| Second-order nonlinear optical (NLO) polymeric materials have attracted considerable attention due to their potential applications in broad bandwidth telecommunication, information processing, and radar systems. Electro-optic (EO) polymeric materials, which possess large and rapid NLO responses, low dielectric constant, high laser damage thresholds, low cost, superior chemical flexibility and ease of processing, have been predicted to be the NLO polymers closest to commercialization. Before their commercialization, it is a challenge to synthesize EO polymers with large NLO effects, high thermal stability of the dipole moment after poling and low optical loss to fit the requirements of EO apparatus. During the past two decades, EO polymers based on high performance polymers with high glass transition temperatures (Tg's) have been one of the most active research fields due to their high thermal stability of the dipole moment after poling and long lifetime that are the two key problems in their applications. In this thesis, five kinds of novel EO polymers are designed and synthesized towards these two key problems. In consideration of the importance of high Tg polymers in the design and synthesis of EO polymers, two novel high performance polymers are prepared for the purpose of potential application in the synthesis of EO polymers. The main contents and discoveries are described as the following:Recent progress of EO polymeric materials is reviewed in Chapter 1. The emphasis is located on the design and synthesis of seven kinds of EO polymers including guest-host polymers, side-chain polymers, main-chain polymers, cross-linking polymers, dendrimers, dendronized polymers, organic-inorganic hybrid polymers and supramolecular self-assembly polmers. Then the future directions of the EO polymers are discussed. The strategies and main contents of this thesis have also been outlined.Poly(arylene ether sulfone)s represent a kind of high performance polymers with excellent thermal properties and good processibility. However, there are still few reports investigating their NLO properties. In Chapter 2, a convenient and efficient postfunctionalization strategy to develop poly(arylene ether sulfone)-based side-chain EO polymers has been explored. Six end-on attached and one side-on attached EO polymers containing NLO chromophores in the side chains are prepared by esteriflcation reactions of poly(arylene ether sulfone)s in the presence of 1, 3-dicyclohexylcarbodiimide (DCC) and 4-(N, N-dimethylamino)pyridine (DMAP) at room temperature. The molar densities of the NLO chromophores of the resulting polymers are estimated to be above 50 % and all the polymers are readily soluble in common organic solvents. The Tg's of all of the polymers are above 160 癈, and the polymers are thermally stable up to 200 ℃ in both air and argon. The NLO coefficients (d33) of the poled polymer films are determined to be in the range of 4.8-84.7 pm/V by in-situ second harmonic generation (SHG) measurement, and the nonresonant NLO coefficient (d33(oo)) values of the polymers are estimated to be in the range of 4.8-10.6 pm/V by using the approximation two-level model. The thermal stability of the NLO activities of the polymers induced by poling was measured by the depoling experiments, which indicate that the decay temperatures of the SHG signals of five polymers are in the range of 105-160℃, and their half decay temperatures are in the range of 135-175癈. The orientation behaviors of theIVpoled films of the polymers are studied by UV-Vis spectroscopy, and their order parameters (0) are calculated to be in the range of 0.11-0.19 abse on the results of the UV-Vis spectra of the films. The side-on poly(arylene ether sulfone) EO polymer exhibits the highest decay temperature (160), half decay temperature (175癈) and order parameter (0.19), which indicates that this EO polymer is easily poled and possesses good thermal stability of the dipole moment after poling. Due to the mild synthetic conditions, many other environment-sensitive high NLO chro...
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