Synthesis and properties of hyperbranched polyimides derived from novel triamine with prolonged chain segments

Novel pyridine‐containing hyperbranched polyimides (HBPIs) were synthesized by using a new triamine 2,4,6‐tris[3‐(4‐aminophenoxy)phenyl]pyridine with prolonged chain segments, ether linkage and meta‐linked units as a BB′₂‐like monomer, various commercial aromatic dianhydrides as A₂ monomers. Most of the obtained HBPIs were readily soluble in common organic solvents such as N,N‐dimethylformamide, N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidone, m‐Cresol, and so forth. Meanwhile, they also had good thermal stability with the glass transition temperatures (T_gs) all above 210 °C, the temperature at 10% weight loss of 537.1–574.4 °C in nitrogen atmosphere. Strong and flexible HBPI films were obtained, which had good mechanical properties with tensile strengths of 83.3–95.8 MPa, tensile modulus of 1.82–2.43 GPa and elongations at break of 4.84–6.98%. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2425–2437     

Gas transport properties of hyperbranched polyimide/hydroxy polyimide blend membranes

Gas transport properties of novel hyperbranched polyimide/hydroxy polyimide blends and their silica hybrid membranes were investigated. Gas permeability coefficients of the blend membranes showed positive deviation from a semilogarithmic additive rule. The enhanced gas permeability were resulted from the increase in free volume elements caused by the intermolecular interaction between terminal amine groups of the hyperbranched polyimide and hydroxyl groups of the hydroxy polyimide backbone. Additionally, CO₂/CH₄ separation ability of the blend membranes was markedly promoted by hybridization with silica. The remarkable CO₂/CH₄ separation behavior was considered to be due to characteristic distribution and interconnectivity of free volume elements created by the incorporation of silica. For the hyperbranched polyimide/hydroxy polyimide blend system, polymer blending and hybridization techniques synergistically provided the excellent CO₂/CH₄ separation ability.     

Synthesis,structure, and thermal properties of polyrotaxanes derived from β-cyclodextrin and polydimethylsiloxane

Supramolecular inclusion complexes, polyrotaxanes, of β-cyclodextrin with modified polydimethylsiloxane were prepared. The structure and thermal properties of these complexes were studied as influenced by the preparation conditions, component ratio, and molecular weight of the polymer.     

Synthesis of novel hyperbranched polyimide for liquid crystal alignment

A novel hyperbranched polyimide (HPPI) was synthesized from a new four‐functional amine and 1,2,3,4‐cyclobutanetetracarboxylic dianhydride. The polyimide with hyperbranched structure exhibited excellent alignment for nematic liquid crystal (LC) compared with traditional linear polyimides. The solution viscosities of the poly(amic acids) (PAAs) and the surface morphology of PI films were investigated using an Ubbelhode‐type viscometer and atomic force microscopy, respectively. The viscosities of the hyperbranched PAAs were much lower than that of the linear PAA solution at any monomer ratio (amine:dianhydride). Pretilt angles of LCs above 2.8° were achieved with HPPI.     

Synthesis,gas barrier and thermal properties of polyimide containing rigid planar fluorene moieties

In order to obtain pristine polyimides with high barrier properties, pyromellitic dianhydride (PMDA) and 9H-fluorene-2,7-diamine (FDA) containing rigid planar fluorene moieties were used to prepare polyimide (FPI) via a conventional two-step polymerization process in this paper. The synthesized polyimide shows good barrier properties, with oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) low to 1.01 cm³ m^?2 day^?1 and 2.35 g m^?2 day^?1, respectively. The effect of rigid planar structure in main chain on the barrier properties of polyimide was studied by means of wide angle X-ray diffractograms (WAXD), molecular dynamics simulations and positron annihilation lifetime spectroscopy (PALS), which was rarely reported before. The results reveal that the good barrier properties of FPI are mainly due to the high crystallinity, high chain rigidity and low free volume, which are resulted from the rigid planar structure. Additionally, the polyimide exhibits excellent thermal and dimensional stability with 5 wt% loss temperature of 519°C, glass transition temperature of 370°C and coefficient of thermal expansion (CTE) of 5.72 ppm/K. The good gas barrier and thermostability endow the polyimide with promising potential in flexible electronics encapsulation applications.     

