Synthesis and characterization of hyperbranched polyimides with good organosolubility and thermal properties based on a new triamine and conventional dianhydrides

A triamine monomer, 1,3,5‐tris(4‐aminophenoxy)benzene (TAPOB), was synthesized from phloroglucinol and 4‐chloronitrobenzene, and it was successfully polymerized into soluble hyperbranched polyimides (HB PIs) with commercially available dianhydrides: 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4′‐oxydiphthalic anhydride (ODPA), and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA). Different monomer addition methods and different monomer molar ratios resulted in HB PIs with amino or anhydride end groups. From ¹H NMR spectra, the degrees of branching of the amino‐terminated polymers were estimated to be 0.65, 0.62, and 0.67 for 6FDA–TAPOB, ODPA–TAPOB, and BTDA–TAPOB, respectively. All polymers showed good thermal properties with 10% weight‐loss temperatures (T₁₀'s) above 505 °C and glass‐transition temperatures (T_g's) of 208–282 °C for various dianhydrides. The anhydride‐terminated HB PIs showed lower T₁₀ and T_g values than their amino‐terminated counterparts. The chemical conversion of the terminal amino or anhydride groups of the 6FDA‐based polyimides into an aromatic imido structure improved their thermal stability, decreased their T_g, and improved their solubility. The HB PIs had moderate molecular weights with broad distributions. The 6FDA‐based HB PIs exhibited good solubility even in common low‐boiling‐point solvents such as chloroform, tetrahydrofuran, and acetone. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3804–3814, 2002     

Synthesis of autophotosensitive hyperbranched polyimides based on 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride and 1,3,5‐tris(4‐aminophenoxy)benzene via end capping of the terminal anhydride groups by ortho‐alkyl aniline

Benzophenone‐containing, anhydride‐terminated hyperbranched poly(amic acid)s were end‐capped by ortho‐alkyl aniline in situ and then chemically imidized, yielding autophotosensitive hyperbranched polyimides. The polyimides were soluble in strong polar solvents, such as N‐methyl‐2‐pyrrolidone, N‐dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. Thermogravimetric analysis revealed their excellent thermal stability, with a 5 wt % thermal loss temperature in the range of 527–548 °C and a10 wt % thermal loss temperature in the range of 562–583 °C. The strong absorption of the polyimide films in ultraviolet–visible spectra at 365 nm indicated that the hyperbranched polyimides were patternable. Highly resolved images with a line width of 6 μm were developed by ultraviolet exposure of the polymer films. A well‐defined image with lines as thin as 3 μm was also patterned, but the lines were rounded at the edges. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2026–2035, 2003     

Synthesis and characterization of soluble polyimides derived from 2′,5′‐bis(3,4‐dicarboxyphenoxy)‐p‐terphenyl dianhydride

A novel bis(ether anhydride) monomer, 2′,5′‐bis(3,4‐dicarboxyphenoxy)‐p‐terphenyl dianhydride, was synthesized from the nitro displacement of 4‐nitrophthalonitrile by the phenoxide ion of 2′,5′‐dihydroxy‐p‐terphenyl, followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and cyclodehydration of the resulting bis(ether diacid). A series of new poly(ether imide)s bearing laterally attached p‐terphenyl 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 thermal or chemical imidization to the poly(ether imide)s. The inherent viscosities of the poly(amic acid) precursors were in the range of 0.62–1.26 dL/g. Most of the poly(ether imide)s obtained from both routes were soluble in polar organic solvents, such as N,N‐dimethylacetamide. All the poly(ether imide)s could afford transparent, flexible, and strong films with high tensile strengths. The glass‐transition temperatures of these poly(ether imide)s were recorded as between 214 and 276 °C by DSC. The softening temperatures of all the poly(ether imide) films stayed in the 207–265 °C range according to thermomechanical analysis. For all the polymers significant decomposition did not occur below 500 °C in nitrogen or air atmosphere. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1008–1017, 2004     

