A positive‐working photosensitive polyimide based on thermal cross‐linking and acidolytic cleavage

A novel positive‐working photosensitive polyimide (PSPI) based on a poly(hydroxyimide) (PHI), a crosslinking agent having vinyl ether groups, and a photoacid generator (PAG) was prepared. The PHI as a base resin of the three‐component PSPI was synthesized from 4,4′‐oxydiphthalic anhydride and 2,2′‐bis(3‐amino‐4‐hydroxyphenyl)hexafluoropropane through ring‐opening polymerization and subsequent thermal cyclization. 2,2′‐bis(4‐(2‐(vinyloxy)ethoxy)phenyl)propane (BPA‐DEVE) was used as a vinylether compound and diphenyliodonium 5‐hydroxynaphthalene‐1‐sulfonate was used as a PAG. The phenolic hydroxyl groups of the PHI and the vinyl ether groups of BPA‐DEVE are thermally crosslinked with acetal structures during prebake step, and the crosslinked PHI becomes completely insoluble in an aqueous basic solution. Upon exposure to UV light (365 nm) and subsequent postexposure bake (PEB), a strong acid generated from the PAG cleaves the crosslinked structures, and the exposed area is effectively solubilized in the alkaline developer. The dissolution behavior of the PSPI containing each 11.5 wt % of BPA‐DEVE and of the PAG was studied after UV exposure (365 nm) and PEB. It was found that the difference in dissolution rates between exposed and unexposed areas was enough to get high resolution. A fine positive pattern with a resolution of 5 μm in a 3.7‐μm‐thick film was obtained from the three‐component PSPI. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A fluorescent chemosensor based on optically active 2,2′‐binaphtho‐20‐crown‐6 for metal ions

A chiral conjugated polymer can be obtained by the polymerization of (S)‐6,6′‐dibromo‐2,2′‐binaphtho‐20‐crown‐6 and 1,4‐divinyl‐2,5‐dibutoxybenzene via a palladium‐catalyzed Heck cross‐coupling reaction. The chiral conjugated polymer shows strong green‐blue fluorescence. The responsive properties of the chiral polymer to metal ions were investigated using fluorescence and UV‐visible absorption spectra. K⁺, Pb²⁺, Cd²⁺ and Ba²⁺ enhance the fluorescence of the polymer; in contrast, Hg²⁺ causes effective quenching of the fluorescence of the polymer. The obvious influences on the fluorescence indicate that the 2,2′‐binaphtho‐20‐crown‐6 moiety plays an important role in fluorescence recognition for Hg²⁺ due to the effective photo‐induced electron transfer or charge transfer between the conjugated polymer backbone and the receptor ions. The responsive properties of the polymer to metal ions show that the chiral conjugated polymer incorporating 2,2′‐binaphtho‐20‐crown‐6 moieties in the main‐chain backbone as recognition sites can act as an excellent fluorescent probe for the sensitive detection of Hg²⁺. Copyright © 2010 Society of Chemical Industry     

Synthesis and characterization of novel dihydrobenzoxazine resins

Three dihydrobenzoxazines are synthesized from bisphenol A (BPA), 4,4′‐biphenol (BIP), and dicyclopentadiene phenol adduct (DCPD). Polydihydrobenzoxazine containing 4,4′‐biphenol (BIPDB) had the most rigid structure of the three and was found to possess the best mechanical and thermal properties. The glass transition temperature of BIPDB was 206°C, and that of BPA‐type polydihydrobenzoxazine (BPADB) and dicyclopentadiene type polydihydrobenzoxazine (DCPDDB) were 184 and 183°C, respectively. DCPDDB, with a rigid hydrophobic cycloaliphatic structure, was found to possess excellent properties such as low moisture absorption, low dielectric constant, low polarization. The resulted polymer from DCPDDB had a dielectric constant of 2.94U, which was better than that of polymers derived from BPA (3.31U), BIP (3.45U), and traditional phenolic resin (3.9–4.0U). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 342–347, 2006     

