Synthesis and optical properties of novel soluble and optically transparent semifluorinated poly (ether imide)s

A fluorinated diamine monomer containing flexible ether linkage and bulky trifluoromethyl substituents, namely, bis(4‐amino‐2‐trifluoromethylphenyl) ether (a), is employed to react with nonfluorinated 1,4‐bis(3,4‐dicarboxyphenoxy) benzene dianhydride (3) and CF₃‐free 2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl] propane dianhydride (4), respectively, to prepare 2 novel soluble and optically transparent semi‐fluorinated poly (ether imide)s (PEIs; 3a and 4a). Compared with the corresponding PEIs based on nonfluorinated 4,4′‐diaminodiphenyl ether (b) and CF₃‐free pyromellitic dianhydride (5), the novel semifluorinated PEIs 3a and 4a not only display better solubility in some organic solvents and higher optical transparency with cutoff absorption wavelength (λ₀) below 370 nm but also maintain outstanding mechanical properties and thermal stability. 3a and 4a have tensile strength beyond 80 MPa and possess glass‐transition temperatures (T_g) beyond 210°C, coupled with the temperatures of 5% weight loss (T_5%) exceeding 500°C. It is also found that 3a and 4a exhibit contact angles against water beyond 110° and water absorptions below 0.8% together with dielectric constants less than 3.2.     

Organosoluble and colorless fluorinated poly(ether imide)s from 1,2‐bis(3,4‐dicarboxyphenoxy)benzene dianhydride and trifluoromethyl‐substituted aromatic bis(ether amine)s

A series of novel aromatic poly(ether imide)s (PEI) containing ortho‐catenated phenylene rings and pendant trifluoromethyl group have been prepared from 1,2‐bis(3,4‐dicarboxyphenoxy)benzene dianhydride (1) with seven trifluoromethyl‐substituted aromatic bis(ether amine)s ( 2a‐g ) via a conventional two‐stage process that included ring‐opening polyaddition to form the poly(amic acid)s followed by chemical imidization to the polyimides. These PEIs had inherent viscosities in the range of 0.45–1.17 dL/g that corresponded to weight–average and number–average molecular weights (by gel‐permeation chromatography) of 42,000–102,000 and 28,500–67,500, respectively. All the PEIs were readily soluble in many organic solvents and could be solution‐cast into transparent, flexible, and strong films. These films were essentially colorless; they had a very low yellowness index of 4.34–6.55 and an UV–vis absorption cut‐off wavelength at 361–370 nm. The PEIs exhibited moderate‐to‐high glass‐transition temperatures (T_g) in the range of 185–270 °C, softening temperatures (T_s) in the range of 184–275 °C, and 10% weight loss temperatures higher than 466 °C in nitrogen or in air. They also showed low moisture absorptions of 0.49–0.70% and low dielectric constants of 2.78–3.26 (measured at 10 kHz). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3092–3102, 2006     

Novel organosoluble and thermally stable polyetherimides based on a new dianhydride monomer 2,6-bis-(isobenzofuran-1,3-dione-5-yl)pyridine (BIDP)

A series of organosoluble and thermally stable polyetherimides (PEIs) containing pyridine moieties and flexible ether linkages are synthesized based on a new aromatic dianhydride, 2,6-bis-(isobenzofuran-1,3-dione-5-yl)pyridine (BIDP). The prepared polymers are soluble in common aprotic solvents such as DMF, DMSO, NMP and DMAc at room temperature. Thermal behavior of the PEIs is studied by thermogravimetric analysis/dynamic thermal analysis (TGA-DTA). The inherent viscosities of the PEI solutions are in the range of 0.61–0.70 dL/g (in DMSO with a concentration of 0.25 g/dL at 25±0.5°C). The metal ion uptake capacity of PEI-4 for Co(II) removal from aqueous solutions is shown to be remarkably higher than that of the polyimide (PI) with a similar structure reported earlier.     

