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Polymeric coating materials (PCMs) are promising candidates for developing next-generation flexible displays. However, PCMs are frequently subjected to external stimuli, making them highly susceptible to repeated damage. Therefore, in this study, a highly self-healing PCM based on a charge transfer complex (CTC) was developed, and its thermal, self-healing, and mechanical properties were examined. The self-healing material demonstrated improved thermal stability, fast self-healing kinetics (1 min), and a high self-healing efficiency (98.1%) via CTC-induced multiple interactions between the polymeric chains. In addition, it eliminated the trade-off between the mechanical strength and self-healing capability that is experienced by typical self-healing materials. The developed PCM achieved excellent self-healing and superior bulk (in-plane) and surface (out-of-plane) mechanical strengths compared to those of conventional engineering plastics such as polyether ether ketone (PEEK), polysulfone (PSU), and polyethersulfone (PES). These remarkable properties are attributed to the unique intermolecular structure resulting from strong CTC interactions. A mechanism for the improved self-healing and mechanical properties was also proposed by comparing the CTC-based self-healing PCMs with a non-CTC-based PCM.

Here, highly stretchable and transparent UV curable poly(urethane-acry-late) elastomer has been synthesized by reacting urethane acrylate oligomer and two reactive diluents monomers. The synthesized elastomers can be stretched up to 600% and have high transparency of over 90% transmittance. The synthesized elastomers have been applied to several applications. Simple 3D model was printed with a 3D printer on the market. Stretchable ionic conductors were fabricated by a facile method of adding salt with ionic conductivity. Similarly, the resin with β-cyclodextrin, a cage-structured molecule, was cured and foam was generated simultaneously under the UV radiation. This research paves a new way for further development in applications of UV curable transparent elastomer and 3D printable elastomeric material.

Polyimides, a widely used engineering plastic, require use of large amounts of toxic and hazardous organic solvents which threaten our daily lives, calling for new and easy synthetic methods for sustainable environmentally friendly development. In this paper, highly soluble fluorinated polyimides based on 4,4′-(hexafluoroisopropylidene) diphthalic anhydride were synthesized via hydrothermal process without using any toxic organic solvents and the advantages of the newly demonstrated synthetic methods are shown by comparative analysis performed with the two conventional synthetic methods using organic solvent: thermal and chemical imidization. Lower temperature is required (~200 °C) compared to thermal imidization and functional groups for high fusibility formed more easily compared to chemical imidization. According to the comparative analysis, hydrothermally synthesized PIs showed excellent solubility and maintained high thermal stability (&gt, 500 °C) and glass transition temperature (&gt, 300 °C) compared to conventional PI. The hydrothermally synthesized polyimide is much more convenient to store and manage than other form of polyimide which is much more stable when it is exposed to humidity as it is a powder form. The hydrothermal synthetic method is verified to be a “Green” and facile method for sustainable PI synthesis.

The development of tannic‐acid‐based textile materials is a good candidate that enables both flame retardancy and antibacterial properties. When nanocarbon materials are used together, it is possible to not only realize complex functions but also increase physical properties, thereby expanding the potential range of application of the materials.

A transparent poly(amide-imide) (PAI) was synthesized with good thermal and optical properties and after that silica nano particles were introduced and removed for nano porous polymer matrix. The successful synthesis of PAI with nano scale porous structure was confirmed with FT-IR and FE-SEM measurement. The effects of free volume of polymer on thermal properties were measured with TGA and DSC. This physically modified polymer matrix showed increased thermal degradation and glass transition temperature over 250 °C. In the case of optical properties, UV-Vis and yellow index were measured and PAI with nano porous structure showed transparent colorless properties with light transmittance in the range of 80-40% and yellow index 2.1-1.1. The results also showed low dielectric constant in the range of 3.2-2.5 and contact angles that of 70-73°.