Structural effects of pendant groups on thermal and electrical properties of polyimides

Two series of aromatic polyimides containing various‐sized alkyl side groups were synthesized by thermal imidization of the poly(amic acid)s prepared from the polyaddition of benzophenonetetracarboxylic dianhydride and hexafluoro‐isopropylidene bis(phthalic anhydride) with 4,4′‐methylenedianiline, 4,4′‐methylene‐bis(2,6‐dimethylaniline), 4,4′‐methylene‐bis(2,6‐diethylaniline), and 4,4′‐methylene‐bis(2,6‐diisopropylaniline). The extent to which alkyl substitutes affect the thermal properties of polyimides was examined by differential scanning calorimetry, thermomechanical analyzer, and thermogravimetric analysis techniques. The analytical results demonstrated that the incorporation of alkyl moieties causes a moderate increase in the coefficient of thermal expansion and a slight decrease in thermal stability. Notably, all polymers had a decomposition temperature exceeding 500°C. The glass transition temperature increases markedly when hydrogen atoms at ortho positions on aniline rings are replaced with methyl groups, but decreases with growing alkyl side group size. The dielectric measurements show that the polymer possessing a large alkyl side group would have the lower dielectric value. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4672–4678, 2006     

Wavelength‐shift fluorescent probes for monitoring of polymerization

The feasibility of using wavelength‐shift fluorescent probes for cure monitoring of an epoxy resin and an acrylic resin was evaluated. 4‐(N,N‐dihexylaminostyryl)‐4′‐pyridinium propylsulfonate (DHASP‐PS), as well as each of other wavelength‐shift fluorescent probes, was dissolved in the epoxy resin, a stoichiometric mixture of diglycidyl ether of bisphenol A and 4,4′‐methylene‐bis(cyclohexylamine). The fluorescence and the excitation spectra of each of the probes dissolved in the epoxy resin were then measured at various times during the cure of the epoxy resin at 60°C. The fluorescence and the excitation spectra of the probe DHASP‐PS dissolved in methyl methacrylate (MMA) were also measured at various times during the cure of the acrylic resin at 55°C. Since the peak fluorescence wavelength of each of the wavelength‐shift fluorescent probes decreased during the cure of the epoxy resin or MMA, these fluorescent probes can be used for monitoring the polymerization reactions of epoxy resins and vinyl resins. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 747–750, 2006     

季铵盐类荧光增白剂的合成及性能

三聚氯氰与4,4′-二氨基二苯乙烯-2,2′-二磺酸和两种氨基化合物经过三步缩合反应得到三嗪基氨基二苯乙烯型荧光增白剂,用三乙醇胺和三乙胺分别替代二乙醇胺和二乙胺,合成新型两性季铵盐类荧光增白剂,研究其与对比的非季铵盐类荧光增白剂的应用性能和在水溶液中的紫外吸收性能、光致异构化现象、荧光发射性能及其应用性能.结果表明：该季铵盐类增白剂耐酸碱性能明显提高,使用范围扩大,但其紫外吸收和荧光发射性能下降,且同样存在较为明显的光致异构化现象,耐光性也较差.     

Synthesis,characterization, and photophysics of a novel conjugated polymer with 1,3,4‐oxadiazole,carbazole, and naphthalene units

A polymer containing 1,3,4‐oxadiazole and carbazole units in the main chain and naphthalene moieties as side groups (P‐OCN) was synthesized by the Wittig reaction of [2,5‐bis(3‐tolylene)1′,3′,4‐oxadiazole]‐9‐(α‐naphthyl)‐carbazole polymer (P‐OCN). The optical properties were investigated with ultraviolet–visible absorption and fluorescence emission spectra. The results showed that the luminescence quantum yield of P‐OCN was 0.673 in chloroform, and it emitted blue and blue‐green light with a band gap of 3.49 eV estimated from the onset absorption. Thermogravimetric analysis and differential scanning calorimetry showed that the polymer exhibited good thermal stability up to 354°C with a glass‐transition temperature higher than 110°C. To investigate the donating and accepting capacities of P‐OCN, the fluorescent quenching technique was used to determinate the interactions between the polymer and the electron donor and electron acceptor. The results showed that the light emission could be quenched by both the electron donor (N,N‐dimethylaniline) and electron acceptor (dimethylterephthalate). Furthermore, the interaction between P‐OCN and fullerene was also studied with fluorescent quenching, and the processes followed the Stern–Volmer equation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

