Synthesis and Characterization of a Highly Soluble Aromatic Polyimide from 4,4′‐Methylenebis(2‐tert‐butylaniline)

4,4′‐Methylenebis(2‐tert‐butylaniline) was synthesized and reacted with pyromellitic dianhydride to produce a polyimide that showed excellent solubility in conventional organic solvents. Solutions of this polyimide could be cast into transparent, flexible and tough films. The number‐average molecular weight, as determined by means of gel permeation chromatography, was 8.9×10⁴ g/mol and the polydispersity index was 1.97. The glass transition temperature was found to be 217°C. The polyimide did not show appreciable decomposition up to 500°C under a nitrogen atmosphere.     

Photo‐regulated phase transition of poly(ethylene glycol) derivative containing azobenzene group

A photo‐responsive and thermo‐responsive poly(ethylene glycol) derivative containing azobenzene group was synthesized. Its photoisomerization kinetics was investigated by the UV–vis spectra, and the pseudo‐first‐order rate constants (k_t and k_c) were determined to be 1.5 × 10^?2 and 9.3 × 10^?2 s^?1, respectively. It is found that the phase transition behavior can be tuned theoretically through photoirradiation between 26.6°C and 36.7°C. Finally, it is worthy to note that the changes of the lower critical solution temperature occur repeatedly upon successive irradiation of UV and visible light. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis,characterization, photo‐induced alignment,and surface orientation of poly(9,9‐dioctylfluorene‐alt‐azobenzene)s

Three types of bi‐functionalized copolymers ( P1FAz , P2FAz , and P3FAz ) with different numbers of fluorene units and an azobenzene unit were synthesized and characterized using UV–vis and polarized absorption spectroanalysis. The trans‐cis photoisomerization was conformed under 400 nm light irradiation for all copolymers in chloroform. However, in the film state, only the trans‐cis photoisomerization occurred by mono‐fluorene attached copolymer poly[(9,9‐di‐n‐octylfluorenyl‐2,7‐diyl)‐alt‐4,4′‐azobenzene)] ( P1FAz ). Photo‐induced alignment was achieved using the P1FAz film after irradiation with linear polarized 400 nm light and subsequent annealing at 60 °C. Surface orientation of a spin‐coating film of poly(9,9‐didodecylfluorene) ( F12 ) was achieved using the photo‐induced alignment layer of the P1FAz film after annealing at 90 °C. The photo‐induced alignment layer of P1FAz has potential application to the surface orientation technique for appropriate polymers, which will be useful for the fabrication of optoelectronics devices. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and characterization of photo‐crosslinkable poly(amic acid ester)s with 2‐hydroxy‐4‐oxo‐hept‐5‐enyl side chain

Photosensitive poly(amic acid ester)s (PAEs) with 2‐hydroxy‐4‐oxo‐hept‐5‐enyl side group were simply synthesized from a non‐photosensitive polyamic acid (PAA), which was prepared from cyclobutane‐1,2,3,4‐tetracarboxylic dianhydride (CBDA) and 4,4′‐diaminodiphenyl ether (DDE) in N‐methyl‐2‐pyrrolidinone (NMP). 1‐oxiranyl‐pent‐3‐en‐2‐one was added to the poly(amic acid) solution to give the photosensitive PAEs by a ring opening esterification of the poly(amic acid). The esterification reaction was conducted with changing a reaction time and amounts of 1‐oxiranyl‐pent‐3‐en‐2‐one. The degree of esterification (DOE) increased with increasing esterification reaction time and amounts of 1‐oxiranyl‐pent‐3‐en‐2‐one. A photo‐lithography evaluation for the PAE‐D4 with the highest DOE was conducted in the presence of 1‐[4‐(phenylthio)phenyl]‐2‐(O‐benzoyloxime)‐1,2‐octanedione (PPBO) as a photoinitiator at a wavelength of 365 nm using a high‐pressure mercury lamp. The normalized film thicknesses for PAE‐D3 were measured with various post‐exposure baking (PEB) temperatures, which showed that the optimum PEB temperature was 120°C. The resolution of the resulting polyimide film cured at 250°C for 60 min was 25 µm. The initial decomposition temperature of the polyimide film was around 354°C and there was no weight loss at the temperature of 250–350°C. Copyright © 2009 John Wiley & Sons, Ltd.     