New diamines for high-performance poly(ester imide)s (PEsIs) containing dimethyl groups at the ortho-position of amino groups and ester derivatives have been developed to improve optical transparency and glass transition temperature (Tg) while maintaining a low coefficient of thermal expansion (CTE). Four kinds of PEsIs derived from bis(4-amino-3,5-dimethylphenyl) terephthalate (BADMT) and aromatic dianhydrides such as 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA), 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), 4,4’-oxydiphthalic anhydride (ODPA), and 4,4'-(hexafluoroisopropylidene)diphthalic (6FDA) were synthesized via a two-step polycondensation. All PEsIs exhibited outstanding properties, such as light color, a good transmittance of >90% at 550 nm, high Tg above 289 °C and 5% weight loss temperature (483–511 °C), and low CTE (11–68 ppm/°C). The effect of the substituent on molecular packing and properties, including optical and thermomechanical properties for the resulting PEsIs were examined in detail. The temperature-dependent CTE of the PEsIs was determined using molecular dynamics (MD) simulation. The molecular orbital (MO) calculation models support the discussions on the electronic substituent effect of the PEsI main chains. Our molecular architecture and systematic property studies with MD and MO promote a better understanding of the polyimides.

We report an efficient route for ferroelectric polar β phase generation in poly(vinylidene fluoride) (PVDF) through incorporation of amine functionalized, porous silica (MCM-41 and fumed silica) based nanofillers. These porous highly functionalized surfaces exhibit the efficient secondary interaction with polymer chain via hydrogen bonding. Structural analysis through FTIR, XRD, and TEM confirm high degree of ferroelectric polar β phase generation of PVDF through incorporation of amino modified porous silica nanofillers. Optimized loading (5 wt %) of amine functionalized, porous silica in PVDF matrix enhances relative intensity of β phase up to 75%. Disappearance of spherulite structure of PVDF with amino modified porous silica nanofillers, as confirmed through POM, TEM, SEM and AFM studies also supports the above conclusion. The P-E hysteresis loop at sweep voltage of ±50 V of a thin PVDF-amino modified porous nanofiller film shows excellent ferroelectric property with nearly saturated high remnant polarization 2.8 µC.cm−2 owing to its large proportion of β PVDF, whereas, a nonpolar pure PVDF thin film shows unsaturated hysteresis loop with 0.6 µC.cm−2 remnant polarization. PVDF films with the nanofillers exhibit strong adhesive strength over different metallic substrates making them have edge over PVDF in various thin film applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2401–2411

Supercritical methanol is a popular fluid as a supercritical medium for decrosslinking reaction of crosslinked polyethylene. However, due to its toxicity, a safe alternative medium is much to be desired. In this work, various sub- and supercritical fluids with different polarity characters were investigated to find a safe alternative medium for continuous decrosslinking of silane-crosslinked polyethylene (S-XLPE). Like methanol, all examined fluids, including ethanol, propanol, and water, exhibited first-order reaction kinetics regarding the gel content in the continuous decrosslinking process. The reaction rate constant values were observed as 2.806, 2.569, 2.383, and 2.130 min −1 in supercritical methanol, supercritical ethanol, supercritical 2-propanol, and subcritical water at 380 °C, respectively. As a non-toxic fluid with reaction kinetics very comparable to that of methanol, ethanol was found to be the best alternative medium for the continuous decrosslinking reaction of S-XLPE.

For the first time, a kinetic study on the supercritical decrosslinking reaction of silane-crosslinked polyethylene (S-XLPE) in a continuous process was conducted. The decrosslinking reaction in a continuous process was corresponding to the first-order reaction model in which the reaction rate was linearly proportional to the gel content. The residual gel content exponentially decreased with reaction time. Reaction constant was observed exponentially related to the reaction temperature. The continuous decrosslinking reaction revealed kinetic constants of 1.355 ± 0.103, 2.715 ± 0.177, and 4.348 ± 0.218 min −1 at 360, 380 and 390 °C, respectively and activation energy of 132.36 kJ mol −1 .

