Internal electric field and second harmonic generation in the blends of vinylidene fluoride-trifluoroethylene copolymer and poly(methyl methacrylate) with a pendant nonlinear optical dye

Abstract

This paper presents the internal electric field created by the preferentially oriented /3-crystallite dipoles in the blends of 75 mol % vinylidene fluoride-25 mol % trifluoroethylene copolymer (P(VDF-TrFE)) and poly(methyl methacrylate) (PMMA) and the second harmonic generation (SHG) from the oriented /3-crystallite dipoles and that from the nonlinear optical (NLO) dyes noncentrosymmetrically aligned by the internal electric field. We have also prepared the copolymer of methyl methacrylate (MMA) with a vinyl monomer having a NLO pendant amino-nitro-azobenzene (P(MMA-co-MMA-DRl)) as a SHG active polymer. The blends of both P(VDF-TrFE)/PMMA and P(VDF-TrFE)/P(MMA-co-MMA-DRl) with lowDRl content (experimentally up to 4 mol %) show optical clarity that is desirable for SHG materials. Internal electric fields (Ei) of 1.7-3.2 MV/cm, which is significantly larger than the applied field of 0.8 MV/cm, were measured at the P(VDF-TrFE) content above 70 mol %. SHG coefficient <¿33 values are 3.3 X *9,2.3 x 10~9, and 0.9 X10-9 esu for P(VDF-TrFE), (90/10) P(VDF-TrFE)/PMMA, and (90/10) P(VDF-TrFE)/P(MMA-co-MMA-DR1), respectively. Temperature profiles of E¡ for the blends are shared by those of pyroelectricity and those of ¿33. Their activities are not significantly depressed at the glass transition temperature T, but are drastically lost at the temperature around the Curie transition temperature, which is higher than Tg. We will discuss the nature of the thermal stability of the internal electric field, pyroelectricity, and SHG activity, relating to the order-disorder transition of /3-crystallite dipoles at the Curie transition temperature.

Precise study of nonlinear optical coefficients and hyperpolarizabilities in cold-drawn and poled ferroelectric Nylon 11 films

“…SHG of ferroelectric copolymer of vinylidene fluoride and trifluoroethylene ͓P͑VDF-TrFE͔͒ was also studied [5][6][7] and the proportionality between the d 33 value and P r was reported. 6 Furthermore, second-order optical nonlinearity was measured for the blend of P͑VDF-TrFE͒ with poly͑methyl methacrylate͒ ͑PMMA͒ ͓P͑VDF-TrFE͒/PMMA blends͔ 8 and nonlinear optical ͑NLO͒ dye dispersed PVDF/PMMA blends. 9 The second-order optical nonlinearity in drawn and poled Nylon 11, which shows clear ferroelectric polarization reversal, 10,11 has been investigated by Tsutsumi et al 12 In a previous study, 12 the large internal electric field created by the aligned crystallite dipoles and second-order optical nonlinearity has been investigated for cold-drawn and poled Nylon 11 films.…”

The synthesis of aminoazobenzenes and the effect of intermolecular hydrogen bonding on their photoisomerization

“…A slight broadening of this band was also observed. The broadening and redshift of the absorption band can be assigned to the development of a local internal electric field caused by parallel dipole alignment [20,21]. The absorption maxima of II aec in PMMA film only shifted about 4.0e6.8 nm comparing to those in solution, which were smaller than those for I aec .…”

Novel Nonlinear Optical Polymers

“…The SH signal averaged on a Stanford Research Systems (SRS) model SR-250 gated integrator and boxcar averager module was transferred to a microcomputer through a SRS model SR-245 computer interface module. The details of the experimental procedures were previously described (13,14).…”