Film-forming characteristics and thermal stability of low viscosity benzoxazines derived from melamine

A novel class of low-viscosity benzoxazines has been synthesized from melamine and formaldehyde with phenol or bisphenol A. The striking feature of the class of benzoxazines is the subtle combination of their inherently low viscosity at room temperature, good film-forming characteristics and high chemical and thermal stability mainly due to the introduction of melamine into the network of the polymers. The structure of the benzoxazines has been confirmed by proton nuclear magnetic resonance spectroscopy and fourier transform infrared spectroscopy. Thermal properties of polybenzoxazine have been studied by differential scanning calorimetry, dynamic mechanical analysis and thermogravimetric analysis. Transparent polybenzoxazine films were easily obtained under solvent-free conditions, exhibiting significantly improved toughness compared to the conventional polybenzoxazines. Our research may open a new path for overcoming the present drawbacks of polybenzoxazines such as high brittleness, the difficulties in preparing films and poor processibility via tailoring the structures and properties of amine in the benzoxazines.     

Synthesis of melamine based polymer complexes and their thermal degradations and magnetic properties

In this study, new polymer Fe(III) and Cr(III) complexes were synthesized. These polymer complexes were characterized by using elemental analysis, FT-IR spectroscopy, MS, thermal analyses and magnetic susceptibility measurement technics. Their thermal degradations were investigated, and co-polymerization was compared to aliphatic polymerization by using 1,2-dibromomethylbenzene and o-phenylenedialdehyde. Finally, metal ratios of the complexes were determined by using atomic absorption spectroscopy. The complexes are distorted octahedral low-spin (S = 1/2) Fe(III) and distorted octahedral (S = 3/2) Cr(III) bridged by COO^? and catechol groups.     

Synthesis and properties of hyperbranched polyamide-esters derived from 1,3,5-tris(4′-hydroxyphenylcarbamoyl)benzene

A novel aromatic triol was synthesized and polycondensed with various diacid chlorides resulting in the preparation of a series of hydroxy-terminated hyperbranched polyamide-esters without gelation. Structure and degree of branching of the ensuing polymers were confirmed by FTIR, ¹H and ¹³C NMR analyses. These thermally stable polymers were found to be soluble in aprotic solvents. Inherent viscosities and T_g values lie in the range of 0.15-0.21 dL/g and 74-112 °C, respectively.     

Synthesis,rheological, and thermal properties of waterborne hyperbranched polyurethane acrylate dispersions for UV curable coatings

A series of waterborne hyperbranched polyurethane acrylate (WHUAs) ionomers used for ultraviolet curable waterborne coatings were synthesized. The average particle size of aqueous dispersion ranged between 48.2 and 75.3 nm at 0.05% concentration determined by laser light scattering. The effects of end group of WHUAs on rheological properties were investigated. WHUAs have much lower viscosity than EB2002, commercial linear waterborne polyurethane acrylate. Moreover, the glass transition temperature (T_g) evaluated by differential scanning calorimetry of samples showed that the influence of end capping by hard segment consisting of toluene diisocyanate–hydroxyethyl acrylate is significant due to the increase of crosslink density. All cured WHUA have higher glass transition temperatures than those of cured EB2002. The results of thermogravimetric analysis for cured WHUA films indicated good thermal stability with no appreciable weight loss until 200°C, and that an increase in the hard segment content provoked the increases in thermal degradation temperature. The activation energies were calculated by Flynn–Wall method to be 91.3, 114.3, and 139.7 kJ mol⁻¹ for cured WHUA62, WHUA44, and WHUA26, with the individual ratios of 6:2, 4:4, and 2:6 for salt-like group to double bond at the terminals, compared with 81.1 kJ mol⁻¹ of EB2002 in N₂ atmosphere, respectively.     

