyridine‐containing polyimide and alkoxysilane dye

An organosoluble polyimide based on bipyridyl moiety and an alkoxysilane dye have been developed for second‐order non‐linear optics (NLOs). This bipyridine‐containing polyimide exhibits a glass transition temperature of 254°C and a degradation temperature of 400°C. An NLO‐active semi‐interpenetrating network (IPN) system was prepared by blending the polyimide with the alkoxysilane dye via in situ sol‐gel process of alkoxysilane. The selection of this bipyridine‐containing polyimide as the polymeric matrices provides improved solubility and thermal stability, and most importantly enhanced intermolecular interactions. No aggregation of the NLO chromophores in the polyimide matrices was observed through morphology and NLO studies. Under the limitation of chromophore degradation at elevated temperatures, the pristine poled/cured alkoxysilane dye exhibits poorer long‐term stability. By introducing the polyimide upon a silica network by the semi‐IPN system, randomization of the oriented chromophores can be effectively suppressed. Using in situ contact poling, the r₃₃ coefficients of 2.2–17.0 pm/V were obtained for the optically clear semi‐IPN NLO materials. Excellent temporal stability (100°C) was also achieved for these semi‐IPN materials. Copyright © 2005 John Wiley & Sons, Ltd.     

Morphology, crystalline structure and thermal properties of PEO/MEEP blends

Poly(ethylene oxide) and poly[bis[2-(2′-methoxyethoxy) ethoxy] phosphazene], PEO/MEEP, polymer blends were investigated by thermal analysis, X-ray diffraction, and atomic force microscopy. MEEP is an amorphous polymer and its semicrystalline blends with PEO showed two distinct glass transitions, whose composition dependence was analysed by the Lodge and McLeish self-concentration model. It appears that an amorphous miscible phase is present in these blends. Excess melting enthalpy was observed for blends with high MEEP concentration. PEO lamellar characteristics exhibited changes as a function of MEEP content, both in X-ray patterns and AFM images that indicated the intercalation of MEEP side chains in the lamellar crystalline structure.     

Intramolecular branching distributions in metallocene short‐chain branched polyethylenes examined by crystallization and annealing at high pressure

Uniform branched polyethylenes produced by metallocene catalysts can be subjected to a limited degree of intramolecular fractionation by crystallization or annealing at pressures of 495 MPa. Longer stem lengths in lamellae are more achievable by this process than by treatments at atmospheric pressure. Although the intervention of the hexagonal phase allows greater lamellar stem lengths to be achieved, the small proportion of longer methylene sequence lengths in the melt imposes limitations on the degree of isothermal thickening achievable. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1986–1996, 2005     

Synthesis of novel poly(meth)acrylates containing tetracyanocyclopropyl groups as piezoelectric chromophores and their properties

p‐(2,2,3,3‐Tetracyanocyclopropyl)phenoxyethyl acrylate ( 5a ) and p‐(2,2,3‐tetracyanocyclopropyl)phenoxyethyl methacrylate ( 5b ) were prepared by the reactions of bromomalononitrile with p‐(2‐acryloyloxyethoxy)benzylidenemalononitrile and p‐(2‐methacryloyloxyethoxy)benzylidenemalononitrile, respectively. Monomers 5a and 5b were polymerized with free‐radical initiators to obtain polymers with multicyanocyclopropane functionalities in the pendant group. The resulting polymers were soluble in acetone, and the inherent viscosities were 0.25–0.30 dL/g. Solution‐cast films showed thermal stability up to 300 °C with glass‐transition temperatures of 140–156 °C. The dipole moments of 5a and 5b , calculated by the atom superposition and electron delocalization molecular orbital method, were 7.58–7.30 D. Piezoelectric coefficients (d₃₁) of the poled polymer films were 1.8–1.9 pC/N, acceptable values for piezoelectric device applications. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 379–384, 2002     

Annealing behavior of gel‐spun polyethylene fibers at temperatures lower than needed for significant shrinkage

The annealing at 373 K of ultrastrong, gel‐spun polyethylene (PE) has been studied. At this temperature, the fibers show no significant shrinkage. Still, a significant decrease in the mechanical properties is observed. The fibers have been analyzed with differential scanning calorimetry (DSC), temperature‐modulated differential scanning calorimetry (TMDSC), atomic force microscopy (AFM), and small‐angle X‐ray scattering (SAXS). During the annealing, the glass transition of the intermediate phase is exceeded, as shown by DSC. When split for structure analysis by AFM, the annealed fibers undergo plastic deformation around the base fibrils instead of brittle fracture. The quasi‐isothermal TMDSC experiments are compared to the minor structural changes seen with SAXS and AFM. The loss of performance of the PE fibers at 373 K is suggested to be caused by the oriented intermediate phase, and not by major changes in the structure or morphology. The overall metastable, semicrystalline structure is shown by TMDSC to posses local regions that can melt reversibly. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 403–417, 2003