Synthesis of alkaline‐developable,photosensitive hyperbranched polyimides through the reaction of carboxylic acid dianhydrides and trisamines

Hyperbranched polyimides (HBPI)s with high glass‐transition temperatures and excellent thermal stability were synthesized through the reaction of commercially available carboxylic acid dianhydrides with tris[4‐(4‐aminophenoxy)phenyl]ethane (TAPE). In particular, hyperbranched polyimide HBPI(TAPE‐DSDA), prepared through the reaction of TAPE with 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride (DSDA), showed higher thermal stability and good solubility. Furthermore, alkaline‐developable, photosensitive HBPI(TAPE‐DSDA)‐MA‐CA was prepared through the reaction of HBPI(TAPE‐DSDA) with glycidyl methacrylate with tetrabutylammonium bromide as a catalyst in N‐methyl‐2‐pyrrolidinone (NMP) followed by the addition reaction of cis‐1,2,3,6‐tetrahydrophthalic anhydride with triphenylphosphine as a catalyst in NMP. The glass‐transition temperatures of HBPI(TAPE‐DSDA)‐MA‐CA were greater than 300 °C. A resist composed of 74 wt % HBPI(TAPE‐DSDA)‐MA‐CA, 22.2 wt % trimethylpropane triacrylate, and 3.8 wt % Irgacure 907 as a photoinitiator achieved a resolution of a 55‐μm line pattern and a 275‐μm space pattern by UV irradiation (1000 mJ/cm²). © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3697–3707, 2004     

Synthesis of hyperbranched poly(ether nitrile)s by one‐step polycondensation of an AB2 monomer

Hyperbranched poly(ether nitrile)s were prepared from a novel AB₂ type monomer, 2‐chloro‐4‐(3,5‐dihydroxyphenoxy)benzonitrile, via nucleophilic aromatic substitution. Soluble and low‐viscous hyperbranched polymers with molecular weights upto 233,600 (M_w) were isolated. According to the ¹H NMR and GPC data, the unique polymerization behavior was observed, which implies that the weight average molecular weight increased after the number average molecular weight reached plateau region. Model compounds were prepared to characterize the branching structure. Spectroscopic measurements of the model compounds and the resulting polymers, such as ¹H, DEPT ¹³C NMR, and MS, strongly suggest that the ether exchange reaction and cyclization are involved in the propagation reaction. The side reactions would affect the unique polymerization behavior. The resulting polymers showed a good solubility in organic solvents similar to other hyperbranched aromatic polymers. The hydroxy‐terminated polymer was even soluble in basic water. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5835–5844, 2009     

Hyperbranched poly(ether–urea)s using AB2‐type blocked isocyanate monomer and azide monomer: Synthesis,characterization, reactive end functionalization,and copolymerization with AB monomer

3,5‐bis(4‐aminophenoxy)phenyl phenylcarbamate—a novel AB₂‐type blocked isocyanate monomer and 3,5‐bis{ethyleneoxy(4‐aminophenoxy)}phenyl carbonyl azide—a novel AB₂‐type azide monomer were synthesized in high yield. Step‐growth polymerization of these monomers were found to give a first example of hyperbranched poly (aryl‐ether‐urea) and poly(aryl‐alkyl‐ether‐urea). Molecular weights (M_w) of the polymer were found to vary from 1,858 to 52,432 depending upon the monomer and experimental conditions used. The polydispersity indexes were relatively narrow due to the controlled regeneration of isocyanate functional groups for the polymerization reaction. The degree of branching (DB) was determined using ¹H‐NMR spectroscopy and the values ranged from 87 to 54%. All the polymers underwent two‐stage decomposition and were stable up to 300 °C. Functionalized end‐capping of poly(aryl‐ether‐urea) using phenylchloroformate and di‐t‐butyl dicarbonate (Boc)₂O changed the thermal properties and solubility of the polymers. Copolymerization of AB₂‐type blocked isocyante monomer with functionally similar AB monomer were also carried out. The molecular weights of copolymers were found to be in the order of 6 × 10⁵ with narrow dispersity. It was found that the T_g's of poly(aryl‐alkyl‐ether‐urea)s were significantly less (46–49 °C) compared to poly(aryl‐ether‐urea)s. Moreover the former showed melting transition at 154 °C, which was not observed in the latter case. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2959–2977, 2007     

