New rigid‐rod and strictly alternating poly(benzoxazole‐imide)s containing methyl‐substituted p‐phenylene units in the main chain

A series of new strictly alternating poly(o‐hydroxy amide‐imide)s with high molecular weight were synthesized by low‐temperature solution polycondensation from the preformed imide ring and methyl‐ or dimethyl‐substituted p‐phenylene‐containing diacyl chlorides of 2,5‐bis(trimellitimido)toluene or 1,4‐bis(trimellitimido)‐2,5‐dimethylbenzene and three bis(o‐amino phenol)s. All the poly(o‐hydroxy amide‐imide)s are readily soluble in a variety of organic solvents such as N‐methyl‐2‐pyrrolidone (NMP) and N,N‐dimethylacetamide (DMAc). Transparent and flexible films of these polymers were cast from NMP solutions. The tensile strength of the films ranges from 90–105 MPa and elongation at break from 7–12%. Subsequent thermal cyclodehydration of the poly(o‐hydroxy amide‐imide)s afforded novel rigid‐rod and strictly alternating poly(benzoxazole‐imide)s. They exhibit glass transition temperatures in the range of 316–345°C and are stable up to 500°C in air or nitrogen, with a 10% weight loss temperature in nitrogen ranging from 550–585°C.     

Novel Organosoluble Poly(amide‐imide)s Derived from Kink Diamine Bis[4‐(4‐trimellitimidophenoxy)phenyl]‐diphenylmethane. Synthesis and Characterization

A new kink diimide‐dicarboxylic acid, 2,2‐bis[4‐(4‐trimellitimidophenoxy)phenyl]diphenylmethane (BTPDM), was synthesized by the condensation reaction of bis[4‐(4‐aminophenoxy)phenyl]diphenylmethane (BAPDM ) with trimellitic anhydride. A series of new poly(amide‐imide)s were prepared by direct polycondensation of BTPDM and various aromatic diamines in N‐methyl‐2‐pyrrolidinone (NMP) using triphenyl phosphite and pyridine as condensing agents. The polymers were produced in high yield revealing moderate to high inherent viscosities of 0.80–0.89 dL·g^–1. Wide‐angle X‐ray diffractograms revealed that the polymers are amorphous. Most of the polymers exhibit good solubility and could be readily dissolved in various solvents such as NMP, N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide, dimethyl sulfoxide, pyridine, cyclohexanone and tetrahydrofuran. These poly(amide‐imide)s have glass transition temperatures between 244–248°C and show 10% weight loss in the range of 453–469°C under a nitrogen atmosphere. The tough polymer films, obtained by casting from DMAc solution, had tensile strengths ranging between 82 and 95 MPa and tensile moduli ranging between 1.7 and 1.9 GPa.     

Fluorinated Aromatic Polyamides and Poly(amide‐imide)s: Synthesis and Properties

Summary: A CF₃‐containing diamine, 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)biphenyl ( I ), was synthesized from 4,4′‐biphenol and 2‐chloro‐5‐nitrobenzotrifluoride. The imide‐containing diacids ( V_a‐b and VI_a‐l ) were prepared by condensation reaction of amino acids, aromatic diamines and trimellitic anhydride. Then, a series of soluble aromatic polyamides ( VII_a‐f ) and poly(amide‐imide)s ( VIII_a‐b and IX_a‐l ) were synthesized from diamine I with various aromatic diacids ( II_a‐f ) and the imide‐containing diacids ( V_a‐b and VI_a‐l ) via direct polycondensation with triphenyl phosphate and pyridine. Aromatic polyamides and poly(amide‐imide)s had inherent viscosities of 0.60–0.85 dL/g and 0.52–1.44 dL/g, respectively. All synthesized polymers showed excellent solubility in amide‐type solvents such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide (DMAc) and N‐dimethylforamide and afford transparent and tough films by DMAc solvent casting. These polymer films had tensile strengths of 87–135 MPa, elongations to break of 8–22%, and initial moduli of 2.0–3.0 GPa. Glass transition temperature of these polymers were in the range of 259–317 °C, and the poly(amide‐imide)s had better thermal stability than aromatic polyamides. In comparison with the isomeric X series, the IX series exhibited less coloring and showed a lower b* (yellowness index) values than the corresponding IX series.

