Effects of Chromophore Functionalization and Physical Aging during Poling on Chromophore Orientational Dynamics in Poly(arylene ether)s for Second-Order Nonlinear Optics (original) (raw)
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Macromolecules, 1994
Rotational dynamics of nonlinear optical chromophores embedded in amorphous polymer films were studied using second harmonic generation. Corona poling was used to orient the chromophores into the bulk noncentrosymmetric structure required to observe second-order nonlinearity. Electric field effects were examined by simultaneously measuring the second harmonic signal (during and following poling) and surface voltage decay (following poling). It is found that for short times the residual field following poling retards chromophore reorientation. A mathematical model that describes the rotational Brownian motion of chromophores in a polymer matrix is developed to simulate the field-dependent behavior. The electric field effects can therefore be deconvoluted from the Brownian motion to reveal information concerning local mobility in polymers. Further applications of the model in distinguishing the post-poling electric field effects and in computing the local free volume and viscosity are discussed. A first attempt is made to realize the contributions of the residual surface voltage, field-induced bulk charges, and thermally injected charges to the rotational motion of the chromophores. The magnitude of the local free volume and the local viscositytemperature behavior in a doped poly(methy1 methacrylate) system are estimated and compared with those predicted by the Doolittle-Williams-Landel-Ferry equation.
1993
The all-optical recording of a microscopic second-order nonlinear susceptibility in a new azo dye pendant polyurethane polymer is investigated. An experimental configuration which permits self-phase matched was used. The peak value of the phase-matched lightinduced second order nonlinear optical susceptibility v (2) measured at 1.06 lm reaches 62 pm/V at room temperature, which corresponds to a molecular orientation ratio of 30%. Temporal stability of the induced polar order measured by second harmonic generation revealed a reduced decay rate of the v (2) value in comparison to Disperse Red 1 pendant poly(methyl methacrylate).
MRS Proceedings, 1997
A high-p 3 chromophore APII utilizing isophorone as n-conjugation bridge was processed into both PMMA guest host and crosslinked (XL) polyurethane network with various loading densities. High electro-optic coefficients, r3 3 = 30 pm/V (in PMMA) and r 33 = 32 pm/V (in polyurethane) at 1.06 pm were obtained. Alignment temporal stability ranged from 90 to 120"C for XL polymer network. There is virtually no intrinsic absorption loss at 1.3 pm (solution measurement). Also noteworthy is that high optimum loading densities of this chromophore are attainable in both cases without detectable chromophore aggregation due to intermolecular electrostatic interactions.
Polymer, 2002
Functionalised second-order nonlinear optical (NLO) polyimides have been developed. The key challenge in our approach was a one-step synthesis of these polymers, by reaction of di(hydroxyalkyl) chromophores and diimides utilising the Mitsunobu reaction. Glass transition temperatures in the range of 205±2248C were obtained. Thin spincoated ®lms of the polymers were corona-poled and analysed by secondharmonic generation; values for d 33 of 30 pm/V were obtained. Poled order stability measurements over periods of 210±500 h resulted in 70±90% of remaining NLO-response at 1258C. q
Polymer Journal, 1997
New second-order nonlinear optical main-chain polymers have been synthesized in very high yields by a two-stage Knoevenagel polycondensation from 3,6-diformyl-9-heptylcarbazole and bis(cyanoacetate)s. In these main-chain polymers, two kinds of nonlinear optical (NLO) chromophores, carbazole with two acceptor groups and 4'-nitrophenylazoaniline, were introduced in a slipped shoulder-to-shoulder arrangament. All polymers were determined to be amorphous and to have glass transition temperatures in the range of 134-l 58°C by a differential scanning calorimeter. The chloroform soluble main-chain polymers show very high weight and number average molecular weights measured by a gel permeation chromatography. Thin films of the polymers could be obtained by a spin coating method. The orientation of dipoles could be achieved by applying an electric field. These poled films show good reasonable and stable second-order nonlinear optical responses.
Polymers for Advanced Technologies, 2018
This article presents the synthesis of nonlinear optical responsive chromophores by adopting a green chemistry approach by coupling N-methyl-N-(2-hydroxyethyl)-4amino 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, 1 H NMR, 13 C NMR, and elemental analysis. However, the polyimides were characterized by Fourier transform infrared and 1 H 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 characterization of polymers for nonlinear optical applications
2003
A difunctional NLO Azo-Dye chromophore has been synthesized and polymerization has been performed with a comonomer bearing a side-chain epoxy group. Deposition of the polymer on glass substrates was performed by spin-coating, resulting in uniform films up to 2 μm thickness. The orientation of the chromophore was performed under a "pin-to-plane" positive corona discharge followed by a heat- treatment in order to obtain reticulation of the films. Molecular orientation has been investigated using UV-Vis. and Raman spectroscopy. Poling of the films results in a decay of absorbance as well as in a blue shift of the spectrum. At the same time, the 1600 cm-1 band disappears from the Raman spectra, indicating orientation of the chromophores. Cross-linking has been studied by FTIR and all-optical poling and showed an improved stability of the electro-optic thin films.
Journal of Polymer Science Part B: Polymer Physics, 1998
We have used combinations of light, heat, and electrostatic fields to investigate the orientation of nonlinear azo-chromophores chemically incorporated into high glass transition temperature (T g) polyimides. A number of nonlinear optical polyimides have been synthesized in which the interaction between the nonlinear optical chromophore and the polymer main chain was systematically altered to determine to what extent this steric interaction influences the orientation of the nonlinear chromophore. Chromophores in polymers may be oriented by a number of methods: (a) polarized light at room temperature (i.e., photo-induced orientation or PIO), (b) polarized light and electric fields (i.e., photo-assisted poling or PAP) at temperatures ranging from room temperature to the polymer T g , and (c) electric fields at T g (thermal poling). While thermal poling and PIO are usually possible, PAP depends strongly on the molecular structure of the polymer. Previously we have shown that PIO can be accomplished at room temperature in a system where the nonlinear chromophore is embedded into the polyimide main chain via the donor substituent, and this orientation can only be thermally erased at temperatures approaching T g. In this article we show that, whereas photoisomerization can efficiently depole donor-embedded polyimides in a matter of few minutes at room temperature, PAP does not induce any polar order. This behavior is in marked contrast to a structurally related, side-chain, nonlinear polyimide, in which the azo chromophore is tethered via a flexible linkage to the polymer backbone. In this case some PAP occurs even at room temperature, while no PAP is observed for a donor-embedded system with a similar T g. We suggest that the orientation during PAP below T g in the side-chain polyimide is primarily due to the movement of the azo side chains, and there is a very little coupling of this motion to the main chain.