Three‐component negative‐type photosensitive polyimide precursor based on poly(amic acid), a crosslinker,and a photoacid generator

A new negative‐working and alkaline‐developable photosensitive polyimide precursor based on poly(amic acid) (PAA), 4,4′‐methylenebis[2,6‐bis(hydroxymethyl)]phenol (MBHP) as a crosslinker, and a photoacid generator (5‐propylsulfonyloxyimino‐5H‐thiophen‐2‐ylidene)‐2‐(methylphenyl)acetonitrile (PTMA) has been developed. PAA was prepared by ring‐opening polymerization of pyromellitic dianhydride with 4,4′‐oxydianiline. The photosensitive polyimide precursor containing PAA (65 wt %), MBHP (25 wt %), and PTMA (10 wt %) showed a clear negative image featuring 10 μm line and space patterns when it was exposed to 436 nm light at 100 mJ·cm^?2, post‐exposure baked at 130 °C for 3 min, followed by developing with a 2.38 wt % aqueous tetramethylammonium hydroxide solution at 25 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 593–599, 2005     

Microwave‐enhanced rapid synthesis of organosoluble polyamides based on 5‐(3‐acetoxynaphthoylamino)‐isophthalic acid

A series of photoactive polyamides (PAs) containing acetoxynaphthalamide side chain with inherent viscosities of 0.27–0.56 dl g^?1 were prepared by the direct polycondensation reaction of the 5‐(3‐acetoxynaphthoylamino)isophthalic acid with various commercially available diamines by means of triphenyl phosphite (TPP) and pyridine (Py) in the presence of calcium chloride and N‐methyl‐2‐pyrrolidone (NMP) under microwave irradiation and conventional heating conditions. Most of the resulting PAs are soluble in strong polar solvents such as N,N‐dimethylformamide (DMF), N,N‐dimethylacetamide, and NMP. Thermo‐gravimetric analysis (TGA) showed that polymers are thermally stable, 10% weight loss temperatures in excess of 320 and 378°C, and char yields at 600°C in nitrogen higher than 60%. These macromolecules exhibited maximum UV‐Vis absorption at 265 and 300 nm in a DMF solution. Their photoluminescence in the DMF solution demonstrated fluorescence emission maxima around 361 and 427 nm for all of the PAs. Copyright © 2008 John Wiley & Sons, Ltd.     

Homologous SNV Reaction: Synthesis of l‐Methyl‐4‐[4′‐phenylsulfonyl‐1′,3′‐butadienyl]pyridinium Iodide and Its Reactivity with Thiol Groups Giving Rise to the Chromophoric Thioether

Thioether 4‐[(1′E,3′E)‐4′‐phenylsulfanyl‐1,3′‐butadienyl]pyridine 8 and sulfone 4‐(4′‐phenylsulfonyl‐1′,3′‐butadienyl)pyridine 14 were prepared by reaction of the carbanions derived from allylic thioether or allylic sulfone with isonicotinaldehyde. The reaction with the sulfonyl carbanion occurred at the α position and on heating the alcolate gave the dienic sulfone 14 . The corresponding pyridinium iodide 10 and 15 were prepared by reaction with methyl iodide, respectively, on pyridine derivates 8 and 14 . The dienic pyridinium thioether 10 showed a long wavelength absorption band centered at 420 nm. The reaction of dienic pyridinium sulfone 15 with thiophenol gave the dienic pyridinium thioether 10 by a nucleophilic vinylic substitution. The reaction of sulfone 15 with glutathione was of second order and the rate constant was 8.5 M^?1s^?1 at 30°C and pH 7, about 500 times smaller than the rate constant observed with (E)‐1‐methyl‐4‐(2‐methylsulfonyl‐1‐ethenyl)pyridinium iodide 1 . The dienic pyridinium thioether 10 was a negative solvatochrome.     

