Alkaline-developable and negative-type photosensitive polyimide with high sensitivity and excellent mechanical properties using photo-base generator

An alkaline developable and negative-type PSPI with a high sensitivity and excellent mechanical properties based on a poly(amic acid) (PAA) and a photo-base generator has been developed. The PAA was prepared by the polycondensation of p-phenylenediamine (PDA) with an equimolar of 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA) and converted thermally to the corresponding polyimide, PI(PDA-BPDA/6-FDA). PI(PDA-BPDA/6-FDA) showed the high thermal and mechanical properties and the dimensional stability such as the thermal decomposition temperature of 530°C, glass transition temperature of 369°C, linear coefficient of thermal expansion of 28 ppm/K, ultimate tensile strength of 148 MPa, elongation at break of 25% and dielectric constant of 2.8. The PSPI was formulated directly from PAA(PDA-BPDA/6-FDA) with a photo-base generator (PBG), (E)-3-(2-hydroxy-4-methoxyphenyl)-1-(piperidin-1-yl)prop-2-en-1-one (HMPP) (10 wt% to PAA) and the optimized parameters for photolithographic process were investigated including the PBG content, post-exposure bake (PEB) temperature, and PEB time. The PSPI based on PAA(PDA-BPDA/6-FDA) and HMPP (10 wt% to PAA) showed a sensitivity of 114 mJ/cm² and contrast of 1.29 when exposed to 365-nm light (i-line), post-exposure baked at 160°C for 5 min, and developed with an aqueous solution of 2.38 wt% tetramethylammonium hydroxide and iso-propanol. A clear negative 8-μm features pattern was obtained by contact-printing and converted into the PI pattern upon heating at 250°C, confirming by scanning electron microscopy and infrared spectroscopy.     

Poly(imide ether sulphone) as new soluble high performance polymer

Poly(imide ether sulphone) as novel high-performance polymer has been obtained by the condensation polymerization of 4,4'-bis(4-fluorophthalimido) diphenyl ether with 4,4'-sulfonyldiphenol via aromatic nucleophilic substitution reaction. Its structure was confirmed by means of FTIR and NMR spectroscopy, elemental analysis. Differential scanning calorimetry and thermal analysis measurements showed that synthesized polymer possessed high glass transition temperature (T_g = 210°C) and good thermal stability with high decomposition temperatures (T_d > 480°C). Prepared polymer film showed good light transmittance and mechanical strength.     

Synthesis and properties of novel colorless and thermostable polyimides containing cross-linkable bulky tetrafluorostyrol pendant group and organosoluble triphenylmethane backbone structure

A colorless and high temperature resistant fluorinated polyimide (PI) film based on a novel cross-linkable diamine monomer 4,4′-diamino-4″-(2,3,5,6-tetrafluoro-4-ethylenephenoxy) triphenylmethane (DFPTM) was successfully prepared. The special triphenylmethane backbone and the bulky tetrafluorostyrol pendant group in DFPTM gave the PI material eximious solubility in organic solvents, high tensile properties, good thermal stability, and excellent optical transparency (cutoff wavelength for 331 nm and light transmittance above 94% at 450 nm). Furthermore, the styryl could initiate self-crosslinking reaction to form a dense three-dimensional network structure by thermal curing. Hence, the cross-linked PI film showed superior combination property (including excellent resistance to solvents). It's T_g increased by 57.1–306.0°C, the 5% thermal weight-loss temperature improved by 10.2% to 500.0°C, and the tensile strength enhanced by 17.5% to 39.7 MPa. Moreover, after thermal curing, the cross-linked PI attained a lower elongation at break from 8.1 to 3.9%, and the thermal expansion coefficient reduced from 82.2 to 68.8 ppm/°C without obvious loss of optical transparency (cutoff wavelength for 347 nm and light transmittance remained 93.0% at 450 nm).     