超支化聚芴的合成与性能研究

采用2,7-二(4-羟基苯基)-9,9-二烷基芴(A2)与四对甲基苯磺酸季戊四醇酯(B4)通过A2+B4型缩聚反应合成了一系列共轭型超支化聚合物.利用紫外和荧光谱对聚合物予以表征,结果表明,此类聚合物均可发出稳定、纯正的蓝光.DSC和TGA显示,4种聚合物在150℃以下没有明显的相态变化,300℃以内无明显的热分解现象,这表明此类聚合物具有良好的热稳定性,有利于材料的发光效率及发光稳定性.     

Characterizations and thermal stability of soluble polyimide derived from novel unsymmetrical diamine monomers

Two kinds of novel aromatic, unsymmetrical diamines with ether-ketone group, 3-amino-4′-(4-amino-2-trifluoromethylphenoxy)-benzophenone and 3-amino-4′-(4-aminophenoxy)-benzophenone, was successfully synthesized by two different synthetical routes and polymerized with various aromatic tetracarboxylic acid dianhydrides, including 4,4′-oxydiphthalic anhydride, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, and 2,2′-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride, via a conventional two-step thermal or chemical imidization method to produce a series of fluorinated polyimides. The polyimides were characterized with solubility tests, viscosity measurements, mechanical properties tests, IR-FT, and thermogravimetric analysis. The polyimides had inherent viscosities of 0.54-0.77 dL/g and were easily dissolved in both polar, aprotic solvents and common, low-boiling-point solvents. The resulting strong and flexible polyimide films exhibited excellent thermal stability, with decomposition temperatures (at 10% weight loss) above 573 °C and glass-transition temperatures in the range of 222-251 °C. Moreover, the polymer films showed outstanding mechanical properties, with tensile strengths of 86.5-121.6 MPa, elongations at break of 9-16%, and initial moduli of 1.26-1.97 GPa. These outstanding combined features ensure that the polymers are desirable candidate materials for advanced applications.     

Polymerization,structure and thermal properties of ODPA-DMB polyimide films

A new high molecular weight polyimide based on 4,4-oxidiphthalic anhydride (ODPA) dianhydride and 2,2-dimethyl-4,4-diaminobiphenyl (DMB) diamine has been synthesizedvia a one-step polymerization method. This polyimide is soluble in phenolic solvents. Films from 7 to 30 m thick were cast from the polymer solution and show in-plane orientation on a molecular scale detected by Fourier transform infrared spectroscopy experiments. This anisotropic structure leads to anisotropic optical properties arising from two different refractive indices along the inplane and out-of-plane directions. ODPA DMB possesses high thermal and thermo-oxidative stability. The glass transition temperature has been determined to be 298 °C. Dynamic mechanical analyses show two relaxation processes appearing above room temperature: the - and the -relaxation processes. The -relaxation corresponds to the glass transition while the -relaxation is a secondary relaxation process associated with the non-cooperative subsegmental motion.Dedicated to Professor Bernhard Wunderlich on the occasion of his 65th birthdayYHK acknowledges the support from the Yonam Foundation, Korea. This work was also supported by the Center of Molecular and Microstructure of Composites (CMMC) of NSF/EPIC/Industry, SZDC gratefully acknowledges the support from his PYI Award (DMR-9157738) from the National Science Foundation.     

Synthesis and thermal degradation behaviors of hyperbranched polyphosphate

A novel epoxy-terminated hyperbranched polyphosphate (E-HBPP) was synthesized by employing an A₂ + B₃ polycondensation and characterized by FTIR, ¹H NMR and GPC. E-HBPP was used as a reactive-type flame retardant for diglycidyl ether of bisphenol-A/m-phenylene diamine (DGEBA/mPDA) system. A series of flame retardant resins were prepared and their flame retardancy was monitored by the limiting oxygen index (LOI). The results showed that the LOI value of the cured samples and the degree of expansion of the formed char after burning increased along with the E-HBPP content. Their thermal degradation behaviors were investigated by thermogravimetric analysis and in situ FTIR and showed that the phosphate group of E-HBPP first degraded to form poly(phosphoric acid)s at around 300 °C, which had a major contribution to form the compact char to protect the sample from further degradation. The dynamic mechanical thermal properties were studied by dynamic mechanical thermal analysis (DMTA) and the results showed a good miscibility between E-HBPP and DGEBA. The mechanical properties of the cured films were also investigated. Less than 20% E-HBPP addition improved both the tensile strength and elongation at break.     