Synthesis and characterization of novel fluorinated polyimides derived from 4,4′‐[2,2,2‐trifluoro‐1‐(3‐trifluoromethylphenyl)ethylidene]diphthalic anhydride and aromatic diamines

A novel fluorinated aromatic dianhydride, 4,4′‐[2,2,2‐trifluoro‐1‐(3‐trifluoromethyl‐phenyl)ethylidene]diphthalic anhydride (TFDA) was synthesized by coupling of 3′‐trifluoromethyl‐2,2,2‐trifluoroacetophenone with o‐xylene under the catalysis of trifluoromethanesulfonic acid, followed by oxidation of KMnO₄ and dehydration. A series of fluorinated aromatic polyimides derived from the novel fluorinated aromatic dianhydride TFDA with various aromatic diamines, such as p‐phenylenediamine (p‐PDA), 4,4′‐oxydianiline (ODA), 1,4‐bis(4‐aminophenoxy)benzene (p‐APB), 1,3‐bis(4‐amino‐phenoxy)benzene (m‐APB), 4‐(4‐aminophenoxy)‐3‐trifluoromethylphenylamine (3FODA) and 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzene (6FAPB), were prepared by polycondensation procedure. All the fluorinated polyimides were soluble in many polar organic solvents such as NMP, DMAc, DMF, and m‐cresol, as well as some of low boiling point organic solvents such as CHCl₃, THF, and acetone. Homogeneous and stable polyimide solutions with solid content as high as 35–40 wt % could be achieved, which were prepared by strong and flexible polyimide films or coatings. The polymer films have good thermal stability with the glass transition temperature of 232–322 °C, the temperature at 5% weight loss of 500–530 °C in nitrogen, and have outstanding mechanical properties with the tensile strengths of 80.5–133.2 MPa as well as elongations at breakage of 7.1–12.6%. It was also found that the polyimide films derived from TFDA and fluorinated aromatic diamines possess low dielectric constants of 2.75–3.02, a low dissipation factor in the range of 1.27–4.50 × 10^?3, and low moisture absorptions <1.3%. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4143–4152, 2004     

Preparation and physical properties of poly(4,4′‐diamino‐3′‐carbamoylbenzanilide terephthalamide) and poly(4,4′‐diamino‐3′‐carbamoylbenzanilide isophthalamide) films

To prepare thermally stable and high‐performance polymeric films, new solvent‐soluble aromatic polyamides with a carbamoyl pendant group, namely poly(4,4′‐diamino‐3′‐carbamoylbenzanilide terephthalamide) (p‐PDCBTA) and poly(4,4′‐diamino‐3′‐carbamoylbenzanilide isophthalamide) (m‐PDCBTA), were synthesized. The polymers were cyclized at around 200 to 350 °C to form quinazolone and benzoxazinone units along the polymer backbone. The decomposition onset temperatures of the cyclized m‐ and p‐PDCBTAs were 457 and 524 °C, respectively, lower than that of poly(p‐phenylene terephthalamide) (566 °C). For the p‐PDCBTA film drawn by 40% and heat‐treated, the tensile strength and Young's modulus were 421 MPa and 16.4 GPa, respectively. The film cyclized at 350 °C showed a storage modulus (E′) of 1 × 10¹¹ dyne/cm² (10 GPa) over the temperature range of room temperature to 400 °C. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 775–780, 2000     

Design of photoresists with reduced environmental impact. II. Water‐soluble resists based on photocrosslinking of poly(2‐isopropenyl‐2‐oxazoline)

