Modified Polyimide Side-Chain Polymers for Electrooptics

Abstract

New modified polyimide polymers with pendent side group nonlinear optical (NLO) azo chromophores and moderate to high glass transition temperatures (140 °C < Te < 190 °C) have been prepared. Corona poled films of these polymers possess large nonlinear optical susceptibilities of d3J = 23 pm/V and electrooptic (EO) coefficients of ri3 -6.5 pm/V at a wavelength of X = 1.3 gm. The structural properties (glass transition, molecular weight, chromophore density) and optical properties (refractive index, optical nonlinearity) of these polyimides can easily be varied to fulfill the requirements of potential electrooptic devices. Due to the relatively high glass transition temperatures of these polymers, long-term stability of the optical nonlinearity of typically one to hundreds of years at operating temperatures of 80-100 °C is predicted from accelerated time-temperature measurements. Using a development of a phenomenological theory of the glass transition, a normalized relaxation law is proposed with (Tg -T)/T as the relevant scaling parameter.

Second-order non-linear optical polymers

“…Besides polyimides, polymaleimides and copolymers are another class of polymers with high glass transition temperatures. Prêtre et al 108) synthesized chromophore functionalized maleimide (90%) copolymers with styrene with different spacer lengths of the attached NLO azo chromophore (dialkylaminonitroazobenzene). T g 's up to 172 8C were obtained and a d 31 of 23 pm/V and r 13 of 6.5 pm/V (measured at 1 300 nm).…”

Synthesis and characterization of polymaleimides containing 4-cyanobiphenyl-based side groups for nonlinear optical applications

“…It should be noted that the viscosimetric studies provide only an order of magnitude of M n owing to the approximation made in relation (2), namely that polymaleimide and substituted polymaleimides of equal number-average degree of polymerization, DP n , exhibit identical intrinsic viscosity in DMF. 39 This can be seen by comparison of the results for PM 8 The infrared spectra of polymers PM n show almost complete removal of monomer as indicated by the disappearance of the cis ͘CAC͗ band at ca. 692 cm…”

“…7 The relaxation processes in these copolymers have been investigated. 5,8,9 An alternating copolymer of maleimide and styrene with an azo chromophore attached to the maleimide unit through a spacer of only two methylenic units was predicted to have a relaxation time of about 3 years at an operating temperature of 100°C. 8 Lengthening the spacer from two to three methylenic units, to improve the poling efficiency by decoupling the chromophores from the main chain, was found to decrease T g from 170 to 140°C and to drastically effect the temporal stability of the induced polar order.…”

Nonlinear optical properties of push–pull polyenes for electro-optics

“…Because of the high chromophore loading (56 wt %), this side-chain polymer exhibits high NLO effects. 14,20,21 For the polymers the EO response at frequency is given by 7,20 r 33 ϭ 2Nf ␤͑Ϫ; , , 0͒…”