High thermal stable polyimide resins derived from phenylethynyl-endcapped fluorenyl oligoimides with low melt viscosities

To improve the processability and thermal stability of polyimide, a series of novel phenylethynyl-endcapped oligoimides(PEPA-oligoimides) with calculated molecular weights(M_nC) were successfully prepared from thermal imidization of 4,4'-(9-fluorenylidene) dianiline(BAFL) as fluorenyl diamine, 4,4′-oxy-diphthalic anhydride(ODPA) as aromatic dianhydride and 4-phenylethynylphthalic anhydride(4-PEPA) acted as reactive end-capping reagent at elevated temperatures. Experiment results indicated that the oligoimides were the mixtures of PEPA-endcapped oligomers with different degrees of polymerization characterized by MALDI-TOF mass spectra. The influence of chemical structures on the melt processabilities of the oligoimides, the thermal, dielectric and mechanical properties of the thermoset resins was studied. The typical oligoimide resin owned minimum melt viscosity of 0.2 Pa·s at around 310 °C and wide melting processing window, suitable for resin transfer molding(RTM). Besides, its corresponding thermal-cured polyimide resin possessed glass transition temperature(T_g) as high as 514 °C. The dielectric constants of polyimide resins decreased from 3.15 to 2.80 by reducing the M_nC. The mechanical properties of the polyimide neat resins were improved gradually with increasing MnC. Finally, the carbon fiber/polyimide(C_f/PI) composite laminates showed excellent mechanical strength retention rate at 350 °C, might be long-term served at extremely high temperature in aerospace and aviation field.     

Phthalonitrile‐containing aromatic polyimide thin films with nano‐actuation properties

Polymer films of some polyimides containing pendant phthalonitrile groups were prepared by casting the corresponding poly(amic acid) solutions onto glass plates, followed by thermal imidization under controlled temperature conditions. The poly(amic acid)s were synthesized by polycondensation reaction of 4,4′‐diamino‐4″‐(3,4‐dicyanophenoxy)triphenylmethane, 1, or of different amounts of 1 and 4,4′‐bis(4‐aminophenoxybiphenyl), with two aromatic dianhydrides, 4,4′‐oxydiphthalic anhydride or benzophenone‐3,3′,4,4′‐tetracarboxylic dianhydride. Most of the films were flexible and tough and exhibited high thermal stability, having the initial decomposition temperature above 400 °C. Dynamic mechanical analysis and dielectric spectroscopy revealed the influence of phthalonitrile group content on the relaxation processes of polyimides. The values of the dielectric constant at 10 kHz and 20 °C were in the range of 3.25–3.61. The films exhibited nano‐actuation in the range of 240–480 nm, depending on the phthalonitrile group content, when an electric voltage was applied on their surface. Copyright © 2012 John Wiley & Sons, Ltd.     

Biaspartimide-diamines as Curing Agents for Epoxy Resins

Various 4,4′ -bis(N²-[4-(4-aminophenoxy)phenyl]aspartimido)diphenylmethane-type bisaspartimide-diamines have been used as solventless curing agents for epoxy resins. The thermal curing was performed at 170, 190, and 230°C to give a tough brown polymer. Thermogravimetric analysis of the polymer obtained showed thermal stability up to 330°C and char yields of 45% in N₂ at 800°C and 12% in air at 700°C. The thermal curing reaction was monitored using FT-IR. The synthesized polymers are useful for making composites, laminates, and adhesives.     