A polyimide aerogel (PIA) was used to synthesize low-dielectric-constant polyimide composite films. Unlike silica aerogel (SIA) composites, the PIA films were synthesized using polyimide. The resulting films maintained the original thermal and chemical properties of polyimide, which contribute to their homogeneity. The dielectric constant of the aerogel composite film was decreased to ~2.4, a value similar to that of a SIA composite film. The increase in dielectric constant as a result of water adsorption exhibited by SIA films was counteracted by the hydrophobicity of the polyimide in the PIA film. The PIA composite film exhibited a 3% water uptake, compared with a 29% water uptake in the SIA film, indicating that the polyimide film is the preferred choice in wet conditions. The presence of a uniformly dispersed aerogel, a 1% thermal decomposition temperature of 589 °C and a glass transition temperature of 298 °C for the PIA composite film were confirmed by field emission scanning electron microscopy, thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) analysis, respectively. The TGA and DSC results demonstrated that the excellent thermal properties of polyimide were maintained in the PIA composite film. Polyimide aerogel (PIA) was used to synthesize low-dielectric-constant polyimide composite films. Unlike silica aerogel composites, the polyimide aerogel composite films were synthesized solely based on polyimide. The films maintained the original thermal and chemical properties of polyimide contributing to their homogeneity. The presence of uniformly dispersed aerogel, the high-thermal decomposition and glass transition temperature of the PI–PIA sample films were confirmed by field emission scanning electron microscope, TGA and DSC analysis. The FE-SEM image of the PI–PIA film samples indicates that the PIA particles were well-dispersed in the film and retained their spherical shape.

In this study, poly(amide-imide)s are synthesized for electronic materials by adding amide groups into polyimide. As it is expected, poly(amide-imide) shows an amorphous structure with a lower glass transition temperature and residual stress than the neat polyimide due to the high steric hindrance of the amide group. Also, the modification to the polyimide structure leads to higher transmittance and enhances colorless properties. Consequently, successful synthesis of poly(amide-imide)s is demonstrated which has wide applicability in the electronic industries due to their low glass transition temperature. It is expected that semiconductor and integrated circuit products can be manufactured utilizing poly(amide-imide)s with high reliability and a low chance of cracking due to their lower residual stress. Furthermore, it envisioned that the improved optical properties of poly(amide-imide) materials will allow for their applications in transparent displays and coating products.

Graphene nanoparticles coated with tannic acid were synthesized as non-halogen flame retardants; further, these nanoparticles were electrospun with polyurethane to produce multifunctional composite nanofibers. The composite nanofibers showed improved flame retardant, antimicrobial, and mechanical properties with increasing amounts of bio-based, non-halogen flame retardant. For instance, at 5 wt% of flame retardant, the peak heat release rate was reduced from 340.75 to 235.23 W/g along with 500% and 135% improvement in the antimicrobial activity and Young's modulus, respectively, compared to neat polyurethane fibers. These multifunctional composite nanofibers have potential applications in various fields, such as automobile, construction, and biomedical device.

To cope with the demand for cleaner alternative energy, polymer electrolyte membrane fuel cells (PEMFCs) have received significant research attention owing to their high-power density, high fuel efficiency, and low polluting by-product. However, the water requirement of these cells has necessitated research on systems that do not require water and/or use other mediums with higher boiling points. In this work, a highly porous meta-polybenzimidazole (m-PBI) membrane was fabricated through the non-solvent induced phase inversion technique and thermal cross-linking for high-temperature PEMFC (HT-PEMFC) applications. Standard non-thermally treated porous membranes are susceptible to phosphoric acid (PA) even at low concentrations and are unsuitable as polymer electrolyte membranes (PEMs). With the porous structure of m-PBI membranes, higher PA uptake and minimal swelling, which is controlled via cross-linking, was achieved. In addition, the membranes exhibited partial asymmetrical morphology and are directly applicable to fuel cell systems without any further modifications. Membranes with insufficient cross-linking resulted in an unstable performance in HT-PEMFC environments. By optimizing thermal treatment, a high-performance membrane with limited swelling and improved proton conductivity was achieved. Finally, the m-PBI membrane exhibited enhanced acid retention, proton conductivity, and fuel cell performance.

Light-colored polyimide hybrids with a quaternary alkylammonium modified montmorillonite, Cloisite® 20A (C20A) were successfully synthesized via a solution intercalation method. The structural and morphological features of the PI/C20A hybrids were characterized by Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD), field emission scanning electron microscopy (FE-SEM), and spherical aberration correction scanning transmission electron microscope (STEM). The dimensional stabilities were strongly dependent upon the chemical and morphological structures which were influenced by the Cloisite® 20A loading content. A critical Cloisite® 20A concentration was obtained for the evolution of both the structural and physical properties of the PI/C20A hybrids. The dynamic stress behaviors were investigated in situ by using the wafer bending method during thermal imidization of the softbaked PI/C20A hybrid precursor and thermally cured hybrid films using a thin film stress analyzer. The PI/C20A hybrid films exhibited stability at 510 °C, high glass transition and relatively low coefficient of thermal expansion, and an improved solvent resistance capacity. Open image in new window

