Synthesis and properties of organosoluble polyimides based on novel perfluorinated monomer hexafluoro-2,4-toluenediamine

New highly fluorinated aromatic polyimides based on hexafluoro-2,4-toluenediamine and commercially available dianhydrides (6FDA and ODPA) were synthesized by one-pot high temperature polycondensation in benzoic acid melt. Owing to the CF₃ group and fluorine atoms in the meta-linked phenylenediamine fragment, these polyimides combine good solubility in organic solvents including such a low boiling point solvent as chloroform with high glass transition temperatures (330-345 °C), thermal and thermooxidative stability (T₅ is >500 °C). The highly fluorinated polyimide films (hydrogen content is ≤1%) exhibit good dielectric properties and low water absorption as well as excellent optical transparency in the UV-vis region (cut-off wavelength is 311 nm for 6FDA-based and 357 nm for ODPA-based polyimides), which is very important for optoelectronic materials.     

Heat-resistant and soluble fluorinated poly(amide imide)s based on non-coplanar ortho-linked diimide-dicarboxylic acid

A series of novel fluorinated heat-resistant poly(amide imide)s (PAIS) based on non-coplanar diimide-diacid monomer (DIDA) were synthesized and characterized. The poly(amide imide)s were obtained in high yields and possessed inherent viscosities in the range of 0.47-0.91 dL g⁻¹. All of the polymers were amorphous in nature, showed outstanding solubility and could be readily soluble in common organic solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidinoned, dimethyl sulfoxide, N,N-dimethylformamide, pyridine and tetrahydrofuran. Glass transition temperatures were in the range of 221-263 °C, as determined by differential scanning calorimetry. Degradation temperatures for 10% weight loss occurred all above 520 °C and char yields was more than 50% at 700 °C in nitrogen atmosphere. Moreover, these PAIs possessed low refractive indexes (n = 1.58-1.59), birefringence (Δn = 0.008-0.013), and dielectric constants (? ≈ 2.5) due to the trifluoromethyl pendent groups and ortho-catenated aromatic rings that interrupt chain packing and increase free volume.     

Synthesis and characterization of organosoluble polyamides from quinoxaline based diamine

<正>Aromatic/aliphatic polyamides were synthesized from a diamine monomer,2,3-bis-p-aminophenylquinoxaline (Ⅳ),based on quinoxaline and various dicarboxylic acids of aliphatic,aromatic and heterocyclic.The diamine and polyamides were characterized by elemental analysis,FTIR and ~1H-NMR.The solubility of the polyamides was affected by the quinoxaline and heterocyclic groups in the polymer chain.They were all soluble in common organic solvents such as dimethylsulfoxide(DMSO),N,N-dimethylformamide(DMF) and N-methylpyrolidone(NMP).The polyamides showed inherent viscosity in the range of 0.25-0.3 dL/g in DMSO at 25℃and good thermal stability with the char yields in the range of 65%-82%at 600℃in nitrogen.     

Synthesis and characterization of novel fluorinated polyimides derived from 1,1′-bis(4-aminophenyl)-1-(3-trifluoromethylphenyl)-2,2,2-trifluoroethane and aromatic dianhydrides

A novel fluorinated aromatic diamine 1,1′-bis(4-aminophenyl)-1-(3-trifluoromethylphenyl)-2,2,2-trifluoroethane (6FDAM) was synthesized in a simple procedure, which was then employed to prepare a series of fluorinated polyimides with commercial aromatic dianhydrides, such as pyromellitic dianhydride (PMDA), 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane (6FDA), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and 4,4′-oxydiphthalic anhydride (ODPA). The polyimides exhibited good solubility in strong dipolar solvents such as NMP, DMAc, DMF and m-cresol as well as some of low boiling point organic solvents of THF and CHCl₃, etc. Experimental results indicated the polyimides possessed low moisture adsorptions of 0.42-0.95%, low dielectric constant of 2.71-2.95 at 1 MHz, high dielectric strength of 92.0-122.6 kV/mm and good optical transparency with cutoff wavelengths of UV-vis at 330-375 nm. The polyimides also exhibited good mechanical properties as well as excellent thermal and thermo-oxidative stability. The fluorinated polyimides possessed better solubility, lower dielectric constant and water adsorption as well as higher optical transparency than the representative non-fluorinated polyimide derived from PMDA and 4,4′-oxydianiline (ODA).     