     

Soluble and Colorless Poly(ether‐imide)s Based on a Benzonorbornane Bis(ether anhydride) and Trifluoromethyl‐Substituted Aromatic Bis(ether‐amine)s

Summary: A series of organosoluble and colorless fluorinated poly(ether imide)s ( IV_a‐g ) were prepared from 3,6‐bis(3,4‐dicarboxyphenoxy)benzonorbornane dianhydride ( I ) and various trifluoromethyl (CF₃)‐substituted aromatic bis(ether amine)s II_a‐g by a standard two‐step process with thermal and chemical imidization of poly(amic acid) precursors. These poly(ether imide)s had inherent viscosities of 1.02–1.28 dL · g^?1 and showed excellent solubility in many organic solvents. They could be solution‐cast into transparent, flexible, and tough films with good mechanical properties. These films were virtually colorless, with an ultraviolet‐visible absorption edge of 372–381 nm and a very low b* value (a yellowness index) of 10.8 to 18.2. The glass‐transition temperatures (T_g) and softening temperatures (T_s) were recorded between 216–292 °C and 209–285 °C, respectively. The decomposition temperature for 10% weight loss all occurred above 472 °C in nitrogen and 481 °C in air, and the char yields at 800 °C in nitrogen were more than 51%. They also showed low dielectric constants of 2.84–3.58 (1 MHz) and moisture absorptions in the range of 0.05–0.19%. In comparison with analogous V series poly(ether imide)s without the CF₃ substituents, the IV series ones showed better solubility, lower color intensity, and lower dielectric constants.

A novel series of fluorinated poly(ether imide)s.     

Influence of Chemical Structure on the Refractive Index of Imide‐Type Polymers

The influence of different substituents on the optical properties of poly(amide imide)s and polyimides is systematically investigated. All of the polymers exhibit good solubility and film‐forming ability, high thermal stability, and glass transition temperatures of 162–209 °C for poly(amide imide)s and of 209–274 °C for polyimides. The optical transmittance of the films at 450 nm is above 80% for all the studied polyimides and poly(amide imide)s containing benzonitrile units linked in the 2,6‐position. The values of refractive index for poly(amide imide)s are in the range of 1.623–1.748 and for polyimides in the domain of 1.672–1.768.

     

Thermally Stable,Organosoluble, and Colorless Poly(ether imide)s Having Ortho‐Linked Aromatic Units in the Main Chain and Trifluoromethyl Pendent Groups

Summary: A novel series of aromatic poly(ether imide)s (PEIs) IVa–h containing ortho‐linked aromatic units and pendent trifluoromethyl (CF₃) groups were prepared from 2,3‐bis(3,4‐dicarboxyphenoxy)naphthalene dianhydride ( I ) with various CF₃‐substituted aromatic bis(ether amine)s IIa–h via a conventional two‐stage process including ring‐opening polyaddition to form the poly(amic acid)s followed by either chemical or thermal imidization to the PEIs. The inherent viscosities of PEIs IVa–h were in the range of 0.43–0.86 dL · g^?1 that corresponded to weight‐average and number‐average molecular weights (by gel permeation chromatography) of 36 000–73 000 and 23 000–51 000, respectively. All the IV series were highly soluble in several organic solvents and could be solution‐cast into transparent, flexible, and strong films. These films were essentially colorless; their cut‐off wavelengths were between 368 and 377 nm and a very low b* value (a yellowness index) ranging from 4.1 to 5.5. They had useful levels of thermal stability associated with moderately high‐glass transition temperatures (208–281 °C), 10% weight‐loss temperatures in excess of 492 °C, and char yields at 800 °C in nitrogen higher than 51%. They also showed low water uptakes of 0.25–0.48% and low dielectric constants of 3.06–3.67 at 10 kHz. For a comparative study, a series of structurally similar, non‐fluorinated PEIs Va–h from dianhydride I and bis(ether amine)s II′a–h were also prepared and characterized.

A novel series of aromatic poly(ether imide)s (PEIs) IVa–h .     