Self‐controlled synthesis of hyperbranched poly(ether‐ketone)s from A2 + B3 approach in poly(phosphoric acid)

Self‐controlled synthesis of hyperbranched poly(ether‐ketone)s (HPEKs) were prepared from “A₂ + B₃” approach by using different monomer solubility in reaction medium. 1,3,5‐Triphenoxybenzene as a hydrophobic B₃ monomer was reacted with commercially available terephthalic acid or 4,4′‐oxybis(benzoic acid) as a hydrophilic A₂ monomer in a hydrophilic reaction medium, polyphosphoric acid (PPA)/phosphorous pentoxide (P₂O₅). The resultant HPEKs were soluble in various common organic solvents and had the weight‐average molecular weight in the range of 3900–13,400 g/mol. The results implied that HPEKs were branched structures instead of crosslinked polymers. The molecular sizes and shapes of HPEKs were further assured by morphological investigation with scanning electron microscopy (SEM) and atomic force microscopy (AFM). Hence, the applied polymerization condition was indeed strong enough to efficiently facilitate polycondensation via “direct” Friedel‐Crafts reaction without gelation. It could be concluded that the polymer forming reaction was kinetically controlled by automatic and slow feeding of the hydrophobic B₃ monomer into the hydrophilic reaction mixture containing hydrophilic comonomer. As a result, hyperbranched structures were formed instead of crosslinked polymers even at full conversion (equifunctional monomer feed ratio). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3326–3336, 2009     

Poly(ether imide)s derived from phthalazinone‐containing dianhydrides

An unsymmetrical and noncoplanar heterocyclic dianhydride was synthesized from a bisphenol‐like phthalazinone, 4‐(4‐hydroxylphenyl)‐2,3‐phthalazin‐1‐one, and a series of novel poly(ether imide)s based on it, with intrinsic viscosities of 0.67–1.42 dL/g, were obtained by one‐step solution polymerization in m‐cresol at 200 °C for 20 h. The polymers were readily soluble in N‐methyl‐2‐pyrrolidinone and m‐cresol. The poly(ether imide)s derived from 4,4′‐oxydianiline and 4,4′‐methylenedianiline were also very soluble in chloroform, 1,1′,2,2′‐tetrachloroethane, and N,N‐dimethylacetamide. The glass‐transition temperatures were 289–326 °C, as determined by differential scanning calorimetry. All the degradation temperatures for 5% weight loss occurred above 482 °C in nitrogen. The tensile strength of thin films of some of the polymers varied from 103.1 to 121.4 MPa. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6089–6097, 2004     

Hydroxyl‐terminated hyperbranched aromatic poly(ether‐ester)s: Synthesis,characterization, end‐group modification,and optical properties

Novel AB₂‐type monomers such as 3,5‐bis(4‐methylolphenoxy)benzoic acid ( monomer 1 ), methyl 3,5‐bis(4‐methylolphenoxy) benzoate ( monomer 2 ), and 3,5‐bis(4‐methylolphenoxy)benzoyl chloride ( monomer 3 ) were synthesized. Solution polymerization and melt self‐polycondensation of these monomers yielded hydroxyl‐terminated hyperbranched aromatic poly(ether‐ester)s. The structure of these polymers was established using FTIR and ¹H NMR spectroscopy. The molecular weights (M_w) of the polymers were found to vary from 2.0 × 10³ to 1.49 × 10⁴ depending on the polymerization techniques and the experimental conditions used. Suitable model compounds that mimic exactly the dendritic, linear, and terminal units present in the hyperbranched polymer were synthesized for the calculation of degree of branching (DB) and the values ranged from 52 to 93%. The thermal stability of the polymers was evaluated by thermogravimetric analysis, which showed no virtual weight loss up to 200 °C. The inherent viscosities of the polymers in DMF ranged from 0.010 to 0.120 dL/g. End‐group modification of the hyperbranched polymer was carried out with phenyl isocyanate, 4‐(decyloxy)benzoic acid and methyl red dye. The end‐capping groups were found to change the thermal properties of the polymers such as T_g. The optical properties of hyperbranched polymer and the dye‐capped hyperbranched polymer were investigated using ultraviolet‐absorption and fluorescence spectroscopy. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5414–5430, 2008     