High solubility and optical transparency of novel polyimides containing 3,3′,5,5′-tetramethyl pendant groups and 4-tert-butyltoluene moiety

A series of novel polyimides (3a–d) were prepared from 3,3′,5,5′-tetramethyl-4,4′-diaminodiphenyl-4”-tert-butyltoluene (1) with four aromatic dianhydrides via a one-step high-temperature polycondensation procedure. The obtained polyimides showed excellent solubility, with the dissolvability at a concentration of 10 wt% in most amide polar solvents and chlorinated solvents. Their films were nearly colorless and exhibited high optical transparency, with the UV cutoff wavelength in the range of 322–350 nm and the wavelength of 80% transparency in the range of 395–414 nm. They also showed low dielectric constant (2.72–2.91 at 1 MHz) and low water absorptions (0.37–0.62%). Moreover, these polyimides possessed high glass transition temperatures (T_g) (above 321 °C) and good thermal stability with 10% weight loss temperatures in the range of 526–547 °C in nitrogen atmosphere. In comparison with the analogous polyimides non-containing 3,3′,5,5′ -tetramethyl pendant groups, the resultant polyimides 3a–d showed better solubility, higher optical transparency and lower dielectric constant.     

High optical transparency and low dielectric constant of novel organosoluble poly(ether ketone amide)s derived from an unsymmetrical diamine containing trifluoromethyl and methyl pendant groups

A series of novel fluorinated poly(ether ketone amide)s (PEKAs) were prepared from an unsymmetrical aromatic diamine, (4′-(4″-amino-2″-trifluoromethylphenoxy)-3′,5′-dimethylphenyl)(4-aminophenyl)-methanone (1), with various aromatic dicarboxylic acids using the phosphorylation polycondensation technique. The PEKAs had inherent viscosities ranging from 0.43 to 0.65 dl/g. All the fluorinated PEKAs could be soluble in many polar organic solvents such as N-methyl-2-pyrrolidinone (NMP), N,N′-dimethylacetamide (DMAc), N,N′-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and tetrahydrofuran (THF). Flexible and tough polymer films could be prepared by casting from DMAc solvent. The PEKA films exhibited high optical transparency with a cutoff wavelength of 354–365 nm and good mechanical properties with tensile strengths of 78–98 MPa and elongations at break of 11.5–18.5%. They showed glass-transition temperatures in the range of 288−323 °C and the onset decomposition temperatures in the range of 450−461 °C in nitrogen atmosphere. Meanwhile, the PEKA films possessed low dielectric constants of 1.98–2.71 at 1 MHz and low moisture absorption (<2%). Due to their properties, the fluorinated PEKAs could be considered as photoelectric and microelectronic materials.     

Studies on novel thermally stable segmented polyurethanes based on thiourea-derivative diols

Novel thermoplastic segmented poly(urethane-thiourea)s (PURs) were synthesized via one-step polymerization from aromatic diols containing sulfur (thiourea linkage) in the main-chain, including terephthaloyl bis (3-(2-hydroxopyridyl) thiourea) (TBHPT) and terephthaloyl bis (3-(5-naphtholyl) thiourea) (TBNT), along with 1,4-phenylene diisocyanate (PDI) as hard segment and 20, 50 and 80 mol% polyethylene glycol (PEG) as a soft segment. The prepared chain extenders and polymers were characterized by conventional methods, and physical properties such as η_inh, solubility, thermal stability and thermal behavior were studied. Easily processable PURs with excellent thermal stability were obtained by incorporating 20 mol% PEG in the soft segment. Thermogravimetric analysis indicated that poly(urethane-thiourea)s were fairly stable above 500 °C and own high glass transition temperatures about 263-266 °C. These polymers also showed partially crystalline structures. Ultimately, weight average molecular weights (M_w) of PURs were up to 109 × 10³. Compared to typical polyurethanes, PURs exhibited better thermal stability and T_g’s owing to rigid hard segment structure.     

Effects on the thermal expansion coefficient and dielectric properties of CLST/PTFE filled with modified glass fiber as microwave material

The CLST/PTFE/5%GF composite sharply decreases the CTE in both X&Y and Z directions, obtained a promising microwave dielectric material for microwave communication.     