Synthesis of a new class of triphenylamine‐containing poly(ether‐imide)s for electrochromic applications

A novel triphenylamine (TPA)‐containing bis(ether anhydride) monomer, namely 4,4′‐bis(3,4‐dicarboxyphenoxy)triphenylamine dianhydride, was synthesized and reacted with various aromatic diamines leading to a series of new poly(ether‐imide)s (PEI). Most of these PEIs were soluble in organic solvents and could be easily solution cast into flexible and strong films. The polymer films exhibited good thermal stability with glass‐transition temperatures in the range 211–299 °C. The polymer films exhibited reversible electrochemical processes and stable color changes (from transparent to navy blue) with high coloration efficiency and contrast ratio upon electro‐oxidation. During the electrochemical oxidation process, a crosslinked polymer structure was developed due to the coupling reaction between the TPA radical cation moieties in the polymer chains. These polymers can be used to fabricate electrochromic devices with high coloration efficiency, high redox stability, and fast response time. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 825–838     

Poly(ether imide)s with tailored end groups

Poly(ether imide) (PEI) from polycondensation of 2,2-bis[4-(3,4-dicarboxyphenoxy) phenyl] propane dianhydride (BPADA) and m-phenylenediamine (mPD) is a type of high-temperature engineering thermoplastics that have high glass transition temperature and outstanding mechanical properties. Owing to its wide use in many fields including automotive, aircraft, and electronics, the research of PEI has surged in the last few decades. As science and technology continue to progress rapidly, there is a growing demand for PEIs with better properties. Although a few approaches have successfully improved the properties of PEI, it is recognized that these approaches require complex procedures and are uneconomical. Contrastingly, end-group modification of PEI is highly effective, simple, and economical. Over the last few years, our group has extensively studied the methods for improving the properties of PEI through end-group modification. The end-group moieties and polymer blocks introduce multiple hydrogen bonding, electrostatics, and microphase separation to PEI. In this article, we first classify the end groups based on their characteristics. Then, we compare their effects on the properties of PEIs, including thermal, rheological, mechanical, optical, flame-retardant, and morphological, and discuss the roots of these effects. The in-depth comparisons and discussion generate principles to guide the synthesis of PEIs with tailored properties by modifying the end groups. This timely article will provide insights into the synthesis of other novel high-temperature polymers and entice endeavors to develop novel end groups.     

Synthesis and properties of novel triptycene‐based polyimides

Two new triptycene‐containing bis(ether amine)s, 1,4‐bis(4‐aminophenoxy)triptycene ( 4 ) and 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)triptycene ( 6 ), were synthesized, respectively, from the nucleophilic chloro‐displacement reactions of p‐chloronitrobenzene and 2‐chloro‐5‐nitrobenzotrifluoride with 1,4‐dihydroxytriptycene in the presence of potassium carbonate, followed by palladium‐catalyzed hydrazine reduction of the dinitro intermediates. The bis(ether amine)s were polymerized with six commercially available aromatic tetracarboxylic dianhydrides to obtain two series of novel triptycene‐based polyimides 8a – f and 9a – f by using a conventional two‐step synthetic method via thermal and chemical imidizations. All the resulting polyimides exhibited high enough molecular weights to permit the casting of flexible and strong films with good mechanical properties. Incorporation of trifluoromethyl groups in the polyimide backbones improves their solubility and decreases their dielectric constants. The fluorinated polyimides 9d and 9f derived from diamine 6 with 4,4′‐oxydiphthalic anhydride and 2,2‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), respectively, could afford almost colorless thin films. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Syntheses and properties of organosoluble poly(ether imide)s from 1,1‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]cyclohexane dianhydride and aromatic diamines