The effects of norbornene (NE) crosslinking and diamine bridge linkages (ether, sulfone, and trifluoromethyl) on polyimide films were investigated. The purpose of this study was to study the behavior of the NE endcapped polyimide with different diamine bridge linkage structure at elevated temperatures on residual stress and modulus change. 5-Norbornene-2,3-dicarboxylic acid was introduced as the end-capping agent in order to increase the ratio of crosslinking in the structure through reverse Diels-Alder reaction. Wide angle X-ray diffraction (WAXD) was measured to study the relation of d-spacing and structure change of the bridge linkage of polymers through NE crosslinking. Coefficient of thermal expansion (CTE) and residual stress were measured to confirm the loaded stress between the substrate and polymer film through a thin film stress analyzer (TFSA). Storage (e′) and loss modulus (e″) were studied at elevated temperatures to study the relation of bridge linkage mobility of the polyimide at elevated temperature.

In this work, Al–Si was synthesized via a sol–gel process and introduced in poly 2,2′-m-(phenylene)-5,5′-bibenzimidazole (PBI). As a result, a series of five Al–Si/PBI composite (ASPBI) membranes (0, 3, 6, 9, and 12 wt%) were developed and characterized for application in high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). The chemical and morphological structure of ASPBI membranes were analyzed by Fourier transform infrared spectroscopy, X-ray diffractometer, and scanning electron microscopy. According to the doping level test and thermogravimetric analysis, as the concentration of Al–Si increased, the doping level increased up to 475% due to the affinity and interaction between Al and phosphoric acid (PA). Moreover, the proton conductivity, current density at 0.6 V, and maximum power density of ASPBI membranes increased up to 0.31 S cm−1, 0.320 A cm−2, and 0.370 W cm−2, respectively, because the increased concentration of Al–Si allows the membranes to hold more PA. Alternatively, as the amount of Al–Si increased, the tensile strength of PA-doped and -undoped membranes decreased. This was caused by both excess PA and aggregation, which can cause serious degradation of the membrane and induce cracks. Furthermore, the PA-doped and -undoped ASPBI12 had the lowest tensile strength of 11.6 and 77.2 MPa. The improved proton conductivity and single cell performance of ASPBI membranes implies that these membranes are possible candidates for HT-PEMFC applications. However, further studies seeking to enhance the compatibility between PBI and Al–Si and optimize the amount of filler should be performed. POLYM. COMPOS., 38:87–95, 2017. © 2015 Society of Plastics Engineers

A novel method for synthesizing a microsponge polyimide (PI) film with excellent thermal stability, chemical resistance, and heat insulation performance was developed. The synthesized microsponge PI film has open cells with sizes between 1 and 10 μm and a porosity of 76%. Furthermore, the film contains several layers overlapping in multiple grid structures, which complicates the heat transfer paths. Thus, the heat transfer coefficient of the microsponge PI film is 67% less than that of existing polyimide film (0.054 vs. 0.16 W/m·K). This reduced heat transfer coefficient results in excellent heat insulation performance of the microsponge PI film. The thermal decomposition (pyrolysis) of the microsponge PI starts at 498 °C and its glass transition temperature is 317 °C, which indicates excellent thermal stability. However, its Young's modulus, an indicator of mechanical strength, is nearly 74% less than that of conventional PI film (26 vs. 100.2 MPa).

Cross-linked polyimides (PIs) were synthesized by reacting 4,4'-(hexafluoroisopropylidene)-diphthalic anhydride (6FDA) and 2,2'-bis(trifluoromethyl)benzidine (TFDB) with various ratios of the cross-linkable, end-capping agent cis-1,2,3,6-tetrahydrophthalic anhydride (CDBA) via ring-opening metathesis polymerization. Residual stress behaviors were investigated in-situ during thermal imidization of the cross-linked PI precursors using a thin film stress analyzer (TFSA) by wafer bending method. The thermal properties were investigated via differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and thermogravimetric analysis (TGA). The optical properties were measured by ultraviolet-visible spectrophotometer (UV-vis) and spectrophotometry. All properties were interpreted with respect to their morphology of cross-linked networks. With increasing the amounts of the end-capping agent, the residual stress decreased from 27.9 to -1.3 MPa, exhibited ultra-low stress and high thermal properties. The minimized residual stress and enhanced thermal properties of the cross-linked PI makes them potential candidates for versatile high-density multi-layer structure applications.