A novel class of organosoluble and light-colored fluorinated polyamides derived from 2,2-bis(4-amino-2-trifluoromethylphenoxy)biphenyl or 2,2-bis(4-amino-2-trifluoromethylphenoxy)-1,1-binaphthyl

Two series of novel fluorinated aromatic polyamides were prepared from 2,2^′-bis(4-amino-2-trifluoromethylphenoxy)biphenyl (2) and 2,2^′-bis(4-amino-2-trifluoromethylphenoxy)-1,1^′-binaphthyl (4) with various aromatic dicarboxylic acids using the phosphorylation polycondensation technique. The polyamides had inherent viscosities ranging from 0.43 to 0.62 dl/g and 0.36 to 0.74 dl/g, respectively. All the fluorinated polyamides were soluble in many polar organic solvents such as N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidinone, and afforded transparent, light-colored, and flexible films upon casting from DMAc solvent. These polyamides showed glass-transition temperatures in the ranges of 190-240 °C (for the 6 series from diamine 2) and 247-255 °C (for the 7 series from diamine 4) by differential scanning calorimetry, softening temperatures in the ranges of 196-230 °C (6 series) and 241-291 °C (7 series) by thermomechanical analysis, and decomposition temperatures for 10% weight loss above 420 °C in both nitrogen and air atmospheres.     

含有联苯结构的高含氟量聚芳醚的制备

<正>聚芳醚(PAEs)具有优异的热稳定性和力学强度,已在航空航天、汽车和生物材料等获领域得了重要应用~([1,2]).将具有一定作用的功能性基团,如—F,—SO3H和—C≡CH等,引入到PAEs分子链中使这类材料获得特殊的性能是高性能高分子材料研究领域的重要课题~([3~5]).以Teflon~和Nafion~为代表的含氟聚合物在不粘涂层、燃料电池用质子交换膜和高效气体分离~([6~8])     

Aromatic polyimides with tertbutyl-substituted and pendent naphthalene units: synthesis and soluble,transparent properties

A novel non-coplanar aromatic diamine monomer,3,3'-ditertbutyl-4,4'-diaminodiphenyl-4'-naphthylmethane(TAPN) was synthesized by a condensation reaction of 2-tertbutylaniline and 1-naphthaldehyde under catalyst hydrochloric acid.The structure of the monomer was confirmed by FTIR,NMR,elementary analysis and mass spectrometry.A series of aromatic polyimides(PIs) were synthesized via conventional one-step polycondensation from TAPN and various commercial aromatic dianhydrides.All of the PIs exhibit excellent solubility in common organic solvents,even in low boiling point solvents such as chloroform(CHCl3),tetrahydrofuran(THF) and acetone.The PIs present outstanding thermal stability with the glass transition temperature(Tg) ranged from 299 °C to 350 °C,and the temperature at 10% weight loss ranged from 490 °C to 504 °C,and high optical transparency with the cutoff wavelengths of 306-356 nm.Moreover,the flexible and tough PI films have prominent mechanical properties with tensile strengths in the range of 77.6-90.5 MPa,tensile modulus in the range of 1.8-2.4 GPa and elongation at break in the range of 6.3%-9.5%,as well as lower dielectric constant(2.89-3.12 at 1 MHz) and lower moisture absorption(0.35%-0.66%).     

Compositional effect of ZrO2 nanofillers on a PVDF-co-HFP based polymer electrolyte system for solid state zinc batteries

Composite polymer electrolytes(CPEs) comprising poly(vinilydene fluoride-hexafluoro propylene), PVDF-coHFP and zinc triflate, Zn(CF3SO3)2 with varying concentrations of ZrO_2 nanofillers were prepared by solution casting technique with N,N-dimethyl formamide(DMF) as the common solvent. The polymer electrolyte specimen with the particular composition 75 wt% PVDF-co-HFP: 25 wt% Zn Tf + 7 wt% Zr O2 showed the highest conductivity of 4.6 × 10-4 S/cm at 298 K as confirmed from impedance measurements and favored by the rich amorphous phase of the CPE revealed from room temperature X-ray diffraction analysis(XRD). The electrical conductivity relaxation time and its distribution within the materials have been evaluated from the electric modulus M 2 and impedance Z" data which showed the occurrence of non-Debye type of relaxation phenomenon. The changes in the surface morphology of the CPEs were examined using scanning electron microscopy(SEM). The electrochemical stability window of CPE is found to be 2.6 V with a thermal stability up to 300 °C. An electrochemical cell has been fabricated based on Zn/MnO_2 electrode couple under a constant load of 1 MΩ and its discharge characteristics have been evaluated.     