The performance of water‐ and solvent‐cast, two‐component photoresist films containing poly(2‐isopropenyl‐2‐oxazoline) or poly(2‐isopropenyl‐2‐oxazoline‐co‐styrene) with a photoacid generator has been investigated. These materials afford negative‐tone images after deep‐UV exposure and development in a suitable medium (water or toluene). Resist solutions prepared from polymers containing at least 80 mol % 2‐isopropenyl‐2‐oxazoline may be cast from and developed in pure water. Features of higher quality can be obtained when the resist is cast from 2‐methoxyethanol, probably because side reactions such as partial hydrolysis of the pendant oxazoline rings in aqueous environments are avoided. It was possible to resolve micrometer scale patterns using ca. 200 mJ/cm² of irradiation at 254 nm, followed by heating 2 min at 130°C and development in water alone. Image quality and etch resistance were improved using copolymers containing up to 20 mol % of styrene repeat units. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1225–1236, 1999     

Lipase‐Catalyzed Ring‐Opening Polymerization of 3(S)‐sec‐Butylmorpholine‐2,5‐dione

Lipase‐catalyzed ring‐opening bulk polymerizations of 3(S)‐sec‐butylmorpholine‐2,5‐dione (BMD) were investigated. Selected commercial lipases were screened as catalysts for BMD polymerization at 110°C. Polymerizations catalyzed with 10 wt.‐% of lipase PPL and PC result in BMD conversions of about 70% and in molecular weights of the products ranging from 5 500 to 10 700. Lipases MJ, CR and ES showed lower catalytic activities for the polymerization of BMD. Poly(3‐sec‐butylmorpholine‐2,5‐dione) has a carboxylic acid group at one end and a hydroxy group at the other end. During the polymerization racemization of the isoleucine residue takes place. Lipase PPL was selected for a more detailed study. The apparent rate of polymerization increases with increasing PPL concentration when the polymerization temperature is 110°C. When the PPL concentration is 5 and 10 wt.‐% with respect to the monomer, a conversion of about 70% is reached after 5 d and 3 d, respectively, while for a PPL concentration of 1 wt.‐% the conversion is less than 7% even after 6  d. High concentrations of PPL (10 wt.‐%) result in high M_n values (< 4  d). The highest molecular weight poly(BMD), M_n = 19 900, resulted from a polymerization conducted at 120°C with 5 wt.‐% PPL for 6 d. The general trend observed by varying the polymerization temperature is as follows: (i) monomer conversion and M_n increase with increasing reaction temperature from 110 to 125°C, (ii) monomer conversion and M_n decrease with an increase in reaction temperature from 125 to 130°C. Water content was found to be an important factor that controls both the conversion and the molecular weight. With increasing water content, enhanced polymerization rates are achieved while the molecular weight of poly(BMD) decreases.     

Synthesis of photoreactive polyimide having indan structure

Polyimide containing an indan unit and alkyl moiety with a high molecular weight was prepared from 5,7‐diamino‐1,1,4,6‐tetramethylindan and 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride. This polyimide was amorphous and soluble in common organic solvents, such as tetrahydrofuran, chloroform, and cyclopentanone. Thermogravimetry of the polyimide showed good thermal stability, indicating that a 10% weight loss of the polyimide was observed at 500 °C in nitrogen. The glass‐transition temperature of the polyimide was not observed by DSC measurement between room temperature and 400 °C at a heating rate of 10 °C/min (Apparatus: DSC3100 MAC Science Co., Ltd.). Transparency of the polyimide at 365 nm was 80%. The polyimide acted as a photosensitive resist of negative type by UV radiation. The resist had a sensitivity of 31 mJ/cm² and a contrast of 2.3 when it was developed with cyclopentanone at room temperature. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 423–428, 2002     

New base‐soluble positive‐working photosensitive polyimides having o‐nitrobenzyl ester group