Tetrapod zinc oxide whiskers (TZnO-Ws) were successfully prepared by a thermal oxidation method and confirmed using scanning electron microscopy (SEM) and wide angle X-ray diffraction (WAXD). A series of polyimide (PI)/TZnO-W composite films containing the as-prepared various TZnO-W contents were prepared and their physical properties were investigated to understand their potential use in flexible displays. The morphology, physical, and moisture barrier properties of the PI/TZnO-W composite films were interpreted as a function of the TZnO-W content. The PI/TZnO-W composite films exhibited an optical transparency greater than 80% at 550 nm (≤0.5 wt% TZnO-W content), a low coefficient of thermal expansion (CTE), and enhanced glass transition temperature. However, the thermal decomposition temperature decreased as the TZnO-W content increased. Although the mechanical strength increased up to 0.3 wt% TZnO-W content, it decreased due to poor interfacial interaction with high TZnO-W loading. The water vapor transmission rate (WVTR) and water uptake of the composite films, which were strongly dependent upon their morphological and chemical structure, varied from 508.3 to 325.2 g/m2/day and 3.7 to 1.3 wt%, respectively, greatly decreased as the TZnO-W content increased. The water resistance capacity of PI was greatly enhanced and moisture diffusion in the pure PI was retarded by incorporating the TZnO-W.

Polyimide is a major polymer material in the electronics industry, and we conducted a study to cure polyimide at low temperatures in order to improve its thermal and mechanical properties. In this study, polyimide/clay nanocomposites were prepared by the reaction of 4,4’-(hexafluoro isopropylidene) diphthalic anhydride (6FDA) and 4,4’-oxydianiline (ODA) with the addition of 1,4-dizabicyclo[2.2.2]octane (DABCO) as a low-temperature catalyst and nanoclay (Cloisite 20A). The synthesis of polyimide at low temperatures and the dispersion of a nanoclay in the polymer matrix was confirmed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), respectively. Thermal stabilities of the nanocomposites were confirmed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The mechanical properties were measured by an universal testing machine. We demonstrated that when polyimide was cured at low temperatures and short curing times, it was possible to improve the thermal and mechanical properties via the addition of a catalyst and inorganic material. Polyimide with DABCO and 0.25 wt% nanoclay showed a 5 °C higher degradation temperature, 560.88 °C; a 6 °C higher glass transition temperature, 293.62 °C; and a 20 MPa greater tensile strength, 136.94 MPa. Therefore, the polyimide curing process was demonstrated to be successful at low temperatures.

A series of polyimide (PI) was prepared by reacting 4,4'-(hexafluoroisopropylidene)-diphthalic anhydride (6FDA) as the anhydride and bis(3-aminophenyl) sulfone (APS), bis(4-(3-aminophenoxy)-phenyl) sulfone (BAPS), 2,2- bis(4-aminophenyl)-hexafluoropropane (6FPD), 2,2-bis(4-(4-aminophenoxy)-phenyl)hexafluoropropane (6FBAPP), 2,2'- bis(trifluoromethyl)benzidine (TFDB), or 1,4-phenylenediamine (PDA) as the diamine. Residual stress behaviors were detected in-situ during thermal imidization of the polyimide precursors using a thin film stress analyzer (TFSA), and inter- preted with respect to their morphology. According to the molecular orientation and packing order, the residual stress var- ied from 23.1 to 12.5 MPa, decreased with increasing chain rigidity. The thermal properties of the PI films were investigated using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and thermomechanical analysis (TMA). Their optical properties were measured by ultraviolet-visible spectrophotometer (UV-vis), and spec- trophotometry. The properties of PI films were found to be strongly dependent upon the morphological structure. How- ever, trade-offs between residual stress and optical properties were identified.