Hydroxyl‐ and amine‐terminated hyperbranched polyurethanes using AB2‐type azide monomers: Synthesis,characterization, fluorescence,and charge‐transfer complexation studies

Novel AB₂‐type azide monomers such as 3,5‐bis(4‐methylolphenoxy)carbonyl azide (monomer 1) , 3,5‐bis(methylol)phenyl carbonyl azide (monomer 2) , 4‐(methylol phenoxy) isopthaloyl azide (monomer 3) , and 5‐(methylol) isopthaloyl azide (monomer 4) were synthesized. Melt and solution polymerization of these monomers yielded hydroxyl‐ and amine‐terminated hyperbranched polyurethanes with and without flexible ether groups. The structures of theses polymers were established using FT‐IR and NMR spectroscopy. The molecular weights (M_w) of the polymers were found to vary from 3.2 × 10³ to 5.5 × 10⁴ g/mol depending on the experimental conditions used. The thermal properties of the polymers were evaluated using TGA and DSC: the polymer obtained from monomer ( 1 ) exhibited lowest T_g and highest thermal stability and the polymer obtained from monomer ( 2 ) registered the highest T_g and lowest thermal stability. All the polymers displayed fluorescence maxima in the 425–525 nm range with relatively narrow peak widths indicating that they had pure and intense fluorescence. Also, the polymers formed charge transfer (CT) complexes with electron acceptor molecules such as 7,7,8,8‐tetracyano‐quino‐dimethane (TCNQ) and 1,1,2,2‐tetracyanoethane (TCNE) as evidenced by UV‐visible spectra. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3337–3351, 2009     

Synthesis and properties of organosoluble poly(amide imide imide)s based on tetraimide dicarboxylic acid condensed from 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 4,4′‐oxydianiline,and trimellitic anhydride and various aromatic diamines

A novel tetraimide dicarboxylic acid was synthesized with the ring‐opening addition of 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 4,4′‐oxydianiline, and trimellitic anhydride in a 1/2/2 molar ratio in N‐methyl‐2‐pyrrolidone followed by azeotropic condensation to tetraimide dicarboxylic acid. A series of poly(amide imide imide)s (PAIIs) with inherent viscosities of 0.8–1.1 dL/g were prepared from tetraimide dicarboxylic acid with various aromatic diamines by direct polycondensation. Most of the PAIIs were readily soluble in a variety of amide polar solvents and even in less polar m‐cresol and pyridine. Solvent‐cast films had tensile strengths ranging from 99 to 106 MPa, elongations at break ranging from 8 to 13%, and initial moduli ranging from 2.0 to 2.3 GPa. The glass‐transition temperatures of these PAIIs were recorded at 244–276 °C. They had 10% weight losses at temperatures above 520 °C in air or nitrogen atmospheres. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1092–1102, 2002     

Synthesis and properties of long‐chain branched poly(ether sulfone)s by self‐polycondensation of AB2 type macromonomers

