Molecular Design, Synthesis and Properties of Novel Polyurethanes Containing Tetracyanocyclopropyl Groups as Piezoelectric Chromophores

Abstract

Summary: 1‐(2′,2′,3′,3′‐Tetracyanocyclopropyl)‐3,4‐di‐2′‐hydroxyethoxybenzene (4) was prepared by the reaction of bromomalononitrile with 3,4‐di‐(2′‐hydroxyethoxy)benzylidenemalononitrile (3). The dipole moment of diol 4, calculated by the ASED‐MO method, was 4.01 D. Diol 4 was condensed with 2,4‐toluenediisocyanate and 3,3′‐dimethoxy‐4,4′‐biphenylenediisocyanate to yield polyurethanes 5 and 6 containing tetracyanocyclopropane functionalities in the side‐group. The resulting polymers 5 and 6 were soluble in common organic solvents and the inherent viscosities were in the range of 0.25–0.30 dL · g−1. Solution‐cast films showed a thermal stability up to 280 °C with glass‐transition temperatures of 163–167 °C. The approximate lengths of aligned piezoelectric chromophores estimated from AFM images of poled polymer films were about 4 nm. Piezoelectric coefficients (d31) of the poled polymer films 5 and 6 were around 2.2–2.4 pC · N−1. These polymers showed good temporal and long‐term thermal stability due to the hydrogen bonding of the urethane linkage.

Synthesis of cross-linked polyurethane elastomers with the inclusion of polar-aromatic moieties (BA, PNBA and 3, 5-DNBA): Electrical and thermo-mechanical properties analysis

“…More recently, Petroff et al used the same strategy and created polar molecules doped polydimethylsiloxane (PDMS) foams and measured the electrical and mechanical properties and by tuning these properties they achieved a maximum d 33 piezo-coefficients about 153 pCN −1 [4]. Furthermore, many researchers showed that the inclusion of polar molecules in polyurethane can create either high piezoelectricity or NLO materials [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. We motivated by reviewing the previous works to do further experiments to observe the effect of polar moieties on other properties of polyurethane.…”

Molecular Orientation of Polyurethane Based Liquid Crystal Polymers by Corona Poling

“…In Figure 5(b), many parts have been protruded out from the surface after Corona poling, implying that urethane linkage of the cholesteric side chain has been interacted with the applied electrical voltage. Thus the polymer surface has been changed dramatically after poling, resulting in numerous hills and valleys in the surface structure, which were aligned to the poling direction (28,29). During poling mainly side chain alignment is possible as its length is very small compared to that of the main chain and is free for movement (30).…”

Synthesis and nonlinear optical properties of novel y‐type polyurethanes containing different concentrations of chromophore

“…6À8 One is to employ chemical crosslinking method [9][10][11][12][13] and the other is to utilize high glass transition temperature (T g ) polymers as matrix such as polyimides. Since polyurethane matrix with extensive hydrogen bonding between urethane linkages can form physical crosslinking system, [20][21][22][23][24] we choose this physical crosslinking system as polymer matrix to investigate the alignment stability of materials. For the chemical crosslinking method, the crosslinking temperature (T c ) has to be higher than T g to ensure an efficient poling of the chromophores before the crosslinking reaction starts.…”