A series of polyimide (PI) nanocomposite films with various surface-modified colloidal calcium carbonate (SCaCO3) contents were prepared and their physical properties were investigated to understand their possible use as polymer substrates. The morphology, thermal stability, residual stress behavior, moisture barrier and optical properties of nanocomposite films were investigated as a function of the SCaCO3 content and were found to be strongly dependent upon the chemical and morphological structures. With the addition of up to 0.5 wt% SCaCO3 in the PI matrix, resultant nanocomposite films exhibit not only enhanced thermal properties, but also minimized residual stress and excellent optical properties, simultaneously. With increasing SCaCO3 content, the water vapor transmission rate (WVTR) is greatly decreased from 630.76 to 484.22 g/m2/day. The residual stress was in the range of 26.0 to 12.1 MPa and is highly dependent on both temperature variation and SCaCO3 content. Although the residual stress becomes lower at 0.5 wt% SCaCO3 content, it increases at relatively high SCaCO3 loadings due to inadequate dispersion of the SCaCO3 and low interfacial interactions between the polymer and filler surfaces. Therefore, further studies are needed to maximize the performance of nanocomposite films by enhancing the compatibility of the polymer matrix and fillers.

In the study described here, novel, polyimide (PI)-based spherical aerogelmicroparticles are fabricated. The aerogel microparticles proposed in this study have an advantage over film-shaped aerogels because the microparticles can be easily used for thermal insulation, drug release, and catalyst support. By using only a PI polymer as the raw material for the proposed PI aerogel microparticles, the problems associated with reinforcing conventional silica aerogels, such as inferior thermal resistance or incorporation with silica aerogel, are circumvented. The porosity of PI aerogel microparticles was determined to be 80% and specific surface area was determined as 103 m2 g−1. The pore sizes measured using mercury intrusion porosimetry are between 4 and 100 nm, with a representative pore size of 15 nm.

A series of poly(vinyl alcohol)/sodium montmorillonite (PVA/NaMMT) nanocomposite films were prepared via a solution method, and their water sorption and water-resistant properties were investigated as a function of clay content. The water sorption and water resistance properties were strongly dependent on the chemical structure and film morphology originating from the NaMMT content. The water diffusion coefficient and water uptake of the PVA/NaMMT nanocomposite films were obtained by best fits to a Fickian diffusion model. The diffusion coefficient and water uptake in the PVA/NaMMT nanocomposite films varied between 8.16 × 10−10 and 3.60 × 10−10 cm2 s−1 and 35.6 and 29.9 wt%, respectively. Both the diffusion coefficient and water uptake decreased as the content of NaMMT in pure PVA was increased. Additionally, the water resistance pressure (mm) of the PVA/NaMMT nanocomposite films increased with increasing NaMMT content. Contact angle analyses showed that the chemical affinity to water and the surface energy of the nanocomposite films decreased with increasing NaMMT content. Furthermore, the well-dispersed and exfoliated structure in the nanocomposite films not only induced an increased tortuous path for water molecules to pass through, but also increased the molecular order. However, to enhance the water sorption properties and water resistance of hydrophilic PVA, further studies to increase the dispersion of clay particles and ensure desired morphological qualities such as crystallinity and molecular packing order in the PVA/clay nanocomposite films are required. POLYM. COMPOS., 36:660–667, 2015. © 2014 Society of Plastics Engineers

We investigated the decreased water diffusivity depending on the content and size of carbon black (CB) added to polyimide (PI) in order to synthesize composite films (PI-CB). CBs with different diameters were used: N110 (CB1, 11–19 nm), N326 (CB2, 26–30 nm) and N660 (CB3, 49–60 nm). The water diffusion coefficient of PI-CB decreased with increasing CB content from 2.67·10−9 for pure PI films to 0.22·10−9 cm2/s for PI-CB films containing 40 wt% CB1. Moreover, the decrease in water diffusivity with increasing CB content exhibited a linear relationship. The water diffusivity of PI-CB increased with the increasing size of CB at the same CB content. The water uptake of PI-CB had a linear relationship depending on the CB content, similar to water diffusivity; the water uptake of composite films decreased by 73% (from 3.67% to 0.98%) for PI-CB1 (40 wt%) films as compared to PI films. In addition, the water uptake varied not only with the CB content, but also by the size of the CB surface area. Open image in new window

