Synthesis and characterization of aromatic cyclolinear phosphazene polyetherketones containing bis‐Spiro‐substituted cyclotriphosphazene unit

A novel monomer, 2,2‐bis‐(4′‐fluorobenzoylphenoxy)‐4,4,6,6‐bis[spiro‐(2′,2″‐dioxy‐1′, 1′‐biphenylyl)] cyclotriphosphazene, was synthesized and polymerized with 4,4′‐difluorobenzophenone as a comonomer and 4,4′‐isopropylidenediphenol or 4,4′‐(hexafluoroisopropylidene) diphenol in N,N‐dimethylacetamide at 162 °C for 4 h to give two series of aromatic cyclolinear phosphazene polyetherketones containing bis‐spiro‐substituted cyclotriphosphazene groups. The structure of the monomer was confirmed by ¹H, ¹³C, and ³¹P NMR. The effect of the incorporation of the bis‐spiro‐substituted cyclotriphosphazene group on the thermal properties of these polymers was investigated by DSC and thermogravimetric analysis. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2993–2997, 2001     

Molecular design,synthesis, and nonlinear optical properties of novel T‐type polyimides with exceptionally high thermal stability of the second harmonic generation

2,5‐Bis‐(3,4‐dicarboxyphenylcarboxyethoxy)‐4′‐nitrostilbene dianhydride was prepared and reacted with 1,4‐phenylenediamine, 4,4′‐oxydianiline, 4,4′‐diaminobenzanilide, and 4,4′‐(hexafluoroisopropylidene)dianiline to yield unprecedented novel T‐type polyimides ( 4 – 7 ) containing 2,5‐dioxynitrostilbenyl groups as nonlinear optical chromophores, which constituted parts of the polymer backbones. 4 – 7 were soluble in polar solvents such as acetone and N,N‐dimethylformamide. They showed thermal stability up to 300 °C in thermogravimetric analysis thermograms; the glass‐transition temperatures obtained from differential scanning calorimetry thermograms were around 153 °C. The second harmonic generation (SHG) coefficients (d₃₃) of poled polymer films at the 1064‐cm^?1 fundamental wavelength were around 4.35 × 10^?9 esu. The dipole alignment exhibited exceptionally high thermal stability even at 45 °C higher than the glass‐transition temperature, and there was no SHG decay below 200 °C because of the partial main‐chain character of the polymer structure, which was acceptable for nonlinear optical device applications. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3189–3199, 2004     

Synthesis of poly(arylene ether ketone)s bearing skeletal crown ether units for cation exchange membranes

Poly(arylene ether ketone)s (PAEKs) are the most commonly known high‐performance materials used for ion exchange and fuel cell membranes. Described here is the design of novel sulfonated PAEKs (SPAEKs) and nonsulfonated PAEKs containing crown ether units in the main chain, which can be used in sensing applications and ion‐selective membranes. To this end, 4,4′(5′)‐di(hydroxybenzo)‐18‐crown‐6 was synthesized and used as monomer in a step growth polymerization to form crown ether‐containing PAEKs and SPAEKs. The successful synthesis of PAEKs containing 18‐crown‐6 and sulfonate groups was confirmed by gel permeation chromatography, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. Membranes are fabricated from the sulfonated polymers. Potassium ion transport properties of the SPAEK and crown ether‐containing SPAEK membranes are assessed by diffusion dialysis. Potassium ion diffusion in the crown ether‐containing SPAEK membranes is almost four times lower than K⁺ diffusion in the native polymer membranes, without crown ether. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2786–2793     

Transparent and soluble polyimide films containing 4,4′‐isopropylidenedicyclohexanol (Cis‐HBPA) units: Preparation,characterization, thermal,mechanical, and dielectric properties

To develop colorless and soluble polyimide films, cis‐hydrogenated bisphenol A (cis‐HBPA) was successfully separated from HBPA isomers, and two novel monomers containing cis‐HBPA unit, 4,4 ′ ‐(4,4 ′ ‐isopropenylbicyclohexyloxy) diphthalic anhydride (HBPADA) and 4,4 ′ ‐(4,4 ′ ‐isopropenylbicyclohexyloxy) dianiline (f) were designed and synthesized. PI–(1 – 5) were achieved from HBPADA and five kinds of aromatic diamines and PI – 6 from HBPADA and semiaromatic diamine f via a two‐step thermal imidization. All the polyimides could afford flexible, tough, and transparent films with transparency as high as 86% at 450 nm. Surprisingly, the polyimides containing cis‐HBPA unit exhibited excellent solubility not only in polar solvents such as N, N‐dimethylacetamide, but also in low boiling solvents such as chloroform and dichloromethane. Additionally, analogues aromatic PI – 7 derived from 4,4 ′ ‐(hexafluoroisopropylidene)‐diphthalic anhydride (6FDA) and 2,2‐bis(4‐aminophenyl)hexafluoropropane (e) was obtained for comparison with PI–(1 – 6) on aspects of thermal, mechanical, soluble, optical, electrical, and morphological properties. The structure‐property relationships of PI–(1 – 7) were investigated in detail. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2115–2128     