Synthesis and Characterization of New Organosoluble Polyamides and Polyimides Based on 2,2‐Bis[4‐ (4‐aminophenoxy)‐3,5‐dimethylphenyl]‐ hexafluoropropane

A new hexafluoro‐containing diamine monomer, 2,2‐bis[4‐(4‐aminophenoxy)‐3,5‐dimethylphenyl]hexafluoropropane ( TBAPHP ), was synthesized in three steps, starting from hexafluoroacetone sesquihydrate and 2,6‐xylenol. The monomer was reacted with various aromatic dicarboxylic acids and tetracarboxylic dianhydrides to produce a series of polyamides and polyimides, respectively. The polyamides were prepared under Yamazaki reaction conditions. The polyimides were prepared by a two‐stage procedure that included a ring‐opening polyaddition yielding poly(amic acid)s, followed by a cyclodehydration to polyimides. The obtained polymers had inherent viscosities of 0.52–0.82 dL·g^–1. All of the polymers dissolved in polar solvents, such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide, and N,N‐dimethylformamide. The polyimides derived from 4,4′‐oxydiphthalic anhydride and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride exhibited an excellent solubility and were dissolved in cyclohexanone, pyridine, tetrahydrofuran, and chloroform. These polymers showed glass transition temperatures of 231–301°C and decomposition temperatures at 10% weight loss ranging from 470 to 495°C in nitrogen and from 473 to 505°C in air. The tough and flexible polymer films obtained from solution casting showed tensile strengths of 78–96 MPa and tensile moduli of 2.0–2.4 GPa. Polymers containing methyl substituents had higher solubilities and T_g values than those without methyl substituents. In addition, the hexafluoroisopropylidene‐containing polymers exhibited a higher solubility and thermal stability than those containing isopropylidene units. UV‐visible absorption spectra revealed that the polyimides showed a better transparency than the polyamides.     

Multiresponsive Properties of Triple‐Shell Architectures with Poly(N,N‐diethylaminoethyl methacrylate), Poly(N‐vinylcaprolactam), and Poly(N,N‐dimethylaminoethyl methacrylate) as Building Blocks

Triple‐shell architectures, consisting of poly[(N,N‐diethylaminoethyl methacrylate)‐block‐(N‐vinylcaprolactam)‐block‐(N,N‐dimethylaminoethyl methacrylate)] triblock copolymers, are obtained by sequential reversible addition–fragmentation chain transfer polymerizations, using a terminal‐modified hyperbranched poly(β‐cyclodextrin) core as a macro chain transfer agent. UV‐vis spectroscopy results indicate that the triple‐shell architectures possess one pH response at pH 12.5 in aqueous solution at room temperature, followed by double‐temperature‐ responsiveness between 33 °C and 36 °C. The special multiresponsive properties are further confirmed by investigating the controlled release behavior of the resulting polymers using metronidazole as a model drug.     

Highly Organosoluble Polyimides with Pendent Cyclododecane Group: Synthesis and Characterization

A new bis(ether anhydride), 1,1‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl] cyclododecane dianhydride ( BDPCD ), was prepared in three steps starting from nitrodisplacement of 4‐nitrophthalonitrile with 2,2‐bis(4‐hydroxyphenyl) cyclododecane ( BHPC ), followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) ( BCPPC ) and subsequent dehydration of the resulting bis(ether diacid) ( BAPPC ). A series of new highly soluble poly(ether imide)s having tert‐butyl substituents, together with noncoplanar and pendent cardo groups were prepared from such bis(ether anhydride) ( BDPCD ) with various diamines by a conventional two‐stage synthesis including the polyaddition and chemical cyclodehydration. The resulting poly(ether imide)s had inherent viscosities in the range of 0.50–0.86 dL · g⁻¹. The GPC measurement revealed that the polymers exhibited number‐average and weight‐average molecular weight up to 63 000 and 115 000, respectively. All the polymers showed typical amorphous diffraction patterns. All of the poly(ether imide)s showed excellent solubility and were readily dissolved in various solvents such as N‐methyl‐2‐pyrrolidinone (NMP), N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide (DMF), pyridine, cyclohexanone and tetrahydrofuran. Most of the polymers could be dissolved in chloroform as high as 30 wt.‐% concentration. These polymers had glass transition temperatures (T_g) in the range of 230–262 °C. Thermogravimetric analysis (TGA) showed that all polymers were stable, with 10% weights loss recorded above 434 °C and 407 °C in nitrogen and air, respectively. These transparent, tough and flexible polymer films could be obtained by solution casting from the DMAc solution. These polymer films had tensile strengths in the range of 80–102 MPa and tensile moduli in the range of 1.7–2.0 GPa.

Synthesis route for BDPCD .     