A bis(ether anhydride) monomer, 1,1‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl]cyclohexane dianhydride ( IV‐A ), was synthesized from the nitro displacement of 4‐nitrophthalodinitrile by the phenoxide ion of 1,1‐bis(4‐hydroxyphenyl)cyclohexane ( I‐A ), followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and dehydration of the resulting bis(ether acid). A novel series of organosoluble poly(ether imide)s ( VI _a–i )(PEIs) bearing cyclohexylidene cardo groups was prepared from the bis(ether anhydride) IV‐A with various aromatic diamines V _a–i via a conventional two‐stage process. The PEIs had inherent viscosities in the range of 0.48–1.02 dL/g and afforded flexible and tough films by solution‐casting because of their good solubilities in organic solvents. Most PEIs showed yield points in the range of 89–102 MPa at stress‐strain curves and had tensile strengths of 78–103 MPa, elongations at breaks of 8–62%, and initial moduli of 1.8–2.2 GPa. The glass‐transition temperatures (T_g's) of these PEIs were recorded between 200–234 °C. Decomposition temperatures of 10% weight loss all occurred above 490 °C in both air and nitrogen atmospheres, and their residues were more than 43% at 800 °C in nitrogen atmosphere. The cyclohexane cardo‐based PEIs exhibited relatively higher T_g's, better solubilities in organic solvents, and better tensile properties as compared with the corresponding Ultem® PEI system. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 788–799, 2001     

Dielectric properties of oxydianiline‐based polyimide thin films according to the water uptake

For polyimide thin films, the dielectric properties were investigated with the capacitance and optical methods. The dielectric constants of the 4,4′‐oxydianiline (ODA)‐based polyimide thin films varied from 2.49 to 3.10 and were in the following decreasing order: 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA)–ODA > 1,2,4,5‐benzenetetracarboxylic dianhydride (PMDA)–ODA > 4,4′‐hexafluoroisopropylidene diphthalic dianhydride (6FDA)–ODA. According to the absorption of water, the diffusion coefficients in the films varied from 4.8 × 10^?10 to 7.2 × 10^?10 cm²/s and were in the following increasing order: BPDA–ODA < PMDA–ODA < 6FDA–ODA. The dielectric constants and diffusion coefficients of the polyimides were affected by the morphological structures, including the molecular packing order. However, because of the water uptake, the changes in the dielectric constants in the polyimide thin films varied from 0.49 to 1.01 and were in the following increasing order: BPDA–ODA < 6FDA–ODA < PMDA–ODA. Surprisingly, 6FDA–ODA with bulky hexafluoroisopropylidene groups showed less of a change in its dielectric constant than PMDA–ODA. The total water uptake for the polyimide thin films varied from 1.43 to 3.19 wt % and was in the following increasing order: BPDA–ODA < 6FDA–ODA < PMDA–ODA. This means that the changes in the dielectric constants in the polyimide thin films were significantly related to the morphological structure and hydrophobicity of hexafluoroisopropylidene groups. Therefore, the morphological structure and chemical affinity in the polyimide thin films were important factors in controlling the dielectric properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2190–2198, 2002     

Self-Crosslinkable poly(arylene ether)s containing pendent phenylenetriazene groups

Self-crosslinkable poly(arylene ether)s 6 , and 8 , containing pendent triazene groups were prepared by nucleophilic substitution reaction of poly(arylene ether)s 5 , and 7 , respectively, with 1-[4-(4-hydroxyphenoxy)phenylene]triazenes, 4 , in the presence of potassium carbonate in N,N-dimethylacetamide. A series of triazenes 4 containing various substituents have been synthesized. Self-crosslinkable polymer 6e containing phenyl-substituted triazene pendants can be crosslinked at 215°C, which is about 40°C lower than the glass transition temperature of the virgin base polymer 5 . The degree of crosslinking can be tailored by varying the concentration of the pendent phenylenetriazene groups in the polymer. After curing, the flexible polymer films (ca. 10 μm thick) exhibit high gel contents, increased glass transition temperatures, improved resistance to organic solvents, and little change in dielectric constant and thermal stability. These self-crosslinkable poly(arylene ether)s are potential candidates for electronic applications. © 1994 John Wiley & Sons, Inc.     