Characterization of two‐ and three‐photon absorption of polyfluorene derivatives

Fluorene‐based polymer derivatives are promising materials for organic electronic devices because of their photoluminescence and electroluminescence, good film‐forming ability, and favorable chemical and thermal properties. Although optical properties of polyfluorene have already been reported, most of the studies focused on the linear optical properties, whereas nonlinear optical characteristics have only recently received more detailed attention. Here, we report on two polyfluorene derivatives, poly(9,9′‐n‐dihexyl‐2,7‐fluorenediyl) (LaPPS 10) and poly(9,9′‐n‐dihexyl‐2,7‐fluorene‐diyl‐vinylene) (LaPPS 38), which present intense nonlinear absorption and fluorescence. Two‐photon absorption cross‐section properties of both polymers were characterized in the spectral range from 500 nm up to 900 nm, reaching peak values around 2000 Göppert Mayer units. Optical limiting behavior and two‐photon‐induced fluorescence of both polymers have also been investigated. Furthermore, the first molecular hyperpolarizability of the polymers was also studied using hyper‐Rayleigh scattering. In addition, the three‐photon absorption (3PA) spectra of both materials were also investigated, and 3PA cross‐section values in the order of 1 × 10^?78 cm⁶ s² photon^?2 were observed. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 747–754     

Synthesis and properties of novel Y‐type nonlinear optical polyimides with high thermal stability of second harmonic generation

2,4‐Bis‐(3,4‐dicarboxyphenylcarboxyethoxy)‐1‐(2,2‐dicyanovinyl)benzene dianhydride (4) was prepared and reacted with 4,4′‐oxydianiline, 4,4′‐diaminobenzanilide and 4,4′‐(hexafluoroisopropylidene)dianiline to yield novel Y‐type polyimides 5‐7 containing 2,4‐dioxybenzylidenemalononitrile groups as nonlinear optical (NLO) chromophores, which constitute parts of the polymer backbone. The resulting polyimides 5‐7 are soluble in polar solvents such as dimethylsulfoxide and N,N‐dimethylformamide. Polymers 5‐7 showed a thermal stability up to 330 °C in thermogravimetric analysis thermograms with T_g values obtained from differential scanning calorimetry thermograms in the range 179–194 °C. The second harmonic generation (SHG) coefficients (d₃₃) of poled polymer films at the 1064 nm fundamental wavelength were around 5.56 × 10^?9 esu. The dipole alignment exhibited exceptionally high thermal stability even at 20 °C higher than the glass‐transition temperature there was no SHG decay below 215 °C because of the partial main‐chain character of polymer structure, which is acceptable for NLO device applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3078–3087, 2008     

Synthesis of highly refractive and transparent polyimides derived from 4,4′‐thiobis[2″,6″‐dimethyl‐4″‐(p‐phenylenesulfanyl)aniline]

New sulfur‐containing aromatic diamines with methyl groups at the ortho position of amino groups have been developed to prepare highly refractive and transparent aromatic polyimides (PIs) in the visible region. All aromatic PIs derived from 4,4′‐thiobis[2″‐methyl‐4″‐(p‐phenylenesulfanyl)aniline ( 2 ), 4,4′‐thiobis[2,″6″‐dimethyl‐4″‐(p‐phenylenesulfanyl)aniline ( 5 ), and aromatic dianhydride, 4,4′‐[p‐thiobis(phenylenesulfanyl)]diphthalic anhydride ( 6 ) were prepared via a two‐step polycondensation. All PIs showed good thermal properties, such as 10% weight loss temperature in the range of 497–500 °C and glass transition temperatures above 196 °C. In addition, the PIs showed good optical properties, such as optical transparency above 75% at 450 nm with a 10‐μm film thickness, high refractive indices ranging from 1.7135 to 1.7301, and small in‐plane/out‐of‐plane birefringences between 0.0066 and 0.0076. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 656–662, 2010     

