Molecular design, synthesis, and electro‐optic properties of novel Y‐type polyesters with high thermal stability of second harmonic generation

New Y-type polyester (3) containing nitrophenylazoresorcinoxy groups as NLO chromophores, which are components of the polymer backbone, was prepared and characterized. Polyester 3 is soluble in common organic solvents such as N,N-dimethylformamide and acetone. It shows a thermal stability up to 240 o C in thermogravimetric analysis with glass-transition temperature (T g ) obtained from differential scanning calorimetry near 116 o C. The second harmonic generation (SHG) coefficient (d 33 ) of poled polymer film at the 1064 nm fundamental wavelength is around 4.63 × 10 −9 esu. The dipole alignment exhibits a thermal stability even at 4 o C higher than T g , and there is no SHG decay below 120 o C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.

mentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

Synthesis and Properties of Novel Y-type Nonlinear Optical Polyester Containing Cyanovinylthiophene with Enhanced Thermal Stability of Second Harmonic Generation

Lee¹,

Kim

Jang³

et al. 2009

“…Side-chain NLO polymers have the advantages such as good solubility and homogeneity relative to the main-chain systems, but they often suffer from poor stability of dipole alignments at high temperatures. Recently we have prepared novel polyesters containing dioxynitrostilbene [20][21] or dioxybenzylidenemalononitrile 22 as NLO chromophores. The resulting polymers exhibit enhanced thermal stability of second harmonic generation (SHG), which stems from the stabilization of dipole alignment of the NLO chromophore.…”

Section: T T T (A)mentioning

confidence: 99%

Synthesis and Nonlinear Optical Properties of Novel Polyester with Enhanced Second Harmonic Generation Thermal Stability

Cho

Kim²,

Lee³

2010

Self Cite

Figure 1. Main-chain NLO polymers (a), side-chain NLO polymers (b), and T-type NLO polymers (c).Nonlinear optical (NLO) polymers received a great attention in recent years because of their potential applications in the field of electro-optic devices including ultrafast optical switches, high-speed optical modulators, and high-density optical data storage media.1-6 A potential NLO polymer has to be mechanically very strong and thermally stable with a high glass-transition temperature (Tg). In the developments of NLO polymers for electro-optic device applications, stabilization of electrically induced dipole alignment is one of important criteria; in this context, two approaches have been proposed to minimize the randomization of dipole alignment, namely the use cross-linking method 7-10 and the utilization of high T g polymers such as polyimides. [11][12][13][14][15][16] Various polyesters with NLO chromophores in the main chain 17 or in side chain [18][19] have been prepared and their properties studied. In general, main-chain NLO polymers have good thermal stability of dipole alignments, but they often do not dissolve in organic solvents, and their intractability make them unusable to fabricate stable films. Side-chain NLO polymers have the advantages such as good solubility and homogeneity relative to the main-chain systems, but they often suffer from poor stability of dipole alignments at high temperatures. Recently we have prepared novel polyesters containing dioxynitrostilbene 20-21 or dioxybenzylidenemalononitrile 22 as NLO chromophores. The resulting polymers exhibit enhanced thermal stability of second harmonic generation (SHG), which stems from the stabilization of dipole alignment of the NLO chromophore. In this work reported here, we prepared another novel polyester containing 2,5-dioxybenzylidenecyanoacetate groups as NLO chromophores. We selected the latter because they have a large dipole moment and are rather easy to synthesize. Furthermore, 2,5-dioxybenzylidenecyanoacetate group constitutes novel T-type NLO polyester (Fig. 1c), and this T-type NLO polyester has not yet been reported in the literature. Thus, we synthesized a new type of NLO polyester, in which the pendant NLO chromophores are components of the polymer backbone. This T-type NLO polymer is expected to have the advantages of both main-chain and side-chain NLO polymers namely stable dipole alignment and good solubility. After confirming the structure of the resulting polymer we investigated its properties such as solubility, Tg, thermal stability, second harmonic generation (SHG) activity and relaxation of dipole alignment. Results and DiscussionCompound 1 was prepared by the reaction of 2-chloroethyl vinyl ether with 2,5-dihydroxybenaldehyde. Compound 2 was prepared by the condensation reaction of compound 1 with methyl cyanoacetate. Compound 2 was hydrolyzed to yield acetaldehyde and diol 3. Monomer 3 was condensed with terephthaloyl chloride in a dry DMF solvent to yield polyester 4 containing the NLO chromophore 2,5-dioxybenzylid...

“…Side-chain NLO polymer systems have the advantages such as good solubility, homogeneity and high loading level of NLO chromophores relative to the main-chain systems, but they often suffer from poor stability of dipole alignments at high temperatures. Recently we have prepared novel polyesters containing dioxynitrostilbene [21][22] or dioxybenzylidenemalononitrile 23 as NLO chromophores. The resulting polymers exhibited enhanced thermal stability of second harmonic generation (SHG), which stemmed from the stabilization of dipole alignment of the NLO chromophore.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Novel Y-type Nonlinear Optical Polyester with Enhanced Thermal Stability of Second Harmonic Generation for Electro-Optic Applications

Cho¹,

Lee²,

Lee³

2010

Self Cite