Long‐chain branched poly(ether sulfone)s (PESs) were synthesized via self‐polycondensation of AB₂ macromonomers. The linear PES oligomers synthesized by self‐polycondensation of 4‐chloro‐4′‐(4‐hydroxyphenyloxy)diphenyl sulfone were terminated with 4‐(3,5‐methoxyphenoxy)‐4′‐fluorodiphenyl sulfone to form AB₂ macromonomer precursors. After conversion from methoxy to hydroxy groups, the AB₂ macromonomers were self‐polycondensed to form long‐chain branched PESs. NMR measurements support the formation of the target macromonomers ( = 2930–67,800 (g mol^?1); M_n = number average molecular weight) and long‐chain branched PESs. Gel permeation chromatography with multiangle light scattering measurements indicated the formation of high‐molecular‐weight (M_w) polymers over 10⁴. The root‐mean‐square radius of gyration (R_g) suggests that the shape of the long‐chain branched PES synthesized from small AB₂ macromonomers in solution is similar to that of hyperbranched polymers. Increasing resulted in larger R_g, suggesting a transition from hyperbranched to a linear‐like architecture in the resulting long‐chain branched PESs. Rheological measurements suggested the presence of strongly entangled chains in the long‐chain branched PES. Higher tensile modulus and smaller elongation at the break were observed in the tensile tests of the long‐chain branched PESs. It is assumed that the enhanced molecular entanglement points may act as physical crosslinks at room temperature. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1825–1831     

Synthesis and characterization of phthalazinone containing poly(arylene ether)s via a novel N–C coupling reaction

High‐molecular‐weight poly(phthalazinone)s with very high glass‐transition temperatures (T_g's) were synthesized via a novel N–C coupling reaction. New bisphthalazinone monomers ( 7a–e ) were synthesized from 2‐(4‐chlorobenzoyl) phthalic acid in two steps. Poly(phthalazinone)s, having inherent viscosities in the range of 0.34–0.91 dL/g, were prepared by the reaction of the bis(phthalazinone) monomers with an activated aryl halide in a dipolar aprotic solvent in the presence of potassium carbonate. The poly(phthalazinone)s exhibited T_g's greater than 230 °C. polymer 8b synthesized from diphenyl biphenol and bis(4‐flurophenyl) sulfone demonstrated the highest T_g of 297 °C. Thermal stabilities of the poly(phthalazinone)s were determined by thermogravimetric analysis. All the poly(phthalazinone)s showed a similar pattern of decomposition with no weight loss below 450 °C in nitrogen. The temperatures of 5% weight loss were observed to be about 500 °C. The poly(phthalazinone)s containing 4,4′‐isopropylidenediphenol and 4,4′‐(hexafluoroisopropylidene) diphenol and diphenyl ether linkage were soluble in chlorinated solvents such as chloroform. Other poly‐(phthalazinone)s were soluble in dipolar aprotic solvents such as N,N′‐dimethylacetamide. The soluble poly(phthalazinone)s can be cast as flexible films from solution. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2481–2490, 2003     

Synthesis and characterization of the B3-monomer and hyperbranched poly(aryl ether ketone)s

Hyperbranched poly(aryl ether ketone)s were prepared by polymerization of hydroquinone (A₂) and 1,3,5-tris[4-(4-fluorobenzoyl)phenoxy]benzene (B₃). The gelation of hyperbranched poly(aryl ether ketone)s was effectively avoided. Hydroxyl-term inated (HPAEK-OH) and fluoro-terminated (HPAEK-F) hyperbranched poly(aryl ether ketone)s were prepared by using different A₂/B₃ mass ratio. The structure of the B₃ monomer was confirmed by MS, ¹H NMR/IR. The glass transition temperatures of the HPAEK-F and HPAEK-OH are 114°C and 162°C respectively. Thermal stability of HPAEK-F is higher than HPAEK-OH. __________ Translated from Acta Scientianum Naturalium Universitatis Jilinensis, 2005, 5 (in Chinese)     

Synthesis and properties of soluble and light‐colored poly(amide‐imide‐imide)s on the basis of tetraimide‐dicarboxylic acid condensed from 4,4′‐oxydiphthalic anhydride, 2,2‐bis[4‐(4‐aminophenoxy)phenyl]propane,and m‐aminobenzoic acid,and various aromatic diamines