Colorless polyimide nanocomposite films containing hexafluoroisopropylidene group

Poly(amic acid) (PAA) was prepared by the reaction of 4,4'‐(hexafluoro‐isopropylidene)diphthalic anhydride (6FDA) with 2,2'‐bis[4‐(4‐aminophenoxy)phenyl] hexafluoropropane (BAPP) in N,N‐dimethylacetamide (DMAc). Hybrid films were obtained from blend solutions of the precursor polymer and the organoclay Cloisite 15A, varying the organoclay content from 0 to 3.0 wt%. The cast PAA film was heat‐treated at different temperatures to create polyimide (PI) hybrid films, which showed excellent optical transparencies and were almost colorless. The intercalation of PI chains in the organoclays was examined by means of wide‐angle X‐ray diffraction (XRD) and electron microscopy (SEM and TEM). In addition, the thermo‐mechanical properties were tested using a differential scanning calorimeter (DSC), a thermogravimetric analyzer (TGA), and a universal tensile machine (UTM). In the XRD, SEM, and TEM results for the PI hybrid films, a substantial increase in the agglomeration of the clay particles was observed as the clay loading was increased from 0.5 to 3.0 wt%. This suggests that in the hybrid materials with low clay content, the clay particles are better dispersed in the matrix polymer and do not agglomerate significantly. We found that the addition of a small amount of organoclay is sufficient to improve the thermal and mechanical properties of the PI, with the maximum enhancement being observed at 1.0 wt% Cloisite 15A. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis,Structures and Properties of Polyimide Based on 2,2′‐Bis(4‐aminophenoxy phenyl) Propane

2,2‐Bis[4‐(4‐aminophenoxy)phenyl] propane (BAPP), as a monomer to prepare polyimide, was synthesized from Bisphenol A and p‐chloronitrobenzene via the nucleophilic substitution reaction. The structures of the diamine monomer BAPP and an intermediate dinitrocompound 2,2′‐bis(4‐nitrophenoxy phenyl) propane (BNPP) were confirmed by FTIR and NMR. A novel polyimide was derived from BAPP and 3,3′,4,4′‐oxydiphthalic dianhydride (ODPA) in DMAc by a two‐step method. FTIR, DSC, TGA, and DMA were employed to characterize the precursor and the polyimide. The glass transition temperature of the polyimide was about 225–230°C. The measurement of mechanical properties indicated that the polyimide exhibited a typical yield behavior of thermoplastic polymers, which is very different from other polyimides. The elongation at break of the polyamic acid and polyimide was 6% and 29%, respectively.     

Amine–quinone polyimides

Two dianiline monomers were prepared by the reaction of either 4,4′‐methylenedianiline or 4,4′‐oxydianiline with 1,4‐benzoquinone. These monomers were used to synthesize a series of amine–quinone polyimides by condensation with either 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride or 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride to make the corresponding polyamic acid. The polyamic acids were converted to the polyimides by thermal imidization at 290 °C. The amine–quinone polyimides gave freestanding films with tensile strengths in the range of 90 to 150 MPa and Young's moduli of 0.9 to 1.5 GPa. The thermal decomposition temperature under nitrogen was 440 to 480 °C and the glass‐transition temperature was in the range of 280 to 310 °C. The amine–quinone polyimides had the excellent thermal and mechanical properties that one expects for polyimides. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4044–4049, 2001     

Influence of temperature and imidization method on the structure and properties of polyimide fibers prepared by wet spinning

A polyamic acid (PAA) based on 4,4′-bis(4-aminophenoxy)diphenyldiamine and 1,3-bis-(3′,4-dicarboxyphenoxy)benzene dianhydride was synthesized. PAA fibers were prepared by wet spinning. Subsequent cyclization of PAA units was achieved using chemical or thermal imidization. The influence of the imidization method and process conditions on the chemical structure, porosity, morphology, thermal and mechanical properties of polyimide (PI) fibers was studied. Thermal imidization was carried out in the temperature range from 60 to 300 °C at different process durations. The degree of imidization of PI fibers was studied by IR spectroscopy. The structure and properties of PI fibers were studied by scanning electron microscopy, thermal analysis, and by measuring the stress-strain properties.