Nonvolatile resistive memory devices based on ferrocene‐terminated hyperbranched polyimide derived from different dianhydrides

A series of ferrocene‐terminated hyperbranched polyimides (HBPI‐Fcs) were synthesized from a tetra‐amine, bis(4‐(3,5‐bis (4‐amino‐2‐(trifluoromethyl) phenoxy) phenoxy) phenyl) methanon, and various dianhydrides, followed by termination with (4‐amino) phenyl ferrocene. All the HBPI‐Fcs possessed good organo‐solubility and high thermal stability. The devices based on HBPI‐Fcs exhibited bipolar and nonvolatile write‐once‐read‐many times (WORM) memory performance with various threshold voltages and the same ON/OFF current ratio of 10⁴. Moreover, the devices possessed excellent bistability under a constant bias of −1.00 V during a test period of 10⁴ s. The different charge trapping ability of the electron‐accepting moiety endowed the devices with different the threshold voltages. Mechanism analysis showed that the switching behavior was dominated by the charge trapping effect and the charge transfer was well fitted with the space‐current‐limited‐current (SCLC) and ohmic model. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 505–513     

Synthesis and properties of hyperbranched polybenzimidazoles via A2 + B3 approach

Hyperbranched polybenzimidazoles (HBPBIs) were successfully synthesized by condensation polymerization of 1,3,5‐benzenetricarboxylic acid (BTA) and 3,3′‐diaminobenzidine (DAB) in polyphosphoric acid (PPA) at 190 °C. Different monomer addition manners and molar ratios resulted in different polymers, that is, simultaneous addition of BTA and DAB with the molar ratio of 1:1 (manner 1) gave carboxyl‐terminated HBPBI (HBPBI‐1), whereas the addition of BTA portion‐wise to DAB solution in PPA with the molar ratio of DAB:BTA = 2:1 (manner 2) yielded amine‐terminated HBPBI (HBPBI‐2). The free carboxyl and amino groups of HBPBI‐1 and HBPBI‐2 could further react with o‐diaminobenzene and benzoic acid, respectively, to form the chemically modified polymers. Except HBPBI‐2, all the HBPBIs showed good solubility in some organic solvents (e.g., dimethyl sulfoxide and N,N‐dimethylacetamide). Thermogravimetric analysis measurement revealed that HBPBIs except HBPBI‐1 had high thermal stability (>450 °C). HBPBI membranes with good mechanical properties were obtained by crosslinking treatment of partially chemically modified HBPBIs with terephthaldehyde (TPA) during the film cast process. The HBPBI membranes had high phosphoric acid uptake and the phosphoric acid‐doped HBPBI‐6 (40% o‐diamino groups were reacted with benzoic acid) membrane showed higher tensile strength than the acid‐doped commercial PBI despite the higher doping level of the former. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1150–1158, 2007     

Synthesis,characterisation and thermal decomposition of double sulfate

Upon evaporation at room temperature of an aqueous mixture containing Al(III) sulfate and trishydroxymethyl-ammoniummethane sulfate in a molar ratio 1:2, double sulfate as crystalline product was obtained. The stoichiometry of the obtained compound was determined by means of elemental and TG analysis. For identification, IR-spectra and X-ray powder diffraction patterns were done. It was found that the general formula of the obtained compound is Al(HOCH₂)₃CNH₃(SO₄)₂·₆H₂O. as revealed by TG, DTG and DTA analysis, the dehydration of the AL-compound takes place in one step which points out that the six water molecules are bonded in the same way. The thermal decomposition of the anhydrous compound starts at about 260°C and is very complex. This process takes place in many steps which are not well resolved. The pathway of the thermal decomposition is also supposed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis,structural characterization,and thermal properties of alkaline (earth) compounds derived from 2,4-dinitroimidazole