A novel high-performance material, carbon black (CB) polyimide (PI), was obtained by the chemical synthesis of CB (carbon black N326) with PI. Following its synthesis, several analyses were carried out to investigate the thermal and mechanical properties of the newly synthesized CB-PI. The thermal decomposition temperature of CB-PI compared to PI increased by 76°C from 508 to 584°C. The glass transition temperature of CB-PI as evaluated by differential scanning calorimetry increased by 204°C from 379 to 583°C compared to that of PI. Moreover, the mechanical strength of CB-PI increased by 16% compared to that of PI. In addition, the analyses confirm that CB and PI in the synthesized CB-PI were chemically crosslinked, which was shown to be responsible for the superior thermal and mechanical properties of the CB-PI. POLYM. COMPOS., 35:2214–2220, 2014. © 2014 Society of Plastics Engineers

Hollow polyimide (PI) microspheres are prepared through an electrospraying process, followed by surface imidization. The precipitation of droplets at the interface between two immiscible liquids provides a scaffold for the formation of a thin layer while an in situ imidization reaction prevents the irreversible deformation of the hollow shell. This strategy easily yields robust hollow structures of PI microspheres. The electrospray process permitts the sizes of the hollow PI microspheres to be controlled through adjustments to the flow rate and concentration of the poly(amic acid) (PAA) solution. The electrospraying approach described here may be the most facile means yet reported for obtaining size-controlled hollow PI particles without the need for additives or surfactants.

A series of ethyl-vinyl alcohol (EVOH) nanocomposite films with exfoliated graphite nanosheets (EGn) were prepared via a solution blending method and their physical and moisture barrier properties were investigated as a function of the EGn content. The physical properties were strongly dependent upon the chemical and morphological structures originating from the differences in EGn composition. The nanocomposite films showed no strong interactions between the polymer and EGn filler, and this resulted in poor dispersion in relatively high content EVOH/EGn nanocomposites. With increasing content of EGn particles, the water vapor transmission rate varied in the range of 1.29 to 3.14 cc/m2/day and the water uptake greatly decreased from 9.1 to 3.4 wt%. The water resistance capacity of EVOH was greatly enhanced and moisture diffusion in the pure EVOH film was retarded by introducing the EGn. However, thermal stabilities were not improved by incorporating EGn due to the poor interaction between EVOH polymer chains and the EGn surface. Open image in new window

Relatively high aspect ratio exfoliated graphite (EFG) particles with an average size of 7.4 mu m and a nanometer sized thickness of 30-50 nm were successfully prepared by thermal treatment at 1050 degrees C and subsequent ultrasonication for application as a filler to improve the physical properties of eco-friendly poly(propylene carbonate) (PPC). A series of poly(propylenecarbonate)/exfoliated graphite (PPC/EFG) nanocomposite films with different EFG contents were prepared via a solution blending method. The physical properties were strongly dependent upon the chemical and morphological structures originating from the differences in EFG composition. The morphological structures, thermal properties, mechanical properties and barrier properties of the nanocomposite films were investigated as a function of the EFG content. While all of the PPC/EFG nanocomposite films exhibited good dispersion of EFG to some extent, Fourier transform infrared and SEM results revealed that solution blending did not lead to strong interactions between PPC and EFG. As a result, poor dispersion occurred in composite films with a high EFG content. By loading EFG particles, the oxygen permeabilities, moisture permeabilities and water uptake at equilibrium decreased as the EFG content increased. Compared with pure PPC, PPC/EFG nanocomposite films have enhanced molecular ordering. Specifically, the 2% PPC/EFG composite film shows greater molecular ordering than the other composite films, which results in the highest mechanical strength. In future work, the compatibility and dispersion of the PPC matrix polymer and EFG filler particles should be increased by modifying the EFG surface or introducing additives

A novel hyper-branched polybenzimidazole (HB-PBI) has been synthesized and efficiently utilized as a conducting polymer for the fabrication of an efficient high temperature fuel cell. The developed fuel cell showed outstanding proton conductivity (0.168 Scm(-1) at 150 A degrees C) along with excellent single cell performance, displaying a maximum power density of 0.346 Wcm(-2). The HB-PBI has been synthesized by polymerization of bibenzimidazole diterephthalic acid (BBIDTA) and 3,3'-diaminobenzene in the presence of poly phosphoric acid while the BBIDTA was synthesized by treating trimellitic anhydride with 3,3'-diaminobenzene. Both HB-PBI and BBIDTA were structurally characterized by nuclear magnetic resonance (H-1 and C-13 NMR). HB-PBI showed high thermal stability and mechanical properties, findings that were corroborated by thermogravimetric analysis and use of a universal testing machine. Additionally, proton conduction and the thermal and mechanical properties of HB-PBI were compared with polybenzene imidazole (m-PBI), and found that HB-PBI has higher proton conducting, thermal and mechanical properties.