New light emitting materials: Alternating copolymers with hole transport and emitting chromophores

A new type of novel high‐efficiency light‐emitting nitrogen‐containing poly(phenylene vinylene) (PPV)‐related copolymers, which have hole‐transfer moieties such as triphenylamine (TPA) and conjugated aromatic units such as 4,4′‐biphenylene, 1,4‐phenylene, 2,5‐dimethyl‐1,4‐phenylene, 1,4‐ or 1,5‐naphthylene, and 9,10‐anthrylene, was designed and synthesized by the well‐known Wittig–Hornor reaction. The resulting alternating copolymers were highly soluble in common organic solvents. They can spin‐cast onto various substrates to give highly transparent homogeneous thin films without heat treatment. The introduction of TPA units in the PPV backbone improved processibility and limited the π‐conjugation length. Furthermore, the additional π‐electron delocalization between the lone‐paired electron in the nitrogen atom and π‐electrons in the conjugated units contributed to the improvement of the fluorescence quantum yields of these copolymers. All these alternating copolymers except TPA–PAV have high‐efficiency photoluminescence and they are very promising for light‐emitting diodes (LEDs). It is very promising that TPA–PAV will emit white light when used in LED device due to the broad emission spectra. The origin of the broad spectrum is contributed by the charge‐transfer complex formation, which can be proved by the absorption and emission spectra of TPA–PAV solutions. When the aromatic units were 1,4‐phenylene, 1,4‐ or 1,5‐naphthylene, 4,4′‐biphenylene, and 9,10‐anthrylene, respectively, with increase of the capability to accept electrons in aromatic units, the charge transfer from TPA to aromatic units occurred; consequently, the fluorescence quantum yield decreased. The introduction of the alkoxy‐substitute group on the aromatic units in the polymer backbone caused the red shift of the absorption and emission spectra of the copolymers due to the stronger delocalization of the π‐conjugated system. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3351–3358, 1999     

Preparation and characterization of green reflective films of polyaniline analogs containing azobenzene units

Pd‐catalyzed polycondensation of aniline derivatives and 4,4′‐dibromoazobenzene affords polyaniline analogs containing azobenzene units. The polymers are red in solution and in thin films state, whereas they have a green luster in thick films. Substitution of 4,4′‐dibromoazobenzene for 4,4′‐dibromostilbene changes the reflection color from green to blue, whereas the introduction of a non‐conjugated unit slightly affects the reflection color. The glossiness of the film is dependent on the smoothness of the film surface. The reflectance measurements using polarized light reveal that reflection spectra correlate well with the complex refractive index (ñ = n + ik) of the film. These results confirm that the green luster can be attributed to the uniform surface reflection of the object, which has a large refractive index and absorption coefficient at around 500 nm. The polymer films exhibit good transmission of radio frequency signals owing to the lack of free electron carriers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41275.     