Eight alkaline and alkaline-earth compounds derived from 2,4-dinitroimidazole (2,4-HDNI) were synthesized and characterized by elemental analysis, FT-IR, and TG–DSC, of which K(2,4-DNI) (1), Rb(2,4-DNI)(2,4-HDNI)(H₂O)₂ (2), and Ba(2,4-DNI)₂(H₂O)₄ (3) were characterized by single-crystal X-ray diffraction analysis. All the three compounds were crystallized from water, but 1 was an anhydrate. The coordination number in 1 and 3 is 10, but in 2 is 9. The 2,4-DNI adopts either η³, η², or η¹ coordination modes depending on the metal cation. In 3, there is an inversion center located on the metal. Only in 2 does water play an important role for the construction of the structure; in 3 it is a hydrogen bonding participant. TG–DSC analyses of 1 were also performed, and non-isothermal decomposition reaction kinetics were obtained.     

Synthesis and properties of hyperbranched conjugated porphyrins

[reaction: see text] Hyperbranched conjugated porphyrin arrays were prepared by one-pot Suzuki polycondensation of AB3 and AB3 + C4 approaches.     

Bis allyl benzoxazine: Synthesis, polymerisation and polymer properties

A bis benzoxazine monomer with allyl groups viz: 2,2′-bis (8-allyl-3-phenyl-3,4-dihydro-2H-1,3-benzoxazinyl) propane (Bz-allyl) was synthesized via a solventless method from 2,2′diallyl bisphenol-A, paraformaldehyde and aniline. The chemical structure of Bz-allyl was confirmed by FTIR, ¹H NMR and ¹³C NMR analyses. The monomer manifested a two-stage thermal polymerisation pattern. The first stage was attributed to the polymerisation of the allyl groups and the second to the ring - opening polymerisation of benzoxazine moiety. The polymerisation profile was investigated with DSC, FT-IR, TGA and pyrolysis-GC techniques. A polymerisation mechanism involving the electrophilic addition of the propagating iminium cation on the aniline ring in lieu of the activated sites of bisphenol-A, (which are blocked by allyl and alkyl substituents) was proposed. Additional cross-linking was provided by thermal addition polymerization of allyl groups. As a result of altered cross-linking via the aniline moiety and the additional cross-linking via allyl groups, the cured polymer exhibited a T_g of ca. 300 °C and high crosslink density. The thermal stability of this polymer was also substantially higher vis-à-vis that of the bisphenol-A based polybenzoxazine. The work focuses on the manipulation of benzoxazine monomer structure to alter the ring-opening polymerisation mechanism and cross-linking to derive polybenzoxazine with improved properties.     

Synthesis,spectral, and thermal properties,and crystal structure of cobalt (III) complex derived from Imazameth

A novel metal–organic coordination compound [Co(Imazameth)₃]·0.5DMF·4H₂O (where Imazameth = (±)-2-(4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H- imidazol-2-yl)-5-methyl-3-pyridinecarboxylic acid; DMF = N,N-dimethylformamide) has been prepared and characterized by spectral method (IR), elemental analysis, thermal gravimetric analysis (TGA), fluorescence properties, and single crystal X-ray diffraction techniques. It crystallizes in the trigonal system, space group R-3 and the asymmetric unit contains four water molecules. The four lattice water molecules and their symmetric equivalent form a slight distorted cubical water cluster through hydrogen bonds. The O···O bonds of the water cluster are in the range of (2.80(7)–2.99(2) Å), and O···O···O angles are in the range of (82.54°–101.38°). In the cubical water clusters, the six O(5) atoms of each cube are connected to six O(1) atoms of the six molecules (O(1)···O(5) = 2.77(1) Å) by hydrogen bonding, respectively. The Co atom is six-coordinated by six N atoms in distorted octahedron coordination geometry. Intramolecular N–H···O and intermolecular O–H···O hydrogen bonds result in the formation of a supermolecular crystal, in which they seem to be effective in the stabilization of the structure. The complex displays strong fluorescence property and good thermal stability.