Synthesis and Properties of New Fluorinated Polyimides Derived from an Unsymmetrical and Noncoplanar Diamine

A new unsymmetrical and noncoplanar diamine containing trifluoromethyl and trimethyl groups, 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐2,3,5‐trimethylbenzene ( 2 ), was synthesized using 2,3,5‐trimethylhydroquinone and 2‐chloro‐5‐nitrobenzotrifluoride as starting materials. A series of fluorinated poly(ether imide)s (PEIs) ( 4a–4d ) were prepared from diamine 2 with four aromatic dianhydrides via a one‐step high‐temperature polycondensation procedure. The obtained PEIs were readily soluble in most organic solvents and could be solution‐cast into flexible and strong films. The resulting thin films exhibited light color and good optical transparency with a cutoff wavelength of 356–376 nm. They also displayed good thermal stability with glass transition temperatures (T_g) above 281°C, 10% weight loss temperatures in the range of 482–486°C, and the weight residue more than 55% at 800°C in nitrogen. Moreover, they revealed low dielectric constants (2.77–2.93 at 1 MHz) and low moisture absorptions (0.41%–0.57%).     

New light‐colored poly(ether imide)s based on 2,5‐di‐tert‐butylhydroquinone bis(ether anhydride) and aromatic diamines

A series of poly(ether imide)s (PEIs), III _a–k , with light color and good physical properties were prepared from 1,4‐bis(3,4‐dicarboxypheoxy)‐2,5‐di‐tert‐butylbenzene dianhydride ( I ) with various aromatic diamines ( II _a–k ) via a conventional two‐stage procedure that included a ring‐opening polyaddition to yield poly(amic acid)s (PAA), followed by thermal imidization to the PEI. The intermediate PAA had inherent viscosities in the range of 1.00–1.53 dL g^?1. Most of the PEIs showed excellent solubility in chlorinated solvents such as dichloromethane, chloroform, and m‐cresol, but did not easily dissolve in dimethyl sulfoxide and amide‐type polar solvents. The III series had tensile strengths of 96–116 MPa, an elongation at break of 7–8%, and initial moduli of 2.0–2.5 GPa. The glass‐transition temperatures (T_g) and softening temperatures (T_s's) of the III series were recorded between 232 and 285 °C and 216–279 °C, respectively. The decomposition temperatures for 10% weight loss all occurred above 511 °C in nitrogen and 487 °C in air. The III series showed low dielectric constants (2.71–3.54 at 1 MHz), low moisture absorption (0.18–0.66 wt %), and was light‐colored with a cutoff wavelength below 380 nm and a low yellow index (b^*) values of 7.3–14.8. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1270–1284, 2005     

Synthesis and properties of fluorinated polyimides. 1. Derived from novel 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl

A new diamine monomer, 4,4″‐bis(aminophenoxy)‐3,3″‐trifluoromethyl terphenyl (ATFT) was synthesized that led to a number of novel fluorinated polyimides by solution as well as thermal imidization routes when reacted with different commercially available dianhydrides like pyromellatic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), or 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane (6FDA). The polyimides ATFT/BTDA and ATFT/6FDA derived from both routes were soluble in several organic solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide, and dimethyl sulfoxide. The polyimide ATFT/PMDA was only soluble in N‐methylpyrollidone. The polyimide films had low water absorption of 0.3–0.7%, low dielectric constants of 2.72–3.3 at 1 Hz, refractive indices of 1.594–1.647 at 589.3 nm, and optical transparency >85%. These polyimides showed very high thermal stability with decomposition temperatures (5% weight loss) up to 532 °C in air and good isothermal stability; only 7% weight loss occurred at 400 °C after 7 h, and less than 0.6% weight loss was observed at 315 °C for 5 h. Transparent thin films of these polyimides exhibited tensile strengths up to 112 MPa, a modulus of elasticity up to 3.05 GPa, and elongation at break up to 21% depending on the repeating unit structure. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1016–1027, 2002     

Thermally polymerizable bisaryloxy-bisimido-bisphthalonitriles containing dimethylsilane,hexafluoroisopropylidene, ether,and keto groups: Synthesis,characterization, and NMR study