A new positive‐working polyimide having photosensitive o‐nitrobenzyl ester group as side substituent, poly{1,4‐phenyleneoxy‐1,4‐phenylene‐3,6‐di[4‐(o‐nitrobenzyloxy)carbonylphenyl]pyromellitimide} (ODA‐PI‐Nb), was prepared and its aqueous alkali‐developability and photosensitivity were investigated. ODA‐PI‐Nb was synthesized by the esterification reaction of poly[1,4‐phenyleneoxy‐1.4‐phenylene‐3,6‐di(4‐carboxylphenyl)pyromellit imide] (ODA‐PI) with o‐nitrobenzyl bromide in the presence of triethylamine (Et₃N). ODA‐PI‐Nb obtained was characterized by FT‐IR and ¹H‐NMR spectroscopy. The degree of esterification reaction was found from ¹H‐NMR absorption of CH₂ proton to be over 95 mol%. Upon photo‐irradiation ODA‐PI‐Nb transformed to the freely aqueous alkali‐soluble ODA‐PI under formation of o‐nitrosobenzaldehyde. The thickness loss of thin ODA‐PI‐Nb films upon post‐baking at 400°C was in the 10–15% range. ODA‐PI‐Nb showed positive‐tone behavior in characteristic sensitivity curve and positive patterns were obtained using a typical lithographic process using aqueous tetramethylammonium hydroxide developer. The patterns with excellent resolution were observed and evaluated by optical microscopy and scanning electron microscopy. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis and properties of ortho‐linked aromatic polyimides based on 1,2‐bis(4‐aminophenoxy)‐4‐tert‐butylbenzene

A bis(ether amine) containing the ortho‐substituted phenylene unit and pendant tert‐butyl group, 1,2‐bis(4‐aminophenoxy)‐4‐tert‐butylbenzene, was synthesized and used as a monomer to prepare polyimides with six commercial dianhydrides via a conventional two‐stage procedure. The intermediate poly(amic acid)s had inherent viscosities of 0.78–1.44 dL/g, and most of them could be thermally converted into transparent, flexible, and tough polyimide films. The inherent viscosities of the resulting polyimides were in the range of 0.46–0.87 dL/g. All polyimides were noncrystalline, and most of them showed excellent solubility in polar organic solvents. The glass‐transition temperatures of these polyimides were in the range of 222–259 °C in differential scanning calorimetry and 212–282 °C in thermomechanicl analysis. These polyimides showed no appreciable decomposition up to 500 °C in thermogravimetric analysis in air or nitrogen. A comparative study of the properties with the corresponding polyimides without pendant tert‐butyl groups derived from 1,2‐bis(4‐aminophenoxy)benzene is also presented. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1551–1559, 2000     

Solid‐state polymerization of 2,3,6,7,10,11‐hexa(methacrylate) triphenylene

A new monomer, 2,3,6,7,10,11‐hexa(methacrylate) triphenylene (HMTP), and its crystals have been successfully synthesized, and the solid‐state polymerization under UV irradiation has been investigated. The photo polymerization of HMTP in solid was confirmed by the reduction of vinyl bonds in the FT‐IR and UV spectra of PHMTP in comparison with the corresponding spectra of its precursor. Thus, IR spectroscope was used to follow the polymerization of HMTP crystals under UV irradiation, and kinetic studies show a first‐order reaction with rate constant of 6.12 × 10^?3 min^?1. This value is slightly larger than that measured by the weight method. The polarizing optical microscope and X‐ray diffraction were used to study the crystal structure difference between the polymers and its monomer. The results show that the polymers' crystals obtained from photo polymerization kept the monomer crystal lattice. Because of strong overlap between the π‐electron of the triphenylene, the monomer and polymer crystals showed different fluorescence properties. All these results proved that the photo polymerization of HMTP crystals is governed by the packing structure of monomer molecules; in other words, this reaction is just lattice controlled polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1526–1534, 2005     

Photoimageable polyimides derived from α,α‐(4‐amino‐3,5‐dimethylphenyl)phenylmethane and aromatic dianhydride