     

引入不对称结构对聚酰亚胺模塑料加工性能的改善

采用联苯四酸二酐（BPDA）与4,4′-二胺基二苯醚(4,4′-ODA)和3,4′-二胺基二苯醚(3,4′-ODA)聚合后,经亚胺化,制备了一系列二胺不同配比的高强度易加工的聚酰亚胺模塑料。 并对其流变性能、力学性能及热学性能进行测试。 结果表明,随着3,4′-ODA含量的增加模塑料的冲击强度没有大的改变,而流变性能随3,4′-ODA含量的增加而提高,w(3,4′-ODA)在50%时,玻璃化转变温度为275 ℃,材料的冲击强度为141 kJ/m2。 模压压力为20 MPa时加工性能优异。     

New polymer electrolyte membrane for medium-temperature fuel cell applications based on cross-linked polyimide Matrimid and hydrophobic protic ionic liquid

New hydrophobic protic ionic liquid, 2-butylaminoimidazolinium bis(trifluoromethylsulfonyl)imide (BAIM-TFSI), has been synthesized. The ionic liquid showed good thermal stability to at least 350 °C. The conductivity of BAIM-TFSI determined by electrochemical impedance method was found to be 5.6 × 10^?2 S/cm at 140 °C. Homogeneous composite films based on commercial polyimide (PI) Matrimid and BAIM-TFSI containing 30–60 wt% of ionic liquid were prepared by casting from methylene chloride solutions. Thermogravimetric analysis data indicated an excellent thermal stability of PI/BAIM-TFSI composites and thermal degradation points in the temperature range 377 °C–397 °C. The addition of ionic liquid up to 50 wt% in PI films does not lead to any significant deterioration of the tensile strength of the polymer. The dynamic mechanical analysis results indicated both an increase of storage modulus E′ of PI/BAIM-TFSI composites at room temperature and a significant E′ decrease with temperature compared with the neat polymer. The cross-linking of the PI with polyetheramine Jeffamine D-400 allowed to prepare PI/Jeffamine/BAIM-TFSI (50%) membrane with E′ value of 300 MPa at 130 °C. The ionic conductivity of this cross-linked composite membrane reached the level of 10^?2 S/cm at 130 °C, suggesting, therefore, its potential use in medium-temperature fuel cells operating in water-free conditions.     

Thermal properties of polyimide system containing silicone segments

The influence of the structure properties relationships of silicone incorporated polyimide (PI) on thermal stability was investigated by using single scan thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) in nitrogen. Four systems have been synthesized based on monomer 4-(4-(1-(4-(4-aminophenoxy) phenyl)-1-methylethyl) phenoxy) aniline (BAPP)/3,3??,4,4??-Biphenyltetracarboxylic dianhydride including parent PI (S-1), PI siloxane copolymer (S-2 and S-3), and PI siloxane hybrid (S-4). The derivative thermogravimetric analysis (DTG) and DSC curves indicate a double and single stage decomposition process and glass transition temperature (T _g), respectively. While the PI, PIS, and PSH showed distinctive features towards thermal analysis, it was found that the rate of degradation (???/??t) was influenced by the flexibility of Si?CO?CSi in the backbone and in Si?CO?CSi itself. These results revealed that the presence of Si?CO?CSi in either the backbone or matrix indicates its stability with regard to high thermal service applications.     

New organosoluble polyimides with low dielectric constants derived from bis[4-(2-trifluoromethyl-4-aminophenoxy)phenyl] diphenylmethylene