A proton-NMR study of the condensation reaction (step 1) of 4-(3′-aminophenoxy)phthalonitrile (4-3′APPN) ( I ) in an aprotic solvent with various aromatic dianhydrides demonstrated the formation of the corresponding bisamic acid within 5–10 min. There was no effect of the electron affinity of the used aromatic dianhydrides on the time of the condensation reaction and also no charge-transfer complex formation was indicated. Proton-NMR study of the synthesized bisaryloxy-bisimido-bisphthalonitriles at 250.1 MHz has revealed general findings for their NMR characterization. The coupling constant (J) value for the ortho-coupled protons of the phthalonitrile ring of the 4–3′-APPN portion is 8.8 ± 0.05 Hz and that for the ortho-coupled protons of the aminophenoxy ring of 4–3′-APPN is 8.1 ± 0.05 Hz. The coupling constant (J) values for ortho-coupled protons of the dianhydride portion range from 8.1 to 7.5 Hz. Various thermally polymerizable bisaryloxybisimido-bisphthalonitriles (BBBP) ( X, XI, XII , and XIII ) containing dimethylsilane, hexafluoroisopropylidene, ether, and keto groups, suitable for the development of thermooxidative stable, void-free composites, were synthesized by two methods. In method 1,4–3′-APPN ( I ) in N,N-dimethylacetamide (DMAC) was condensed (step 1) with bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride (SIDA) ( II ), 4, 4′-hexafluoroisopropylidenediphthalic anhydride (6FDA) ( III ), bis(3,4-dicarboxyphenyl)ether dianhydride (ODPA) ( IV ), and 3,4,3′,4′-benzophenonetetracarboxylic dianhydride (BTDA) ( V ), respectively, to give the corresponding bisamic acids. Thermal cyclodehydration of the intermediate bisamic acid at 160°C gave the bisphthalonitriles. In method 2, the second step of thermal cyclodehydration was performed in situ in refluxing toluene. The characterization of the synthesized bisaryloxy-bisimido-bisphthalonitriles (BBBP) was performed using FT-IR, ¹H-NMR, ¹³C-NMR, mass spectroscopy, and elemental analysis. A preliminary study indicated that thermal-polymerization of these bisphthalonitriles (BBBP) gave tough, thermosetting polymers, useful for high-temperature applications. © 1993 John Wiley & Sons, Inc.     

Synthesis and characterization of polyimides from bis(3‐aminophenyl)‐4‐(1‐adamantyl)phenoxyphenyl phosphine oxide

A novel diamine, bis(3‐aminophenyl)‐4‐(1‐adamantyl)phenoxyphenyl phosphine oxide (mDAATPPO), was synthesized via the Williamson ether reaction of 4‐(1‐adamantyl)phenol and bis(3‐nitrophenyl)‐4‐fluorophenyl phosphine oxide, followed by reduction. The phenol group was prepared by the Friedel–Crafts reaction of 1‐bromoadamantane and phenol, whereas the phosphine oxide group was synthesized by the Grignard reaction of 1‐bromo‐4‐fluorobezene and diphenyl phosphinic chloride, followed by nitration. The monomer and its intermediate compounds were characterized with Fourier transform infrared, NMR, and melting‐point apparatus. The monomer was then used to prepare polyimides with 2,2‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride, 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride, 4,4′‐oxydiphthalic dianhydride, and pyromellitic dianhydride by the conventional two‐step synthesis: the preparation of poly(amic acid) followed by solution imidization. The molecular weights of the polyimides were controlled to 20,000 g/mol by off‐stoichiometry, and the synthesized polyimides were characterized with Fourier transform infrared, NMR, gel permeation chromatography, thermogravimetric analysis, and differential scanning calorimetry. In addition, the solubility, intrinsic viscosity, dielectric constant, and birefringence of the polyimides were evaluated. Novel polyimides with mDAATPPO exhibited good solubility, high glass‐transition temperatures (290–330 °C), excellent thermal stability (>500 °C), low dielectric constants (2.77–3.01), low refractive indices, and low birefringence values (0.0019–0.0030). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2567–2578, 2006     

Organosoluble,low dielectric constant and highly transparent fluorinated pyridine-containing poly(ether imide)s derived from new diamine: 4-(4-trifluoromethyl)phenyl-2,6-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]pyridine