Synthesis and characterization of high refractive index polyimides derived from 2,5‐Bis(4‐Aminophenylenesulfanyl)‐3,4‐Ethylenedithiothiophene and aromatic dianhydrides

The authors describe the synthesis and characterization of the polyimide (PI) series containing a 2,5‐bis(4‐aminophenylenesulfanyl)‐3,4‐ethylenedithiothiophene (APSEDTT) moiety in their main chain. The APSEDTT monomer with high sulfur content was prepared and polymerized with several aromatic dianhydrides such as 4,4′‐[p‐thio bis(phenylenesulfanyl)]diphthalic anhydride (3SDEA), 4,4′‐biphthalic anhydride (BPDA), and 4,4′‐oxydiphthalic anhydride (ODPA) by the traditional two‐step polycondensation procedure. All PIs exhibited high transparency, higher than 75% at 550 nm for a thickness of about 20 μm and good thermal properties such as thermal decomposition temperatures (T_10%) in the range of 409–521 °C. In addition, the PIs have extraordinarily excellent optical properties in refractive index and birefringence as originally designed. In particular, the PI derived from APSEDTT and 3SDEA showed a high refractive index (1.7586), and a low birefringence (0.0087) because of their very high sulfur content (27.7%). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 944–950     

Synthesis and properties of thermosetting polymers from a phosphorous‐containing fatty acid derivative

A new phosphorous‐containing fatty acid diepoxide was obtained from 10‐undecenoyl chloride and 10‐(2′,5′‐dihydroxyphenyl)‐9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide and crosslinked with 4,4′‐diaminodiphenylmethane and bis(m‐aminophenyl)methylphosphine oxide. The properties of the thermosetting materials were evaluated by differential scanning calorimetry, dynamic mechanical thermal analysis, thermogravimetric analysis, and limiting oxygen index (LOI). Thermal and thermooxidative degradation was studied by gas chromatography/mass spectrometry, FTIR, ³¹P magic angle spinning NMR spectroscopy, and scanning electron microscopy. LOI values indicate good flame‐retardant properties that are related to the formation of a protective phosphorous‐rich layer that slowed down the degradation and prevented it from being total. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5630–5644, 2006     

Study on side‐chain second‐order nonlinear optical polyimides based on novel chromophore‐containing diamines. II. Copolyimides possessing direct photolithographic features

Second‐order nonlinear optical copolyimides were prepared from a novel chromophore‐containing diamine, 4‐nitro‐4′‐[N‐(4,6‐di‐4‐aminophenylamino)‐1,3,5‐triazin‐2‐yl]aminoazobenzene, a codiamine, 4,4′‐diamino‐3,3′‐dimethyldiphenylmethane, and benzophenone‐3,3′,4,4′‐tetracarboxylic dianhydride by a traditional two‐step process, which includes a solution polycondensation followed by a chemical imidization. Some of the polyimides (PIs) obtained possessed direct photolithographic features, and good photolithographic patterns were easily obtained. All PIs exhibited high‐glass transition temperatures (235–246 °C) and high thermal‐decomposition temperatures. They were also soluble in strong polar aprotic solvents such as N‐methyl‐2‐pyrrolidone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, and γ‐butyrolactone. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1419–1425, 2001     

Synthesis and characterization of novel fully aliphatic polyimidosiloxanes based on alicyclic or adamantyl diamines

A series of fully aliphatic polyimidosiloxanes (APISiO) were prepared by poly(addition/condensation) reaction of bicyclo [2,2,2] oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride or cyclobutane‐1,2,3,4‐tetracarboxylic dianhydride and varying compositions of 1,3‐bis (3‐amino propyl)‐tetra methyl disiloxane and rigid adamantyl diamines (1,3‐diaminoadamantane or 3,3′‐diamino‐1,1′‐diadamantane) or flexible alicyclic diamines (4,4′‐methylene bis(cyclohexylamine) or 4,4′‐methylene bis(2‐methylcyclohexylamine)). High temperature one‐step synthesis in m‐cresol was employed to obtain APISiOs with intrinsic viscosity in the range of 0.28–0.59 dL/g. The final materials were characterized by ¹H and ¹³C NMR, ²⁹Si‐MAS‐NMR and IR spectroscopic analysis, thermogravimetric and differential scanning calorimetric analysis, and wide angle X‐ray diffractometry. UV–visible spectra revealed the optical behavior of the polyimides. It was found that the APISiOs containing appropriate ratio of adamantyl moieties together with flexible aliphatic siloxane groups exhibit good thermal and mechanical stabilities, solubility, fair transparency, and low dielectric constant (2.4–2.7). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5254–5270, 2006     