A new kink diamine with trifluoromethyl group on either side, bis[4-(2-trifluoromethyl-4-aminophenoxy)phenyl]diphenylmethane (BTFAPDM) , was reacted with various aromatic dianhydrides to prepare polyimides via poly (amic acid) precursors followed by thermal or chemical imidization. Polyimides were prepared using 3,3′, 4,4′-biphenyltetracarboxylic dianhydride(1), 4,4′-oxydiphthalic anhydride(2), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (3), 4,4′-sulfonyldiphthalic anhydride(4), and 4,4′-hexafluoroisopropylidene-diphathalic anhydride(5). The fluoro-polyimides exhibited low dielectric constants between 2.46 and 2.98, light color, and excellent high solubility. They exhibited glass transition temperatures between 227 and 253°C, and possessed a coefficient of thermal expansion (CTE) of 60-88 ppm/°C. Polymers PI-2, PI-3, PI-4, PI-5 showed excellent solubility in the organic solvents: N-methyl-2-pyrrolidinone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), pyridkie and tetrahydrofuran (THF). Inherent viscosity of the polyimides were found to range between 0.58 and 0.72 dLg-1. Thermogravimetric analysis of the polyimides revealed a high thermal stability decomposition temperature in excess of 500°C in nitrogen. Temperature at 10 % weight loss was found to be in the range 506-563°C and 498-557°C in nitrogen and air, respectively. The polyimide films had a tensile strength in the range 75-87 MPa; tensile modulus, 1.5-2.2 GPa; and elongation at break, 6-7%.     

Preparation and characterization of polyimide/pure silica zeolite hybrid films

In this study, amino derivative of pure silica zeolite nanocrystal (A‐PSZN) was dispersed into polyimide (PI) matrix to prepare PI/A‐PSZN hybrid films, and their thermal and mechanical properties, as well as hydrophobicity, were characterized scientifically. The test results show that PI/A‐PSZN hybrid films possess higher glass transition temperature, higher thermal stability and lower in‐plane coefficient of thermal expansion than pristine PI. The mechanical property data suggest that the incorporation of A‐PSZN results in an increase in Young's modulus and tensile strength of the hybrid films, but as its content exceeds the critical value (maybe 5 wt%), its enhancement effect on the hybrid's strength and toughness gets weaker. Furthermore, liquid dripping imaging analysis results indicate that the film's hydrophobicity is clearly improved by the introduction of A‐PSZN. As compared with PSZN, A‐PSZN exhibits better effect on enhancing the overall performance of pristine PI films. A comparison with other studies suggests that PI/A‐PSZN is a hybrid film with superior comprehensive properties. Copyright © 2013 John Wiley & Sons, Ltd.     

Fluorinated polyimide/POSS hybrid polymers with high solubility and low dielectric constant

A series of fluorinated polyimide/POSS hybrid polymers(FPI-4-FPI-16) were prepared via a facile synthetic route using 2,2'-bis(trifluoromethyl)benzidine, 4,4'-oxydiphthalic dianhydride and monofunctional POSS as starting materials. The hybrid polymers showed excellent solubility and film formation ability. Flexible and robust hybrid films could be conveniently obtained via solution-casting. The hybrid films demonstrated low dielectric constants and high thermal stability. Their dielectric constants were in the range of 2.47–2.92 at 1 MHz measured for their capacitance, and were tunable and decreased with an increase of POSS content. Their 10% weight loss temperatures were in the range of 539-591 ℃ and the weight residual at 800 ℃ ranged from 48% to 53% in nitrogen atmosphere. These hybrid films also possessed good mechanical properties and hydrophobic characteristics. This work could provide a potential strategy for the preparation of fluorinated polyimide/POSS hybrid polymers.     

Synthesis and Properties of Novel Thermal Stable Thermoplastic Poly(ester-imide-ether) Elastomers Based on N,N′-Bis(2-carboxyethyl)-3,3′,4,4′ Biphenyltetracarboxylimide Unit with Excellent Mechanical Properties

A series of thermoplastic poly(ester-imide-ether) (PEIE) elastomers, with different ratios of soft/hard segment 85/15, 80/20 and 70/30, were prepared from 1, 4-butanediol (BD), poly(tetramethylene glycol) (PTMG) and imide dicarboxylic acid monomer based on 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and glycine (GLY). The chemical structures of the imide dicarboxylic acid and PEIEs were characterized by FT-IR and ¹H-NMR, respectively. The intrinsic viscosities, thermal properties and mechanical properties of these PEIEs were investigated. The results show that introduction of imide group endows the PEIEs with excellent thermal stability, the melting point of PEIEs at about 220°C, and the temperature of 5% weight loss appears at the range of 332–358°C. In addition, the mechanical properties of PEIEs are also improved with the increment of imide units, the maximum stress and strain reached to 17.15 MP and 1043.75%, respectively.     