A new type of tetraimide‐dicarboxylic acid ( I ) was synthesized starting from the ring‐opening addition of m‐aminobenzoic acid, 4,4′‐oxydiphthalic anhydride, and 2,2‐bis[4‐(4‐aminophenoxy)phenyl]propane at a 2:2:1 molar ratio in N‐methyl‐2‐pyrrolidone (NMP), followed by cyclodehydration to the diacid I . A series of soluble and light‐colored poly(amide‐imide‐imide)s ( III _a–j) was prepared by triphenyl phosphite‐activated polycondensation from I with various aromatic diamines ( II _a–j). All films cast from N,N‐dimethylacetamide (DMAc) had cutoff wavelengths shorter than 390 nm (374–390 nm) and b* values between 25.26 and 43.61; these polymers were much lighter in color than the alternating trimellitimide series. All of the polymers were readily soluble in a variety of organic solvents such as NMP, DMAc, N,N‐dimethylformamide, dimethyl sulfoxide, and even in less polar m‐cresol and pyridine. Polymers III _a–j afforded tough, transparent, and flexible films that had tensile strengths ranging from 96 to 118 MPa, elongations at break from 9 to 11%, and initial moduli from 2.0 to 2.5 GPa. The glass‐transition temperatures of the polymers were recorded at 240–268 °C. They had 10% weight loss at a temperature above 540 °C and left more than 55% residue even at 800 °C in nitrogen. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 707–718, 2002; DOI 10.1002/pola.10153     

Novel heterocyclic poly(arylene ether ketone)s: Synthesis and polymerization of 4‐(4′‐hydroxyaryl)(2H)phthalazin‐1‐ones with methyl groups

Based on green chemistry, a simple and efficient direct synthesis of 4‐(4′‐hydroxyaryl)(2H)phthalazin‐1‐ones ( 2a–2f ) was developed in a two‐step reaction, in which the Friedel–Crafts acylation reaction of six phenols with phthalic anhydride was initially carried out and then followed by cyclization with hydrazine hydrate in good to excellent yields with high regioselectivity. A number of novel heterocyclic poly(arylene ether ketone)s were prepared conveniently from several unsymmetrical, twist, and noncoplanar phthalazinone‐containing monomers ( 2a–2f ) and an activated difluoro monomer via a N? C coupling reaction. It was very interesting that the obtained monomers and polymers exhibited diverse properties with the variation of the number and location of the substituted methyl groups. All these polymers had a high molecular weight with M_n and η_inh in the range of 44,960–169,000 Da and 0.38–0.79 dL/g, respectively. Actually, the obtained polymers displayed excellent thermal properties with T_g's ranging from 222 to 248 °C and 5% weight loss temperatures in nitrogen higher than 430 °C. Moreover, these polymers were readily soluble in common organic solvents, such as N‐methyl‐2‐pyrrolidone, chloroform, pyridine, and m‐cresol, and could be cast into flexible and colorless or nearly colorless films by spin‐coating or casting processes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1525–1535, 2007     

Synthesis,characterization, and investigation of structure‐thermal cycloimidization relationship of novel poly(amide amic acid)s to poly(amide imide)s by thermogravimetric analysis

Novel diamic acids (DAAs) and poly(amide amic acid)s (PAAs) were prepared and their thermal cycloimidization to the corresponding imide form was investigated by thermogravimetric analysis under isothermal conditions at four different temperatures, that is, at 175, 200, 225, and 260 °C for 75 min. A general equation, 18NW/R_MW, where, the numerical 18 corresponds to the molecular weight of water, N is the number of water molecules, which would be eliminated per repeat unit of the PAA upon cycloimidization, W is the weight of PAA taken for TGA, and R is the molecular weight of the repeat unit of PAA, has been derived for the calculation of theoretical amount of weight loss of PAA upon complete cycloimidization. The degree of cycloimidization (DCI%) of PAAs to poly(amide imide)s (PAI) has been calculated from their isothermal TGA curves. The variation in DCI on temperature, time, and the structures of diamine and acid chloride, especially, with respect to meta‐ and para‐linkages and the presence of electron withdrawing groups has been discussed. Cycloimidization occurs at faster rate in the initial stages of about 20 min, curing and then proceeds in a gradual manner and reaches almost a plateau within an hour. The DCI was more at higher temperatures, and the final values were 22?60% at 175 °C, 34?78% at 200 °C, 50?96% at 225 °C, and 85?99% at 260 °C after 75 min of heating, depending on the nature of diamine and acid chloride in the PAA. The DCI of PAAs with meta‐linkages in either of diamine or diacid chloride was somewhat lower than those having para‐linkages. The DCI of PAAs containing electron withdrawing group like sulfone in the diamine is somewhat higher compared with those of others. The final DCI (%) values obtained from FT‐IR spectra and isothermal TGA curves were very close to each other. Further, the thermal and thermooxidative stabilities of the PAIs were discussed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2937–2947, 2007     