Poly‐Schiff bases. V. Synthesis and characterization of novel soluble fluorine‐containing polyether azomethines

A new dialdehyde monomer, 4,4′‐(hexafluoroisopropylidine) bis(p‐phenoxy) benzaldehyde, was prepared; it led to a number of novel poly‐Schiff bases in reactions with different diamines, such as 4,4′‐diaminidiphenyl ether, 4,4′‐(isopropylidine) bis(p‐phenoxy) dianiline, 4,4′‐(hexafluoroisopropylidine) bis(p‐phenoxy) dianiline, and benzidine. The polymers were characterized with viscosity measurements, nitrogen analyses, and IR and ¹H NMR spectroscopy. These poly‐Schiff bases showed good thermal stability up to 491 °C for 10% weight loss in thermogravimetric analysis under air and high glass‐transition temperatures up to 215 °C in differential scanning calorimetry. These polymers were soluble in a wide range of organic solvents, such as CHCl₃, dimethylformamide (DMF), dimethyl sulfoxide, and 1‐methyl‐2‐pyrrolidon (NMP), and were insoluble in toluene and acetone. Thin films of these polymers cast from DMF exhibited tensile strengths up to 38 MPa. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 383–388, 2001     

Substituent effects on electrochemical and electrochromic properties of aromatic polyimides with 4‐(carbazol‐9‐yl)triphenylamine moieties

Three series of aromatic polyimides with 4‐(carbazol‐9‐yl)triphenylamine moieties were prepared from the polycondensation reactions of 4,4′‐diamino‐4″‐(carbazol‐9‐yl) triphenylamine (1), 4,4′‐diamino‐4″‐(3,6‐di‐tert‐butylcarbazol‐9‐yl)triphenylamine (t‐Bu‐1), and 4,4′‐diamino‐4″‐(3,6‐dimethoxycarbazol‐9‐yl)triphenylamine (MeO‐1), respectively, with various commercially available tetracarboxylic dianhydrides. In addition to high thermal stability and good film‐forming ability, the resulting polyimides exhibited an ambipolar electrochromic behavior. The polyimides based on t‐Bu‐1 and MeO‐1 revealed higher redox‐stability and enhanced electrochromic performance than the corresponding ones based on 1 because the active sites of their carbazole units are blocked with bulky t‐butyl or electron‐donating methoxy groups. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1172–1184     

Synthesis and properties of novel polyurethanes containing 3,4‐dioxybenzylidenecyanoacetate group as a nonlinear optical chromophore

Methyl 3,4‐di‐(2′‐hydroxyethoxy)benzylidenecyanoacetate ( 3 ) was prepared by hydrolysis of methyl 3,4‐di‐(2′‐vinyloxyethoxy)benzylidenecyanoacetate ( 2 ). Diol 3 was condensed with 2,4‐toluenediisocyanate, 3,3′‐dimethoxy‐4,4′‐biphenylenediisocyanate, and 1,6‐hexamethylenediisocyanate to yield polyurethanes 4 – 6 containing the nonlinear optical chromophore 3,4‐dioxybenzylidenecyanoacetate. The resulting polyurethanes 4 – 6 were soluble in common organic solvents such as acetone and dimethylformamide. Polymers 4 – 6 indicated thermal stability up to 300 °C in thermogravimetric thermograms with glass‐transition temperature values obtained from differential scanning calorimetric thermograms in the range of 78–102 °C. The second‐harmonic generation coefficients (d₃₃) of the poled polymer films were around 6.9 × 10^?9 esu. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1742–1748, 2002     

Synthesis and characterization of novel fluorinated aromatic polyimides derived from 1,1‐bis(4‐amino‐3,5‐dimethylphenyl)‐1‐(3,5‐ditrifluoromethylphenyl)‐2,2,2‐trifluoroethane and various aromatic dianhydrides