Preparation of monodisperse fluorescent core–shell polymer microspheres with functional groups in the shell layer by two‐stage distillation–precipitation polymerization

Monodisperse crosslinked core–shell micrometer‐sized microspheres bearing a brightly blue fluorescent dye, carbazole, and containing various functional groups in the shell layers were prepared by a two‐stage distillation–precipitation polymerization in acetonitrile in the absence of any stabilizer. Commercial divinylbenzene (DVB), containing 80 vol.% of DVB, was polymerized by distillation–precipitation in acetonitrile without any stabilizer using 2,2′‐azobisisobutyronitrile (AIBN) as the initiator for the first stage of polymerization which resulted in monodisperse polyDVB microspheres used as the core. Several functional monomers, including 2‐hydroxyethyl methacrylate and acrylonitrile together with N‐vinylcarbazole blue fluorescent comonomer, were incorporated into the shell layers with AIBN as initiator during the second stage of polymerization. The resultant core–shell polymer microspheres were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, UV‐visible spectroscopy and fluorescence spectroscopy. Copyright © 2006 Society of Chemical Industry     

Synthesis of novel optically active poly(ester imide)s by direct polycondensation reaction promoted by tosyl chloride in pyridine in the presence of N,N‐dimethyformamide

4,4′‐Hexafluoroisopropylidene‐2,2‐bis(phthalic acid anhydride) (1) was treated with L ‐methionine (2) in acetic acid and the resulting 4,4′‐(hexafluoroisopropylidene)‐N,N′‐bis(phthaloyl‐L ‐methionine) diacid (4) was obtained in high yields. The direct polycondensation reaction of this diacid with several aromatic diols, such as bisphenol A (5a), phenolphthalein (5b), 1,4‐dihydroxybenzene (5c), 4,4′‐dihydroxydiphenyl sulfide (5 d), 4,6‐dihydroxypyrimidine (5e), 4,4′‐dihydroxydiphenyl sulfone (5f), and 2,4′‐dihydroxyacetophenone (5g), was carried out in a system of tosyl chloride (TsCl), pyridine (Py), and N,N‐dimethylformamide (DMF). The reactions with TsCl were significantly promoted by controlling alcoholysis with diols, in the presence of catalytic amounts of DMF, to give a series of optically active poly(ester imide)s, (PEI)s, with good yield and moderate inherent viscosity ranging from 0.43 to 0.67 dL/g. The polycondensation reactions were significantly affected by the amounts of DMF, molar concentration of monomers, TsCl and Py, aging time, temperature, and reaction time. All of the aforementioned polymers were fully characterized by ¹H NMR, FTIR, elemental analysis, and specific rotation. Some structural characterization and physical properties of these optically active PEIs are reported. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 455–460, 2006     

Synthesis of a bifunctional epoxy monomer containing biphenyl moiety and properties of its cured polymer with phenol novolac

A new type of epoxy resin containing a 4,4′‐biphenylene moiety in the backbone (Bis‐EBP) is synthesized and confirmed by elemental analysis, infrared spectroscopy, and ¹H‐nuclear magnetic resonance spectroscopy. In addition, to evaluate the influence of the 4,4′‐biphenylene group in the structure, an epoxy resin having a 1,4‐phenylene group in place of the 4,4′‐biphenylene moiety (Bis‐EP) is synthesized. The cured polymer obtained through the curing reaction between the new biphenyl‐containing epoxy resin and phenol novolac is used for making a comparison of its thermal and physical properties with those obtained from Bis‐EP and bisphenol‐A (4,4′‐isopropylidenediphenyl)‐type epoxy resin (Bis‐EA). The cured polymer obtained from Bis‐EBP shows markedly higher fracture toughness of 1.32 MPa m^1/2, higher glass transition temperature, lower moisture absorption, and higher thermal decomposition temperature. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 690–698, 1999     

How the monomer concentration of polymerization influences various properties of polybenzimidazole: A case study with poly(4,4′‐diphenylether‐5,5′‐bibenzimidazole)