Synthesis and properties of new aromatic noncyclic poly(imide-amide)s from N,N-bis(aminobenzoyl)anilines and aromatic dicarboxylic acids

Two dianilines containing the noncyclic N-phenylimide group, 4,4′- and 3,4′-diamino-(N,N-dibenzoylaniline), were synthesized as new diamine monomers. The low-temperature solution polycondensation of the diamines with aromatic dicarboxylic acid chlorides afforded poly(imide-amide)s with inherent viscosities of 0.14–0.44 dL/g. The noncyclic N-phenylimide unit in the diamines could be cleaved by nucleophilic attack at the amine function at high temperature. The noncyclic poly(imide-amide)s are soluble in polar solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and dimethyl sulfoxide. The polymers have glass transition temperatures and temperatures of 10% weight loss in air in the range of 195–265°C and 405–430°C, respectively.     

Enhancing Redox Stability and Electrochromic Performance of Polyhydrazides and Poly(1,3,4‐oxadiazole)s with 3,6‐Di‐tert‐butylcarbazol‐9‐yltriphenylamine Units

New polyhydrazides and poly(amidehydrazide)s bearing redox‐active carbazole and triphenylamine units were prepared. The resulting poly(1,3,4‐oxdiazole)s and poly(amide‐1,3,4‐oxadiazole)s had high glass‐transition temperatures (288–330 °C) and high thermal stability. The dilute solutions of all the hydrazide and oxadiazole polymers showed a weak–medium photoluminescence with emission maxima around 474–506 nm. The polymer films revealed two well‐defined and reversible redox couples upon electrochemical oxidation, together with interesting electrochromic behaviors. They showed enhanced redox‐stability and electrochromic performance. CV of the oxadiazole polymers also showed reduction processes due to the formation of radical anions of the oxadiazole units.

     

Aromatic poly(ester imide)s and poly(amide imide)s having 1,1′‐binaphthyl‐2,2′‐diyls in the main chain

Two new 1,1′‐binaphthyl‐2,2′‐diyl‐based dianhydrides, i. e., 2,2′‐bis(3,4‐dicarboxybenzamido)‐1,1′‐binaphthyl dianhydride (BNDADA) and 2,2′‐bis(3,4‐dicarboxybenzoyloxy)‐1,1′‐binaphthyl dianhydride (BNDEDA), were synthesized and polymerized with various aromatic diamines to afford polyimides through the traditional two‐step method. The polyimides with inherent viscosities ranging from 0.27 to 0.70 dl·g^–1 showed excellent solubilities in polar solvents such as DMAc, DMSO and NMP etc., except of the poly(ester imide) prepared from BNDEDA and benzidine. Poly(ester imide)s based on BNDEDA can also be readily dissolved in weakly polar solvents such as THF, CH₂Cl₂ and CHCl₃. The glass transition temperatures of these polyimides are in the range of 210–310°C; the 5% weight loss temperatures are in the range of 390–465°C in nitrogen and 384–447°C in air. These polymers form light yellow, tough films that were transparent above 365 nm. The effects of different flexible units attached in the 2‐ and 2′‐positions, i. e., amide, ester and ether, on the properties of the polyimides obtained are discussed.     

Novel Semi‐Fluorinated Poly(ether imide)s Derived From 4‐(p‐Aminophenoxy)‐3‐trifluoromethyl‐4′‐aminobiphenyl

An unsymmetrical diamine monomer 4‐(p‐aminophenoxy)‐3‐trifluoromethyl‐4′‐aminobiphenyl has been synthesized successfully. This monomer leads to the synthesis of different novel poly(ether imide)s when reacted with different dianhydrides like pyromellatic dianhydride (PMDA), benzophenone tetracarboxylic acid dianhydride (BTDA), 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane (6FDA), and oxy diphthalic anhydride (ODA). The poly(ether imide) prepared from this monomer on reaction with 6FDA is soluble in several organic solvents such as N‐methylpyrolidinone (NMP), dimethylformamide (DMF), N,N‐dimethylacetamide (DMAc), tetrahydrofuran (THF), and CHCl₃. The poly(ether imide)s prepared from BTDA and ODA are soluble in NMP, DMF, and DMAc but not in THF or CHCl₃, whereas the polymer prepared from PMDA is soluble only in NMP. The water uptake value for these poly(ether imide) films is very low (0.2–0.5%), and exhibited low dielectric constants (2.81 at 1 MHz). The polymers exhibited high thermal stability up to 532 °C in air for 5% weight loss, and high glass transition temperatures up to 288 °C. The polymer exhibited high tensile strength up to 135 MPa, modulus 3.2 GPa, and elongation at break up to 25%, depending on the exact polymer structure.