A novel fluorinated aromatic diamine, 1,1‐bis(4‐amino‐3,5‐dimethylphenyl)‐1‐(3,5‐ditrifluoromethylphenyl)‐2,2,2‐trifluoroethane (9FMA), was synthesized by the coupling reaction of 3′,5′‐ditrifluoromethyl‐2,2,2‐trifluoroacetophenone with 2,6‐dimethylaniline under the catalysis of 2,6‐dimethylaniline hydrochloride. A series of fluorinated aromatic polyimides were synthesized from 9FMA and various aromatic dianhydrides, including pyromellitic dianhydride, 3,3′4,4′‐biphenyl tetracarboxylic dianhydride, 4,4′‐oxydiphthalic anhydride, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA), and 4,4′‐hexafluoroisopropylidene diphthalic anhydride, via a high‐temperature, one‐stage imidization process. The inherent viscosities of the polyimides ranged from 0.37 to 0.74 dL/g. All the polyimides were quickly soluble in many low‐boiling‐point organic solvents such as tetrahydrofuran, chloroform, and acetone as well as some polar organic solvents such as N‐methyl‐2‐pyrrolidinone, N,N′‐dimethylacetamide, and N,N′‐dimethylformamide. Freestanding fluorinated polyimide films could be prepared and exhibited good thermal stability with glass‐transition temperatures of 298–334 °C and outstanding mechanical properties with tensile strengths of 69–102 MPa and elongations at break of 3.3–9.9%. Moreover, the polyimide films possessed low dielectric constants of 2.70–3.09 and low moisture absorption (<0.58%). The films also exhibited good optical transparency with a cutoff wavelength of 303–351 nm. One polyimide (9FMA/BTDA) also exhibited an intrinsic negative photosensitivity, and a fine pattern could be obtained with a resolution of 5 μm after exposure at the i‐line (365‐nm) wavelength. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2665–2674, 2006     

Synthesis and optical and electrochemical properties of thermotropic,liquid‐crystalline,semirigid copolyesters based on 2,5‐diphenyl‐1,3,4‐thiadiazole units

Novel thermotropic liquid‐crystalline (LC) copolyesters were prepared with three disubstituted (4,4′‐, 3,4′‐, and 3,3′‐) dioxydiundecanol derivatives of terphenyl analogues of 1,3,4‐thiadiazole [2,5‐diphenyl‐1,3,4‐thiadiazole (DPTD)], and their optical and electrochemical properties were examined. Their structures were characterized with Fourier transform infrared, ¹H NMR spectroscopy, and elemental analyses. The thermal and mesomorphic properties of the copolyesters were investigated with differential scanning calorimetry measurements, polarized microscopy observations, and X‐ray analyses; the data suggested that these copolymers formed LC smectic or nematic phases. The mesomorphic tendency decreased in the following order: 4,4′‐DPTD and 3,4′‐DPTD copolyesters > 4,4′‐DPTD and 3,3′‐DPTD copolyesters > 3,4′‐DPTD and 3,3′‐DPTD copolyesters. Solution and solid‐state ultraviolet–visible (UV–vis) and photoluminescence spectra indicated that the copolyesters displayed maximum absorbances and blue emissions according to the DPTD unit; the peak maxima of absorption and emission spectra of the copolyesters shifted to lower wavelengths in the aforementioned order for the LC properties. Cyclic voltammetry measurements indicated that the electrochemical band gaps of the polyesters estimated from the onset of reduction and oxidation processes were almost the same as the optical band gaps determined from the solid‐state UV–vis spectral data. The DPTD unit enhanced the hole‐injection barrier and improved the charge‐injection balance in these polyesters. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1511–1525, 2005     

Synthesis and properties of novel soluble poly(amide‐imide)s with different pendant substituents

Two types of novel fluorinated diimide‐diacid monomers—[2,2′‐(4,4′‐(3′‐methylbiphenyl‐2,5‐diyl)bis(oxy)bis(3‐(trifluoromethyl)‐4,1‐phenylene))bis(1,3‐dioxoisoindoline‐5‐carboxylic acid)] (III) and [2,2′‐(4,4′‐(3′‐(trifluoromethyl)biphenyl‐2,5‐diyl)bis(oxy)bis(3‐(trifluoromethyl)‐4,1‐phenylene))bis(1,3‐dioxoisoindoline‐5‐carboxylic acid)] (IV)—were respectively designed and prepared by the condensation of diamines I and II with two molar equivalents of trimellitic anhydride. From both diimide‐diacids, two series of novel poly(amide‐imide)s (PAIs) (IIIa–IIIe and IVa–IVe) bearing different pendant groups were prepared by direct polymerization with various aromatic diamines (a–e). All the PAIs had a high glass transition temperatures (T_gs, 232–265 °C), excellent thermal stability (exhibiting only 5% weight loss at 493–542 °C under nitrogen) and good solubility in various organic solvents due to the introduction of the bulky pendant groups. The cast films of these PAIs (80–90 μm) had good optical transparency (73–81% at 450 nm, 85–88% at 550 nm and 87–89% at 800 nm) and low dielectric constants (2.65–2.98 at 1 MHz). The spin‐coated films of these PAIs presented a minimum birefringence value as low as 0.0077–0.0143 at 650 nm and low optical absorption at the near‐infrared optical communication wavelengths of 1310 and 1550 nm. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3243–3252     