In this work, a series of poly(4,4′‐diphenylether‐5,5′‐bibenzimidazole)s (OPBIs) were synthesized from 4,4′‐oxybis(benzoic acid) and 3,3′,4,4′‐tetraaminobiphenyl through the variation of the initial monomer concentration with a solution polycondensation technique in a poly(phosphoric acid) medium. The resulting polymers were characterized by various techniques such as infrared (IR), nuclear magnetic resonance, dynamic mechanical analysis (DMA), and thermogravimetric analysis. The initial monomer concentration in the polymerization mixture played an important role in controlling the molecular weight of the resulting polymers. A temperature‐dependent IR study showed that the free movement of the ? NH group of the imidazole ring was blocked by the absorbed moisture. The DMA study showed that the glass‐transition temperature (T_g) varied with the molecular weight, and the presence of the ether linkage in the OPBI polymer backbone had a significant influence on T_g. A high‐molecular‐weight OPBI polymer tended to form a supramolecular organization, which influenced the thermal characteristic of the polymer. Photophysical studies demonstrated the fluorescent characteristics of the OPBI polymers in both solid and solution states. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Photopolymerization of acrylate derivatives initiated by hexaarylbiimidazole with ether groups

A novel hexaarylbiimidazole derivative 2,2′‐bis‐(2‐chlorophenyl)‐4,4′,5,5′‐tetra‐[3‐(2‐hydroxyl‐3‐ethylene glycol monoethylene ether‐propane‐1‐oxy)‐phenyl]‐1,2′‐biimidazole (BCTE‐HABI) was synthesized from 3,3′‐dihydroxyl benzil. Ultraviolet spectra, fluorescence spectra, ESR measurements, photo‐dilatometer experiments and photo‐DSC measurements indicated its good UV‐visible absorption ability, high photolysis efficiency and efficient photo‐initiation for acrylates. Copyright © 2006 Society of Chemical Industry     

Structural investigations and swelling behavior of 6FDA copolyimide thin films

The effects of swelling on chain distance, free volume size and orientation of functional groups of copolyimides containing carboxyl groups were examined using wide‐angle X‐ray diffraction (WAXD), positron annihilation lifetime spectroscopy (PALS) and Fourier transform infrared (FTIR) spectroscopy. A 2,3‐dimethylbenzothiophene/n‐dodecane mixture (0.3 wt%/99.7 wt%) was used as a swelling agent, as it is a binary model mixture to investigate membrane‐based desulfurization of kerosene. Thin film samples were prepared from copolyimide structures which had been synthesized via a polycondensation reaction of 4,4′‐hexafluoroisopropylidene di(phthalic anhydride), 3,5‐diaminobenzoic acid, 2,3,5,6‐tetramethyl‐1,4‐phenylenediamine and 2,4,6‐trimethyl‐1,3‐phenylenediamine. A relationship between a lower amount of 3,5‐diaminobenzoic acid present in the copolyimide backbone and a higher amount of solvent sorption in the film was found. This was attributed to the fact that the carboxyl groups on the polymer backbone can form hydrogen bonds, reducing sorption and swelling phenomena. PALS measurements for the different structures showed significantly smaller hole sizes for the free volume sites of the copolyimide containing fewer carboxyl groups. Although WAXD of film samples after time‐dependent swelling indicated that the chain distance initially decreased slightly, FTIR experiments using polarized light did not show any significant orientation changes in the polymer chains. Copyright © 2011 Society of Chemical Industry     

Polyphenylquinoxalines containing pendant phenylethynyl groups: Preliminary mechanical properties

Polyphenylquinoxalines (PPQ's) containing various amounts of crosslinkable pendant phenylethynyl groups were prepared from the reaction of 3,3′,4,4′-tetraaminodiphenyl ether, 4,4′-oxydibenzil, and 4,4′-oxybis(4″-phenylethynylbenzil). The distribution of the pendant phenylethynyl groups along the polymer chain was varied in an attempt to alter the properties of the polymers. Preliminary film, adhesive, and laminate properties of PPQ void of pendant crosslinkable groups and containing pendant phenylethynyl groups were determined. The thermally induced reaction of the phenylethynyl group crosslinked the polymer which resulted in better dimensional stability at elevated temperatures.     