The structure of the poly(ether imide) synthesised from 4‐(p‐aminophenoxy)‐3‐trifluoromethyl‐4′‐aminobiphenyl and 2,2‐bis(3,4‐dicarboxyphenyl) hexafluoropropane. This polymer was soluble in many organic solvents.     

Preparation and properties of poly(amide-imide)s derived from trimellitic anhydride, α-amino acids,and aromatic diamines

Four dicarboxylic acids containing one preformed imide ring were prepared by condensation of trimellitic anhydride with α-amino acids such as glycine, DL -alanine, DL -valine, and DL -lcucinc. These diacids were subsequently directly polycondensated with various aromatic diamines using triphenyl phosphite (TPP) and pyridine as condensing agents in N-methyl-2-pyrrolidone (NMP) containing calcium chloride, producing various aliphatic-aromatic poly(amide-imide)s with pendant alkyl groups. The resultant polymers have inherent viscosities in the range of 0,58–2,15 dL/g and were amorphous, as revealed by wide-angle X-ray diffractograms. All polymers were readily soluble in a variety of solvents such as N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and NMP, and could be cast from their DMAc solutions into transparent, flexible, and tough films. All poly(amide-imide)s showed clear glass transition temperatures in the range of 181–313°C on the heating traces of differential scanning calorimetry (DSC). Almost all the poly(amide-imide)s exhibited no appreciable decomposition below 370°C, with 10% weight loss being recorded above 400°C in nitrogen and air. The polymers with larger side chain attached exhibited higher solubility, but lower glass transition temperature and initial decomposition temperature.     

Synthesis and properties of poly(ether imide)s derived from 4,4′-(1,5-naphthylenedioxy)diphthalic anhydride and various aromatic diamines

A naphthalene unit-containing bis(ether anhydride), 4,4′-(1,5-naphthylenedioxy)-diphthalic anhydride, was prepared in three steps starting from the nucleophilic nitro-displacement reaction of 1,5-dihydroxynaphthalene and 4-nitrophthalonitrile in N,N-dimethylformamide (DMF) solution in the presence of potassium carbonate. High-molarmass aromatic poly(ether imide)s were synthesized using a two-stage polymerization process from the bis(ether anhydride) and ten aromatic diamines. The intermediate poly(ether amic acid)s had inherent viscosities of 0,66–1,27 dL/g. The films of poly(ether imide)s derived from some diamines, such as p-phenylenediamine, benzidine, and bis[4-(4-aminophenoxy)phenyl] ether, crystallized and embrittled during the thermal imidization process. The other poly(ether imide)s were amorphous materials and could be fabricated into transparent, flexible, and tough films. These poly(ether imide) films had yield strengths of 111–125 MPa, tensile strengths of 96–150 MPa, elongations to break of 10–38%, and initial moduli of 1,6–2,4 GPa. All of these polymers were insoluble in organic solvents, except for that derived from 2,2-bis[(4-aminophenoxy)phenyl]propane. Their T_g's were recorded in the range of 226–265°C by DSC. Thermogravimetric analysis (TG) showed that all the polymers were stable up to 535°C in both air and nitrogen atmosphere.     

Thermally Cross‐Linkable Poly(p‐xylylene)s for Advanced Low‐Dielectric Applications

A novel series of poly(p‐xylylene) homopolymer and copolymers containing thermally cross‐linkable cyclohexenyl moiety are prepared via base‐catalyzed Gilch route to yield high‐molecular‐weight polymers. The resulting polymers are highly soluble in a wide range of organic solvents and could be solution cast into flexible and transparent films. The polymers are thermally stable up to 350 °C and the glass transition temperature (T_g) is in the range of 136 ? 250 °C. They undergo thermal cross‐linking via the cyclohexenyl moiety. The cross‐linked polymer exhibits a high T_g of 294 °C, a low coefficient of thermal expansion (CTE) of 45 ppm K^?1. A low dielectric constant of 2.5 and a very low dielectric loss tan δ of 0.0004 at 1 GHz are obtained, which are superior to conventional interconnect polymers.     