A novel route for synthesizing esters and polyesters from the Diels-Alder adduct of levopimaric acid and acrylic acid

A novel route for the esterification of the Diels-Alder adduct between abietic acid, in its isomer form of levopimaric acid, and acrylic acid was established. The high purity Diels-Alder adduct was prepared starting from rosin acids. When the adduct was subjected to a condensation reaction in the presence of a cyclic carbonate ester and of an efficient amine catalyst, hydroxyalkyl esters were obtained. The corresponding linear polyesters were synthesized by the advanced polycondensation of the above intermediates at high temperature, under vacuum, and in the presence of some adequate polyesterification catalysts. In the work 1,3-dioxolan-2-one as cyclic carbonate ester, triethylamine as esterification catalyst, and toluene-4-sulfonic acid monohydrate or tetrabutyl titanate as polycondensation catalysts, were preferred for exemplifications. The polyesters were soluble in dimethylacetamide, trichloromethane, tetrahydrofuran, 1,1,2,2-tetrachloroethane, or 1,4-dioxane. The thermal and electric studies showed that the polymers were substances with good thermal stability and high dielectric properties.     

Synthesis and characterization of novel fluorinated polyimides derived from 4-phenyl-2,6-bis[4-(4′-amino-2′-trifluoromethyl-phenoxy)phenyl]pyridine and dianhydrides

A series of organo-soluble polyimides were prepared from a novel fluorinated diamine monomer, 4-phenyl-2,6-bis[4-(4′-amino-2′-trifluoromethylphenoxy)phenyl]pyridine and various commercial aromatic dianhydrides. These polyimides had good solubility in common organic solvents. The obtained strong and flexible PI films exhibited excellent thermal stability with the decomposition temperature (at 5% weight loss) of above 561 °C and the glass transition temperature in the range of 258-312 °C. Moreover, the polymer films showed good electrical insulating property, low dielectric constant and low water uptake due to the introduction of fluorinated substitutes in the polymer backbone. The remarkable combined features ensure these polymers to be ideal candidate materials for advanced microelectronic industry and other related applications.     

Synthesis and properties of novel organosoluble polyimides derived from bis[3-(4-amino-2-trifluoromethylphenoxy) phenyl] ether

A new aromatic ether diamine, bis[3-(4-amino-2-trifluoromethylphenoxy) phenyl] ether, was successfully synthesized via nucleophilic substitution reaction of 3,3′-oxydiphenol and 2-chloro-5-nitrotrifluoromethylbenzene, followed by a catalytic reduction. A series of new polyimides were synthesized from the diamine with various commercially available aromatic dianhydrides via a conventional two-stage process, i.e. ring-opening polyaddition forming the poly(amic acid)s and further thermal or chemical imidization forming polyimides. The resulting polyimides exhibited good solubility in polar solvents, such as N,N-dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidinone and common solvents such as chloroform, tetrahydrofuran upon heating and possessed the inherent viscosities of 0.51-0.68 dL/g. The resulting strong and flexible films exhibited excellent thermal stability with the temperature at 10% weight loss is above 502 °C and the glass transition temperature in the range of 191-232 °C. The polyimides also were found to possess high optical transparency.     

High Tg and high organosolubility of novel polyimides containing twisted structures derived from 4-(4-amino-2-chlorophenyl)-1-(4-aminophenoxy)-2,6-di-tert-butylbenzene

A series of new polyimides (PIs) containing di-tert-butyl side groups were synthesized via the polycondensation of 4-(4-amino-2-chlorophenyl)-1-(4-aminophenoxy)-2,6-di-tert-butylbenzene (3) with various aromatic tetracarboxylic dianhydrides. The introduction of the asymmetric di-tert-butyl groups and twisted-biphenyl structures is an effective way to increase the inter chain distance and decrease the intermolecular interaction and packing ability of the resulted polymers. Thus, these novel PIs exhibited low dielectric constants (2.83-3.10), low moisture absorption (0.95-1.69%), excellent solubility, and high glass transition temperatures (307-456 °C). The PIs derived from the new diamine and the rigid pyromellitic dianhydride (PMDA) were soluble in N-methyl-2-pyrrolidinone, N,N-dimethylacetamide, tetrahydrofuran, m-cresol, and cyclohexanone. The polymers also show good retention of storage modulus at high temperature (325 °C). In addition, ¹H NMR spectrum of the diamine 3 revealed that the protons of 4-aminophenoxy moiety are not chemical shift equivalent.     

