Orientational decay in poled second-order nonlinear optical guest-host polymers: Temperature dependence and effects of poling geometry

Abstract

The orientational decay of chemically and thermally stable high-temperature chromophores doped into thin films made from polyimides and a variety of other polymeric hosts has been investigated. The chromophores are aligned using electric field poling and second-harmonic generation (SHG) is used to probe the decay of the electric field poling induced alignment. The decay rate of the SHG signal from films poled using both a corona discharge and side-by-side in-plane electrodes was measured. When electrodes are chosen so that the effects of charge injection are minimized, little difference has been observed between the orientational decays from films poled using the two methods for either an amorphous preimidized polyimide host or a highly anisotropic film poled during imidization. The films imidized during poling showed significant orientational stability at 250 °C for over 15 h after a fast initial partial decay. In addition, the decay of the SHG signal was measured as a function of temperature below the glass transition in a wide variety of different polymer host systems. The temperature dependence of the decay was found to be non-Arrhenius, but could be strongly correlated with the glass transition temperature of the guest-host system using an empirical relationship similar to the Williams–Landel–Ferry or Vogel–Tamann–Fulcher equation.

Synthesis and properties of a second-order nonlinear optical side-chain polyimide

“…However, detailed work on the poling procedure for the nonlinear characteristics of NLO side-chain polymers is limited. 19 Thus, we investigated the orientational process of the chromophore in the corona poling by measuring the SHG from the polymer. The SHG intensity was measured at the two conditions: (i) PI-1, poling during imidization; (ii) PI-2, poling after imidization.…”

Polymer Fibers as Carriers for Homogeneous Catalysts

“…Yet due to local molecular motions that are present even in the solid glassy stateor the partially crystalline state for that matter-the guest molecules are able to perform rotational and translational motions within the glassy matrix and solvents or functional molecules are able to perform diffusional motions in such solid matrices. [7,8] All of these arguments imply that polymers might be used as carriers in homogeneous catalysis allowing for the preparation of products that contain only a trace amount of catalyst or that are even completely free of contamination. The polymer carrier may provide further advantages due to specific dynamic environments affecting the reactions, such as chiral environments.…”

“…For example, it has been recognized for many decades that polymers are excellent choices as host matrices for guest-host systems designed for nonlinear optical applications, light-emitting diodes and information storage among other things. [5][6][7] Polymers frequently dissolve organic, metal organic, liquid crystalline low molar mass and oligomeric compounds up to high concentrations. This holds true not only for the molten but also for the solid glassy or partially crystalline state.…”

Generation of alkali-free and high-proton concentration layer in a soda lime glass using non-contact corona discharge

“…Corona discharge has been identified as a useful non-contact surface modification method for several materials. [15][16][17][18][19][20][21] The corona is a nondisruptive electrical discharge created by application of a high DC voltage between an anode and a cathode. For example, a material surface on the plate cathode electrode is charged with ions generated around the anode needle electrode, leading to the generation of a large electric field on the material surface.…”