Synthesis and Characterization of New Cardo Polyamides and Polyimides bearing a 4‐Phenylcyclohexylidene Unit

A new cardo diamine monomer, 1,1‐bis[4‐(4‐aminophenoxy)phenyl]‐4‐phenylcyclohexane bearing a 4‐phenylcyclohexylidene unit, was prepared in three steps from 4‐phenylcyclohexanone. The monomer was reacted with various aromatic dicarboxylic acids and tetracarboxylic dianhydrides to produce novel polyamides and polyimides, respectively. The polyamides were prepared utilizing Yamazaki reaction conditions with inherent viscosities of 0.62–0.98 dL·g^–1. The polyimides were prepared by a two‐stage procedure that included a ring‐opening polyaddition to give poly(amic acid)s, followed by thermal or chemical cyclodehydration. By chemical cyclodehydration, the obtained polyimides had inherent viscosities of 0.61–0.93 dL·g^–1. Most of the polymers dissolved in N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide, N,N‐dimethylformamide, dimethyl sulfoxide, pyridine, and cyclohexanone. These polymers showed glass transition temperatures between 225–312°C and decomposition temperatures at 10% weight loss temperatures ranging from 470–500°C and 480–510°C in nitrogen and air atmosphere, respectively. These tough and flexible polymer films had a tensile strength of 81–124 MPa, an elongation at break of 8–21%, and tensile modulus of 2.0–2.8 GPa.     

Synthesis and characterization of new cardo polyamides and polyimides containing tert‐butylcyclohexylidene units

A new cardo diamine monomer, 1,1‐bis[4‐(4‐aminophenoxy)phenyl]‐4‐tert‐butylcyclohexane containing tert‐butylcyclohexylidene units was prepared in three steps from 4‐tert‐butylcyclohexanone. The monomer was reacted with various aromatic dicarboxylic acids and tetracarboxylic dianhydrides to produce polyamides and polyimides, respectively. All the polymers, characterized by X‐ray diffraction, are amorphous. These cardo polymers exhibit good solubility in a variety of solvents. Almost all polymers are soluble in N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridine, and even in tetrahydrofuran (THF) and cyclohexanone. The polymers show glass transition temperatures between 244–310°C and decomposition temperatures at 10% mass loss ranging from 486–526°C in nitrogen. The tough and flexible polymer films have tensile strength of 77–137 MPa, elongations at break of 5–14%, and tensile moduli of 2.0–2.6 GPa.     

Organosoluble optically transparent poly(ether imide)s based on a tert‐butylhydroquinone bis(ether anhydride)

A novel bis(ether anhydride) monomer, 1,4‐bis(3,4‐dicarboxyphenoxy)‐2‐tert‐butylbenzene dianhydride, was synthesized from the nitro displacement of 4‐nitrophthalodinitrile by the phenoxide ion of tert‐butylhydroquinone, followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and dehydration of the resulting bis(ether diacid). A series of colorless and organosoluble poly(ether imide)s (PEIs) bearing pendent tert‐butyl groups were prepared from the bis(ether anhydride) with various aromatic diamines via a conventional two‐stage process that included ring‐opening polyaddition to form the poly(amic acid)s followed by chemical or thermal cyclodehydration to the PEIs. The inherent viscosities of these PEIs are in the range of 0.70–1.44 dL/g. Most PEIs show excellent solubilities in amide polar solvents, m‐cresol and chlorohydrocarbons. The glass transition temperatures (T_g) of these PEIs were recorded between 217–278°C, and the decomposition temperatures at 10% weight loss are all above 460°C in air or nitrogen atmosphere. Solvent‐cast films have high tensile moduli and strengths. The PEIs obtained from long chain diamines exhibit high extension to break.     

Synthesis and Properties of New N‐Methylated Aliphatic‐Aromatic Polyamides Derived from N,N′‐Dimethylalkylenediamines and 4,4′‐Biphenyl‐dicarboxylic and 4,4″‐p‐Terphenyldicarboxylic Acids

Two new series of N‐methylated aliphatic‐aromatic polyamides were prepared by interfacial polycondensation of N,N ′‐dimethylalkylenediamines having 6–10 methylene units with 4,4′‐biphenyldicarbonyl and 4,4″‐p‐terphenyldicarbonyl chlorides. All of the N‐methylated polyamides were soluble in chlorinated hydrocarbon solvents, and the solubilities of the biphenyl‐based polyamides were higher than those of the terphenyl‐containing polymers. The biphenyl‐bearing polyamides with an even‐number of methylene units were crystalline and their odd‐numbered neighbors were amorphous, whereas all of the terphenyl‐containing polymers were crystalline. The melting temperatures of the terphenyl‐based polyamides (220–307°C) were higher than those of the biphenyl‐bearing polymers (180–207°C). Among these N‐methylated polyamides, the terphenyl‐containing polyamide having 7 methylene units showed enantiotropic liquid crystallinity.