Synthesis and characterization of Schiff-base-containing polyamides

A series of new Schiff base polyamides（PAs） were synthesized by polycondensation of benzilbisthiosemicarbazone diamine（LH₆） with different commercially available aliphatic and aromatic diacid chlorides. The monomer and all the PAs were characterized by FTIR,¹H-NMR,and elemental analysis.The prepared polyamides showed inherent viscosities in the range of 0.30-0.36 dL/g in DMF at 25℃,indicating their moderate molecular weight.The PAs were completely soluble in aprotic polar solvents such as dimethylformamide（DMF）,N-methylpyrolidone（NMP）, tetrachloroethane（TCE）,dimthylsulfoxide（DMSO） and also in H₂SO₄ and partially soluble in THF,acetone and chloroform at room temperature.Thermal analysis showed that these PAs were practically amorphous and exhibited 10%weight loss above 220℃.     

功能化苯并咪唑类离子液体的合成及性质

合成了一系列由磺酸基、 羧基修饰的新型功能化苯并咪唑类离子液体, 采用IR, ¹H NMR, ¹³C NMR和ESI-MS对其结构进行了表征, 研究了化合物的热稳定性、 电导率以及室温下在各种溶剂中的溶解性等性质. 结果表明, 该类离子液体在 280 ℃以下基本没有失重, 热稳定性较好; 在水溶液浓度为1×10^-3 mol/L时, 随着温度的升高, 电导率几乎与温度呈正比增大; 能与大多数有机溶剂互溶, 溶解性随着溶剂极性的增加而增大.     

Synthesis and characterization of novel polybenzimidazoles containing 4-phenyl phthalazinone moiety

A novel series of homo- and copoly(phthalazinone benzimidazole)s were synthesized from various stoichiometric mixtures of 4-(4-(4-(4-carboxyphenoxy)phenyl)-1-oxophthalazin-2(1H)-yl)benzoic acid (CPPBC) and isophthalic acid (IPA) with 3,3′-diaminobenzidine (DAB) by solution polycondensation in polyphosphoric acid (PPA). The structures of the obtained polymers were characterized by FT-IR and ¹H NMR. The obtained polybenzimidazoles were found to be soluble in aprotic polar solvents such as N-methyl-2-pyrolidinone (NMP), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO) and m-cresol, without the addition of inorganic salts. The inherent viscosities of the polybenzimidazoles were in the range of 1.10–2.05 dL/g. All of the polymers show amorphous nature as evaluated by WAXD. These polymers have high glass transition temperatures (T_gs) in the range of 398–408 °C. Thermogravimetric analysis exhibit that these polybenzimidazoles containing 4-phenyl phthalazinone moiety have excellent thermal stability with the temperatures for 5% and 10% weight loss of the polymers ranging from 516 to 594 °C and 560 to 672 °C, respectively.     

Preparation and characterization of polyimide/mesoporous silica hybrid nanocomposites based on water-soluble poly(amic acid) ammonium salt

Recently, mesoporous silica was blended with polyimide to develop low dielectric constant (k) materials with improving mechanical and thermal properties of polyimide by utilizing both the nanoporous structure and silica framework. However, even the use of mesoporous silica did not show a significant decrease of k due to the phase segregation in between polyimide and the mesoporous silica materials. In this work, we attempted to prepare polyimide/mesoporous silica hybrid nanocomposites having relatively good phase mixing behavior by utilizing polyimide synthesized from a water soluble poly(amic acid) ammonium salt, which lead to low k up to 2.45. The thermal properties of polyimide were improved by adding mesoporous silicas. For this work, we have fabricated mesoporous silicas through surfactant-templated condensation of tetraethyl orthosilicate (TEOS). Pyromellitic dianhydride (PMDA)-4,4′-oxydianiline (ODA) polyimide was prepared from poly(amic acid) ammonium salt, which had been obtained by incorporating triethylamine (TEA) into PMDA-ODA poly(amic acid) in dimethylacetamide (DMAc), followed by thermal imidization.