Synthesis and characterization of highly transparent and hydrophobic fluorinated polyimides derived from perfluorodecylthio substituted diamine monomers

Two new perfluorodecylthio substituted aromatic diamines, namely 2,4‐diamino‐1‐(1H,1H,2H,2H‐perfluorodecathio)benzene (DAPFB) and 2,2'‐Bis((1H,1H,2H,2H‐perfluorodecyl)thio)[1,1'‐biphenyl]4,4'‐diamine (BPFBD) were synthesized and polycondensed with 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride (6FDA) to produce two new perfluorinated polyimides (PI2 and PI4). The chemical structures of these polyimides were confirmed by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy and elemental analysis. Two other polyimides (PI1 and PI3) were also synthesized from 6FDA and analogous perfluorodecylthio unsubstituted diamines to investigate the incorporation effect of perfluorodecylthio group on various physical and chemical properties of the synthesized PIs. Compared with PI1 and PI3, PI2 and PI4 exhibited improved solubility, optical transparency, and hydrophobicity, lower moisture absorption, dielectric constant, and thermo‐mechanical stabilities owing to the presence of the perfluorodecylthio side group in the polymer chain. Even though thermo‐mechanical properties of PI2 and PI4 ( : 413 and 404 °C, T_g: 220 and 209 °C, tensile strength of 101 and 76 MPa, tensile modulus of 1.7 and 1.5 GPa and elongation at break of 8 and 10%, respectively) were reduced in comparison to PI1 and PI3 but still were good enough for most of the practical applications. Most importantly, the presence of the perfluorodecylthio side group in BPFBD considerably reduced the dielectric constant of PI4 to 2.71 which was quite low as aromatic polyimide. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 479–488     

Influence of multiple processing on selected properties of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)

The effect of multiple (up to 10 times) injection molding of processed poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P(3,4HB)) on its phase transition temperatures, degree of crystallinity, degradation temperature, mass flow rate, mechanical properties, dynamic mechanical properties, and Charpy's impact strength is presented. The studies have shown that the multiple injection lowers the degree of crystallinity and the thermal stability of P(3,4HB). The mass flow rate values increased with increasing the injection number. It was found that the multiple injections had no substantial effect on the tensile strength up to 10 injection cycles and the tensile strength at break, tensile strain at tensile strength, and tensile strain at break up to 6 injection cycles. The maximum value of storage modulus at 30 °C and impact strength were recorded for sample after 4 cycles of injection, while the values of storage modulus at 120 °C increased with increase of the injection cycles. Copyright © 2015 John Wiley & Sons, Ltd.     

Modification of acrylic bone cements by poly(ethylene glycol) with different molecular weight

The high polymerization temperature of acrylic bone cements can cause arthroplasty failure because of the thermal necrosis of surrounding bone tissue. To reduce this undesired effect we have developed novel acrylic bone cement composites containing a phase change material (PCM). As PCM poly(ethylene glycol) (PEG) of different molecular weight was applied and the effect of its incorporation on curing parameters, mechanical and morphological properties of acrylic bone cement was investigated. A significant decrease in maximum temperature from 65.8°C to 47.4°C and slight increase of setting time were observed. PEG introduction also contributed to the thermal stability of acrylic bone cement increase. SEM investigation of modified bone cement confirmed that the microstructure does not alter considerably because of PEG content. It was found that both PEG addition and incubation test contribute to an inconsiderable decrease in mechanical strength of bone cement. However, the mechanical strength increase can be caused by the fresh bone tissue incorporation into the pores appearing in bone cement. Copyright © 2016 John Wiley & Sons, Ltd.