Synthesis of hyperbranched polyacetals via an + b2‐type polyaddition (n = 3, 8, 18, and 21): Candidate resists for extreme ultraviolet lithography

Polyaddition (A_n + B₂) reactions of 1,1,1‐tris(4‐hydoxyphenyl) ethane (THPE; A₃‐type monomer), calix[4]resorcinarene (CRA[4]; A₈‐type monomer), α‐cyclodextrin (α‐CD; A₁₈‐type monomer), and β‐cyclodextrin (β‐CD; A₂₁‐type monomer) with 1,4‐bis(4‐vinyloxy)cyclohexane (BVOC; B₂‐type monomer) afforded corresponding soluble hyperbranched polyacetals. The physical properties, including solubility, thermal stability, and film‐forming ability, the ultraviolet‐induced degradation reactivity, and the solubility‐switch in an extreme ultraviolet (EUV) exposure tool indicated that poly(THPE‐co‐BVOC) and poly(CRA[4]‐co‐BVOC) are candidate next‐generation photo‐resists. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2343–2350     

Synthesis and characterization of new highly organosoluble poly(etherimide)s derived from 1,1‐bis{4‐[4‐(3,4‐dicarboxyphenoxy)phenyl]‐4‐phenylcyclohexane} dianhydride

A new bulky pendent bis(ether anhydride), 1,1‐bis[4‐(4‐dicarboxyphenoxy)phenyl]‐4‐phenylcyclohexane dianhydride, was prepared in three steps, starting from the nitrodisplacement of 1,1‐bis(4‐hydroxyphenyl)‐4‐phenylcyclohexane with 4‐nitrophthalonitrile to form bis(ether dinitrile), followed by alkaline hydrolysis of the bis(ether dinitrile) and subsequent dehydration of the resulting bis(ether diacid). A series of new poly(ether imide)s were prepared from the bis(ether anhydride) with various diamines by a conventional two‐stage synthesis including polyaddition and subsequent chemical cyclodehydration. The resulting poly(ether imide)s had inherent viscosities of 0.50–0.73 dL g^?1. The gel permeation chromatography measurements revealed that the polymers had number‐average and weight‐average molecular weights of up to 57,000 and 130,000, respectively. All the polymers showed typical amorphous diffraction patterns. All of the poly(ether imide)s showed excellent solubility in comparison with the other polyimides derived from adamantane, norbornane, cyclododecane, and methanohexahydroindane and were readily dissolved in various solvents such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethylacetamide (DMAc), N,N‐dimethylformamide, pyridine, cyclohexanone, tetrahydrofuran, and even chloroform. These polymers had glass‐transition temperatures of 226–255 °C. Most of the polymers could be dissolved in chloroform in as high as a 30 wt % concentration. Thermogravimetric analysis showed that all polymers were stable up to 450 °C, with 10% weight losses recorded from 458 to 497 °C in nitrogen. These transparent, tough, and flexible polymer films could be obtained by solution casting from DMAc solutions. These polymer films had tensile strengths of 79–103 MPa and tensile moduli of 1.5–2.1 GPa. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2066–2074, 2002