Synthesis and properties of new polyurethanes with triazene moieties in the main chain

A new diol with bistriazene groups, 1,1′[4,4′‐diphenylether]‐3,3′‐di(β‐hydroxyethyl methyl)‐bistriazene (BTD), was synthesized and characterized. BTD, along with N‐methyldiethanolamine as a chain extender, was used to prepare a segmented polyurethane based on poly(tetramethylene oxide) diol (weight‐average molecular weight = 2000) and 2,4‐tolylene diisocyanate (80:20 v/v 2,4‐/2,6‐isomer mixture). Subsequent quaternization of the amine with benzyl chloride formed the cationomer. The structure–property relationships, including the photochemical behavior of the triazene linkage in these polymers, were investigated with respect to another polyurethane prepared from 4,4′‐diphenylmethane diisocyanate and a bistriazene compound. Photolysis experiments were carried out in polymer solutions and in the film state, and the reduction of the π–π* absorption band, characteristic of the triazene chromophore in ultraviolet spectra, was followed. A kinetic evaluation revealed a first‐order photoprocess. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 385–391, 2005     

Highly fluorinated poly(ether‐imide)s derived from 2,2′‐bis(3,4,5‐trifluorophenyl)‐4,4′‐diaminodiphenyl ether and aromatic dianhydrides

A new diamine, 2,2′‐bis(3,4,5‐trifluorophenyl)‐4,4′‐diaminodiphenyl ether (FPAPE) was synthesized through the Suzuki coupling reaction of 2,2′‐diiodo‐4,4′‐dinitrodiphenyl ether with 3,4,5‐trifluorophenylboronic acid to produce 2,2′‐bis(3,4,5‐trifluorophenyl)‐4,4′‐dinitrodiphenyl ether (FPNPE), followed by palladium‐catalyzed hydrazine reduction of FPNPE. FPAPE was then utilized to prepare a novel class of highly fluorinated all‐aromatic poly(ether‐imide)s. The chemical structure of the resulting polymers is well confirmed by infrared and nuclear magnetic resonance spectroscopic methods. Limiting viscosity numbers of the polymer solutions at 25 °C were measured through the extrapolation of the concentrations used to zero. M_n and M_w of these polymers were about 10 000 and 25 000 g mol^?1, respectively. The polymers showed a good film‐forming ability, and some characteristics of their thin films including color and flexibility were investigated qualitatively. An excellent solubility in polar organic solvents was observed. X‐ray diffraction measurements showed that the fluoro‐containing polymers have a nearly amorphous nature. The resulting polymers had T_g values higher than 340 °C and were thermally stable, with 10% weight loss temperatures being recorded above 550 °C. Based on the results obtained, FPAPE can be considered as a promising design to prepare the related high performance polymeric materials. Copyright © 2011 Society of Chemical Industry     

Two‐component photoresists containing thermally crosslinkable photoacid generators

Bis{4‐[2′‐(vinyloxy)ethoxy]phenyl}‐4‐methoxyphenylsulfonium triflate (TPS‐2VE‐Tf) and tris{4‐[2′‐(vinyloxy)ethoxy]phenyl}sulfonium triflate (TPS‐3VE‐Tf) were synthesized as thermally crosslinkable photoacid generators (PAGs) and used in a two‐component chemically amplified photoresist system. The photoresist films formulated with poly(p‐hydroxystyrene) (PHS) as a binder polymer and a thermally crosslinkable PAG are insolubilized in aqueous base by prebaking due to the thermal crosslinking reaction between PHS and the PAG. The insolubilization temperature of the resists and conversion of vinyl ether groups are greatly influenced by the PAG concentration and prebaking temperature, respectively. Upon exposure to deep UV and subsequent postexposure bake, the crosslinks are cleaved by photogenerated acid, leading to effective solubilization of the exposed areas. Photoresists containing TPS‐2VE‐Tf and TPS‐3VE‐Tf exhibited sensitivities of 12 and 45 mJ/cm², respectively. Positive‐tone images were obtained using a 2.38 wt% aqueous tetramethylammonium hydroxide developer.