Preparation and property of two soluble oxadiazole‐containing functional polyacetylenes

Two novel high‐molecular weight functional polyacetylenes (PA) bearing oxadiazole group as a pendant, poly(2‐(4‐octoxyphenyl)‐5‐(4‐ethynylphenyl)‐1,3,4‐oxadiazole) ( P1 ) and poly(2‐(4′‐octoxyphenyl)‐5‐(4′‐propynyloxyphenyl)‐1,3,4‐oxadiazole) ( P2 ) were synthesized by [Rh(nbd)Cl]₂‐Et₃N catalysts. Both polymers were soluble in common organic solvents such as CHCl₃ and tetrahydrofuran. Their structures and properties were characterized and evaluated with FTIR, NMR, UV, thermogravimetric analysis, GPC, optical‐limiting and nonlinear optical analyses, respectively. The results show that linkage of oxadiazole chromophore to PA main chain has improved the nonlinear optical (NLO) property of PA, and endowed PA with novel optical limiting properties and enhanced thermal stability. Simultaneously, the optical‐limiting and NLO properties of the polymers were sensitive to their molecular structures. P1 with oxadiazole directly incorporated into PA main chain as a pendant showed better performances and larger third‐order nonlinear optical susceptibility than P2 with oxadiazole incorporated into PA main chain via a spacer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2072–2083, 2008     

Preparation and phase behavior of side‐chain cholesteric liquid‐crystalline elastomers

A series of new side‐chain cholesteric elastomers derived from cholesteryl 4‐(10‐undecylen‐1‐yloxy)‐4′‐ethoxybenzoate and phenyl 4,4′‐bis(10‐undecylen‐1‐yloxybenzoyloxy‐p‐ethoxybenzoate) was synthesized. The chemical structures of the monomers were confirmed by elemental analyses, Fourier transform infrared, and ¹H NMR and ¹³C NMR spectra. The mesomorphic properties of elastomers were investigated with differential scanning calorimetry, thermogravimetric analysis, polarizing optical microscopy, and X‐ray diffraction measurements. The influence of the content of the crosslinking unit on the phase behavior of the elastomers was examined. Monomer M₁ showed a cholesteric phase, and M₂ displayed smectic and nematic phases. The elastomers containing <15 mol % of the crosslinking units revealed reversible mesomorphic phase transition, wide mesophase temperature ranges, and high thermal stability. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3315–3323, 2005     

Stilbene‐containing polyactylenes: Molecular design,synthesis, and relationship between molecular structure and NLO properties

Polyacetylenes ( P1–P4 ) containing different stilbene groups, ? [(CH?C) ? Ph? CH?CH? Ph? R]_n? (R?OC_mH_2m+1 (m = 4 ( P1 ), 10 ( P2 ), 16 ( P3 )), or NO₂ ( P4 )) were designed and synthesized, respectively, using [Rh(nbd)Cl]₂ as a catalyst. Their structures and properties were characterized and evaluated by FTIR, ¹H‐NMR, ¹³C‐NMR, GPC, and UV, PL, respectively. The optical limiting and nonlinear optical properties were investigated by using a frequency doubled, Q‐switched, mode‐locked Continuum ns/ps Nd:YAG laser system and their optical limiting mechanism was discussed. It is surprising to see that the stilbene pendants endow the polyacetylenes with a high thermal stability (T_d ≥ 270 °C), novel optical limiting properties and large third‐order nonlinear optical susceptibilities (up to 4.61 × 10^?10 esu). The optical limiting mechanism is mainly originated from reverse saturable absorption of molecules. In addition, it is found that the polymer with electron accepted NO₂ moiety exhibits better optical properties than that with electron donated alkoxy group because of larger π electron delocalization and dipolar effect. The strong interaction between stilbene pendants and the polyene main chain significantly results in red‐shift of fluorescence emitting peak. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4529–4541, 2008