Molecular Motion of Phosphazene-Bound Nonlinear Optical Chromophores

Abstract

The behavior of nonlinear optical (NLO) groups linked to a polyphosphazene chain was studied by solid-state NMR spectroscopy. A series of poly(organophosphazenes) was prepared with the general structure [NP(RN(CH3)C6H4NO2)x{O(CH2CH2O)2CH3}2-x]n, where x < 0.5 and the spacer group R ) O(CH2)2, O(CH2)6, or OCH2(2-pyrrolidino), in addition to the stilbene-containing polyphosphazene [NP{O(CH2)2N(CH3)C6H4CHdCHC6H4NO2}0.4{O(CH2CH2O)2CH3}1.6]n. Structural characterization for the above polymers was achieved by 31 P NMR spectroscopy, differential scanning calorimetry, and elemental microanalysis. (Methoxyethoxy)ethoxy (MEE) cosubstituent poly(organophosphazenes) bearing O(CH2)2N(CH3)C6H4NO2 and O(CH2)6N(CH3)C6H4NO2 side groups were selected for study by roomtemperature and variable-temperature solid-state 31 P and 13 C NMR spectroscopy. The variabletemperature solid-state 13 C NMR spectra indicated that the use of a longer spacer group between the polymer backbone and the aromatic portion of the NLO side group lowers the temperature at which chromophore motion is quenched. This implied that the use of such structures may accelerate the randomization of NLO side group orientation at ambient temperatures following poling. This behavior was mirrored in the solid-state variable-temperature 31 P NMR spectra, which suggested that side chain and polymer backbone motion may be coupled.

Synthesis and nonlinear optical properties of polyphosphazenes with binaphtholyl and indole side groups

“…Most polyphosphazenes have very high molecular weight, and they are usually amorphous, soluble, and easily prepared 1–4. Because of these advantages, they were considered as an excellent candidate for electrooptical (EO) applications 5–7. In 1991, a second‐order nonlinear optical (NLO) chromophore, dispersed red‐1 (DR‐1), was first linked to the phosphorus–nitrogen backbone by Allcock et al5 to synthesize new NLO polymeric materials; the resultant polyphosphazenes showed good properties such as stability and processibilty and demonstrated that polyphosphazenes might be promising polymeric materials for the NLO applications, except that T g was only 58°C.…”

Preparation and properties of three novel poly(phosphazene‐aryl amide)s containing cyclotriphosphazene structures

“…Among this family of compounds, the hexachlorocyclotriphosphazenes (HCCP) N 3 P 3 Cl 6 received maximum attention. In the recent 10 years, research about the functionality of polyphosphazene is very active which includes flame retardant, special rubber, high temperature resistant material, liquid crystal, photoelectricity materials, etc 11–15. However, to date, very few literature references of poly(cyclotriphosphazene‐aryl amide)s were provided.…”

Second-order nonlinear optical properties of polyphosphazenes containing multi-dipolar and imidazolebased chromophores

“…They present a number of useful features for practical devices, such as the excellent flexibility of the backbone, high thermal and oxidative stability, optical transparency from 220 nm to the near-IR region, and controlled covalent incorporation of chromophores can be easily accomplished over a broad concentration range. Recently, some new synthetic routes [20][21][22][23][24][25][26] have been developed for the preparation of polyphosphazenes with large molecular hyperpolarizabilities and high glass-transition temperatures.…”