Soluble and inherent photoimageable polyimides with improved photopatterning features were prepared from α,α‐(4‐amino‐3,5‐dimethylphenyl)phenylmethane and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride. The polyimides possessed good combined chemical and physical properties: thermal stability was observed, with an initial thermal decomposition temperature of 565 °C and a high glass‐transition temperature of 318 °C. Homogeneous polyimide solutions in common organic solvents with solid contents as high as 20 wt % were prepared. These solutions had a shelf life greater than 3 months. The polyimides had high electric insulating properties and low dielectric constants and dissipation factors. Fine patterns were processed by direct exposure of the polyimide coatings to UV i‐line, followed by development with an organic developer. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3012–3020, 2002     

Photocurable and thermally stable polymers based on 1,4‐pentadien‐3‐one‐1‐p‐hydroxyphenyl‐5‐p‐phenyl methacrylate: Copolymerization with ethyl acrylate

1,4‐Pentadien‐3‐one‐1,5‐bis(p‐hydroxyphenyl) (PBHP) was prepared by reacting p‐hydroxybenzaldehyde and acetone in the presence of an acid catalyst. 1,4‐Pentadiene‐3‐one‐1‐p‐hydroxyphenyl‐5‐p‐phenyl methacrylate (PHPPMA) monomer was prepared by reacting PBHP dissolved in ethyl methyl ketone (EMK) with methacryloyl chloride in the presence of triethylamine. A free‐radical solution polymerization technique was used for synthesizing homo‐ and copolymers of different feed compositions of PHPPMA and ethyl acrylate (EA) in EMK as a solvent with benzoyl peroxide as a free‐radical initiator at 70 ± 1 °C. All the polymers were characterized with IR and ¹H NMR techniques. The compositions of the copolymers were determined with the ¹H NMR technique. The copolymer reactivity ratios were evolved with Kelen–Tudos (EA = 1.25 and PHPPMA = 0.09) and extended Kelen–Tudos (EA = 1.30 and PHPPMA = 0.09) methods. Q (0.48) and e (1.68) values for the new monomer (PHPPMA) were calculated with the Alfrey–Price method. UV absorption spectra for poly(PHPPMA) showed two absorption bands at 302 and 315 nm. The photocrosslinking properties of the polymer samples were examined with the solvent method. Thermal analyses of the polymers were performed with the thermogravimetric‐differential thermogravimetric technique. First, the decomposition temperatures started for poly(PHPPMA), copoly(EA‐PHPPMA) (62:38), and copoly(EA‐PHPPMA) (41:59) were at 350, 410, and 417 °C, respectively. A gel permeation chromatographic method was used for determining the polymer molecular weights (weight‐average molecular weight: 2.67 × 10⁴ and number‐average molecular weight: 1.41 × 10⁴) and polydispersity index (1.89). The solubility of the monomer and the copolymers occurred at 30 °C with solvents having different polarities. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1632–1640, 2003     

Synthesis and NMR characterization of 6‐Phenyl‐6‐deoxy‐2,3‐di‐O‐methylcellulose

Cellulose ( 1 ) was converted for the first time to 6‐phenyl‐6‐deoxy‐2,3‐di‐O‐methylcellulose ( 6 ) in 33% overall yield. Intermediates in the five‐step conversion of 1 to­ 6 were: 6‐O‐tritylcellulose ( 2 ), 6‐O‐trityl‐2,3‐di‐O‐methylcellulose ( 3 ), 2,3‐di‐O‐methylcellulose ( 4 ); and 6‐bromo‐6‐deoxy‐2,3‐di‐O‐methylcellulose ( 5 ). Elemental and quantitative carbon‐13 analyses were concurrently used to verify and confirm the degrees of substitution in each new polymer. Gel permeation chromotography (GPC) data were generated to monitor the changes in molecular weight (DP_w) as the synthesis progressed, and the compound average decrease in cellulose DP_w was ～ 27%. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to characterize the decomposition of all polymers. The degradation temperatures ( °C) and percent char at 500 °C of cellulose derivatives 2 to 6 were 308.6 and 6.3%, 227.6 °C and 9.7%, 273.9 °C and 30.2%, 200.4 °C and 25.6%, and 207.2 °C and 27.0%, respectively. The glass transition temperature (T_g) of­6‐O‐tritylcellulose by dynamic mechanical analysis (DMA) occurred at 126.7 °C and the modulus (E′, Pa) dropped 8.9 fold in the transition from ?150 °C to + 180 °C (6.6 × 10⁹ to 7.4 × 10⁸ Pa). Modulus at 20 °C was 3.26 × 10⁹ Pa. Complete proton and carbon‐13 chemical shift assignments of the repeating unit of the title polymer were made by a combination of the HMQC and COSY NMR methods. Ultimate non‐destructive proof of carbon–carbon bond formation at C6 of the anhydroglucose moiety was established by generating correlations between resonances of CH₂6 (anhydroglucose) and C1′, H2′, and H6′ of the attached aryl ring using the heteronuclear multiple‐bond correlation (HMBC) method. In this study, we achieved three major objectives: (a) new methodologies for the chemical modification of cellulose were developed; (b) new cellulose derivatives were designed, prepared and characterized; (c) unequivocal structural proof for carbon–carbon bond formation with cellulose was derived non‐destructively by use of one‐ and two‐dimensional NMR methods. Copyright © 2002 John Wiley & Sons, Ltd.     