A new aromatic diamine, 4-(4-trifluoromethyl)phenyl-2,6-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]pyridine, was synthesized by a modified Chichibabin reaction of 4-(4-nitro-2-trifluoromethylphenoxy)acetophenone with 4-triflouromethylbenzaldehyde, followed by catalytic reduction. A series of fluorinated pyridine-containing aromatic poly(ether imide)s (PEIs) were prepared from the diamine monomer with various aromatic dianhydrides via conventional two-step thermal imidization method. The resulting PEIs had inherent viscosities values of 0.68–0.90 dL/g, and could be cast and thermally converted into transparent, flexible, and tough polymer films. These PEIs were predominantly amorphous, had good solubility in common solvents such as NMP, DMAc and m-cresol at room temperature, and displayed excellent thermal stability with the glass transition temperatures of 258–315?°C, the temperatures at 5% weight loss of 550–585?°C, and the residue of higher than 55% at 750?°C in nitrogen. Moreover, the PEIs films showed outstanding mechanical properties with tensile strengths of 74.8–103.5?MPa, tensile moduli of 1.08–1.45?GPa, and elongations at break of 10.6–24.4%. These PEIs also exhibited low dielectric constants of 2.81–2.98 (1?MHz) and water uptake 0.39–0.68%, as well as high optical transparency with the UV cutoff wavelength in the 350–378?nm range and the wavelength of 80% transparency in the range of 412–510?nm.     

Adhesive and dielectric properties of novel polyimides with bis(3,3′-aminophenyl)-2,3,5,6-tetrafluoro-4-trifluoromethyl phenyl phosphine oxide (mDA7FPPO)

Polyimides with a low dielectric constant and excellent adhesion were prepared from a diamine containing phosphine oxide and fluorine groups, bis(3,3′-aminophenyl-2,3,5,6-tetrafluoro-4-trifluoromethyl phenyl phosphine oxide (mDA7FPPO), and rigid-rod type dianhydride containing fluorine groups, such as 3,6-di(3′,5′-bis(trifluoromethyl)-phenyl)pyromellitic dianhydride (12FPMDA). The polyimides were synthesized via the known two-step process, preparation of poly(amic-acid) followed by solution imidization, and characterized by FT-IR, NMR, DSC, TGA and TMA. In addition, their solubility, intrinsic viscosity, dielectric constant and adhesive property were also evaluated. For comparison, 3,6-di(4′-trifluoromethylphenyl) pyromellitic dianhydride (6FPMDA) and 3,6-diphenylpyromellitic dianhydride (DPPMDA) were also utilized. The prepared polyimides exhibited high T_g (276-314 °C), excellent thermal stability (>500 °C in air), good adhesive property (104.7-126.3 g/mm), good solubility, and very low dielectric constant (2.34-2.89).     

Development of Poly(Phenylene)-Based Materials for Thin Film Applications: Optical Waveguides and Low Dielectric Materials

Abstract

We have synthesized and evaluated poly(phenylene)-based materials made via spin-coatable polymeric precursors for such thin film applications as optical waveguides and low dielectric materials. Poly(phenylene) precursors were prepared by radical polymerization of cyclohexadiene-1, 2-diol derivatives containing various leaving groups. The precursors were converted into poly(phenylene) either by curing at 300°C or by deep-UV exposure in the presence of a photoacid generator. Poly(phenylene) has a number of desirable properties including good near-IR transmission, low dielectric constant, thermal and environmental stability, low water absorption, and ease of pattern fabrication using microlithographic techniques. Copolymer precursors based on 1,2-diaceto-3,5-cyclohexadiene and styrene derivatives as well as copolymers with Nsubstituted maleimide derivatives were prepared by radical copolymerization. The copolymer precursors were converted into poly(phenylene) copolymers either by annealing at 300°C or by deep-UV exposure in the presence of a photoacid generator. The results of this study indicate that copolymerization allows the incorporation of comonomers that can control dielectric and optical properties as well as glass transition temperature.     