Synthesis and properties of fluorinated polyimides based on 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐2,5‐di‐tert‐butylbenzene and various aromatic dianhydrides

A novel fluorinated diamine monomer, 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)‐2,5‐di‐tert‐butylbenzene ( 2 ), was prepared through the nucleophilic substitution reaction of 2‐chloro‐5‐nitrobenzotrifluoride and 2,5‐di‐tert‐butylhydroquinone in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. Fluorinated polyimides ( 5a – 5f ) were synthesized from diamine 2 and various aromatic dianhydrides ( 3a – 3f ) via thermal or chemical imidization. These polymers had inherent viscosities of 0.77–1.01 dL/g. The 5 series polyimides were soluble in N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, and N,N‐dimethylformamide and were even soluble in dioxane, tetrahydrofuran, and dichloromethane. 5 (C) showed cutoff wavelengths between 363 and 404 nm and yellowness index (b*) values of 6.5–40.2. The polyimide films had tensile strengths of 93–114 MPa, elongations to break of 9–12%, and initial moduli of 1.7–2.1 GPa. The glass‐transition temperatures were 255–288 °C. The temperatures of 10% weight loss were all above 460 °C in air or nitrogen atmospheres. In comparison with a nonfluorinated polyimide series based on 1,4‐bis(4‐aminophenoxy)‐2,5‐di‐tert‐butylbenzene, the 5 series showed better solubility and lower color intensity, dielectric constants, and moisture absorption. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2272–2284, 2004     

Synthesis and characterization of poly(1,4‐bis((E)‐2‐(3‐dodecylthiophen‐2‐yl)vinyl)benzene) derivatives

New amorphous semiconducting copolymers, poly(9,9‐dialkylfluorene)‐alt‐(3‐dodecylthienyl‐divinylbenzene‐3‐dodecylthienyl) derivatives (PEFTVB and POFTVB), were designed, synthesized, and characterized. The structure of copolymers was confirmed by H NMR, IR, and elemental analysis. The copolymers showed very good solubility in organic solvents and high thermal stability with high T_g of 178–185 °C. The weight average molecular weight was found to be 107,900 with polydispersity of 3.14 for PEFTVB and 76,700 with that of 3.31 for POFTVB. UV–vis absorption studies showed the maximum absorption at 428 nm (in solution) and 435 nm (in film) for PEFTVB and at 430 nm (in solution) and 436 nm (in film) for POFTVB. Photoluminescence studies showed the emission at 498 nm (in solution) and 557 nm (in film) for PEFTVB and at 498 nm (in solution) and 536 nm (in film) for POFTVB. The solution‐processed thin‐film transistors showed the carrier mobility of 2 × 10^?4 cm² V^?1 s^?1 for PEFTVB‐based devices and 2 × 10^?5 cm² V^?1 s^?1 for POFTVB‐based devices. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3942–3949, 2010