Synthesis and characterization of photocrosslinkable,side‐chain,second‐order nonlinear optical poly(ester imide)s with great film‐forming ability and long‐term dipole orientation stability

A series of photocrosslinkable, side‐chain, second‐order nonlinear optical (NLO) poly(ester imide)s (PEIs) based on a chromophore‐containing dianhydride, 2,2′‐{4‐[(4‐nitrophenyl)‐azo]phenyl}iminobis(ethyl benzene‐1,2‐dicarboxylic acid anhydride‐4‐carboxylate), benzophenone‐3,3′,4,4′‐tetracarboxylic dianhydride, and 4,4′‐diamino‐3,3′‐dimethyl diphenylmethane were prepared. The resulting PEIs exhibited many useful physical characteristics, such as good organosolubility, excellent film‐forming properties, high glass‐transition temperatures (186–229 °C), and high thermal decomposition temperatures. The electrooptic coefficient value of PEI3 at 650 nm was 11.5 pm/V, and high long‐term stability of the NLO chromophore alignment in the poled PEI3 film at 120 °C was observed. The temporal stability of the dipole orientation at 150 °C was further enhanced by ultraviolet irradiation because of photocrosslinking. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 303–312, 2003     

Melt-polymerizable bisimido-bisphthalonitriles containing silicon,fluoro, and ether groups: Synthesis,characterization, and NMR study

Various melt-polymerizable bisimido-bisphthalonitrile polymer precursors were synthesized by the reaction of 4-aminophthalonitrile (4-APN) with bis(3,4-dicarboxyphenyl) dimethylsilane dianhydride (SIDA), 4,4′-hexafluoroisopropylidene diphthalic anhydride (6FDA), bis(3,4-dicarboxyphenyl)ether dianhydride (ODPA), and 3,3′, 4,4′-tetracarboxylichenzophen+ne dianhydride (BTDA) in an aprotic solvent. The synthesized monomers showed crystalline melting at 269 and 271°C. Elemental analysis, differential thermal analysis (DTA), infrared (IR), nuclear magnetic resonance (¹H-NMR) and mass spectral studies were carried out to characterize the synthesized monomers. Thermogravimetric analysis (TGA) of the synthesized monomers showed their thermal stability at 410–400°C. A detailed study and NMR investigation of the first step of condensation reaction was carried out and indicated the formation of a transient charge transfer complex. Thermal cyclization of the formed intermediate, however, gave the required monomers. A preliminary study demonstrated that melt-polymerization of the synthesized monomers gave thermallystable, tough polymers.     

Synthesis and characterization of novel polyimide from bis‐(3‐aminophenyl)‐4‐(trifluoromethyl)phenyl phosphine oxide

A novel diamine, bis‐(3‐aminophenyl)‐4‐(trifluoromethyl)phenyl phosphine oxide (mDA3FPPO), containing phosphine oxide and fluorine moieties was prepared via the Grignard reaction from an intermediate, 4‐(trifluoromethyl)phenyl diphenyl phosphine oxide, that was synthesized from diphenylphosphinic chloride and 4‐(trifluoromethyl)bromobenzene, followed by nitration and reduction. The monomer was characterized by Fourier transform infrared (FTIR), ¹H NMR, ³¹P NMR, ¹⁹F NMR spectroscopies; elemental analysis; melting point measurements; and titration and was used to prepare polyimides with a number of dianhydrides such as pyromellitic dianhydride (PMDA), 5,5′‐[2,2,2‐trifluoro‐1‐(trifluoromethyl)ethyliden]‐bis‐1,3‐isobenzofuranedione (6FDA), 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA), and 4,4′‐oxydiphthalic dianhydride (ODPA). Polyimides were synthesized via a conventional two‐step route; preparation of polyamic acids, followed by solution imidization, and the molecular weight were controlled to 20,000 g/mol. Resulting polyimides were characterized by FTIR, NMR, DSC, and intrinsic viscosity measurements. Refractive‐index, dielectric constant, and adhesive properties were also determined. The properties of polyimides were compared with those of polyimides prepared from 1,1‐bis‐(4‐aminophenyl)‐1‐phenyl‐2,2,2‐trifluoroethane (3FDAm) and bis‐(3‐aminophenyl) phenyl phosphine oxide (mDAPPO). The polyimides prepared from mDA3FPPO provided high glass‐transition temperatures (248–311 °C), good thermal stability, excellent solubility, low birefringence (0.0030–0.0036), low dielectric constants (2.9–3.1), and excellent adhesive properties with Cu foils (107 g/mm). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3335–3347, 2001