Tetrapod zinc oxide whiskers (TZnO-Ws) were successfully synthesized via a thermal oxidation method and confirmed using Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. A series of poly(urethane acrylate) (PUA)/TZnO-W composite films with various TZnO-W contents were prepared via a UV curing method and their physical properties were investigated to understand their possible use as packaging materials. The morphological, thermal, mechanical, antibacterial and barrier properties of the PUA/TZnO-W composite films were interpreted as a function of TZnO-W content. The thermal stability, barrier properties and antibacterial properties of the composite films, which were strongly dependent upon their chemical and morphological structure, were enhanced as the TZnO-W content increased. The oxygen transmission rate and water vapor transmission rate decreased from 614 to 161 cm3 m−2 per day and 28.70 to 28.16 g m−2 per day, respectively. However, the mechanical strength of the films decreased due to the low interfacial interaction and poor dispersion with high TZnO-W loading. The enhanced barrier properties and good antibacterial properties of the PUA/TZnO-W composite films indicate that these materials are potentially suitable for many packaging applications. However, further studies are needed to increase the compatibility of polymer matrix and filler. © 2012 Society of Chemical Industry

The thermal cationic latent initiators, N-benzyl-3-methylimidazolium hexafluoroantimonate (BMH1) and N-butyl-3-methylimidazolium hexafluoroantimonate (BMH2) were synthesized and applied to the thermal cationic polymerization of diglycidyl ether of bisphenol A (DGEBA). The performance of BMH1 and BMH2 was examined by differential scanning calorimetry (DSC), which showed good thermal latent properties and excelled epoxy resin curing behavior. The morphology, thermal, mechanical, and water sorption properties of DGEBA resin cured by 1 wt% of BMH1 and BMH2 were measured by X-ray diffraction (XRD), scaming electron microscopy (SEM), thermogravimetric analysis (TGA), nanoindentation, and thin film diffusion analysis. The cured DGEBA/BMH1 system showed relatively higher thermal stability than the DGEBA/BMH2 system. The diffusion coefficient and water uptake were 14.2×10−9 cm2/s and 1.15 wt% for the DGEBA/BMH1 system and 11.5×10−9 cm2/s and 1.07 wt% for the DGEBA/BMH2 system, respectively. Therefore, DGEBA/BMH2 showed higher resistance to water sorption than DGEBA/BMH1. On the other hand, hardness and elastic modulus of DGEBA/BMH2 were higher than those of DGEBA/BMH1. This can be attributed to the difference in the end group of initiators as well as the degree of crosslinking in the cured resin network. Open image in new window

Organic-inorganic hybrid membranes (HM1-HM4) were synthesized by incorporating 3 wt% (HM1), 5 wt% (HM2), 10 wt% (HM3), and 20 wt% (HM4) of silica precursors into UV-curable polyurethane acrylate (PU) matrix using sol-gel technique. PU, which was prepared by reacting polycaprolactone triol (PCLT) and isophorone diisocyanate (IPDI), was used as the starting organic polymer whereas tetraethoxysilane (TEOS) was used as a precursor for the development of the inorganic phase. The completion of the polymerization reaction of PU and the synthesis of hybrid membranes were confirmed by Fourier transform infrared spectroscopy (FTIR) whereas the morphology was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The thermal, mechanical, and anti-water sorption properties of the hybrid membranes were examined by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), nanoindentator and thin film diffusion analysis, which revealed that HM2 has the highest thermal, mechanical, and anti-water sorption properties. TGA demonstrated that the thermal decomposition temperature (T d10%) of HM2 increased significantly, being 30 °C higher than that of pure PU, whereas DSC indicated that the introduction of 5 wt% of TEOS increased the glass transition temperature from 93.8 to 103 °C. Accordingly, the mechanical and water sorption properties were also enhanced greatly as evidenced by nanoindentation analysis and anti-water sorption data, in which HM2 shows the highest elastic modulus (8.354 GPa), hardness (0.262 GPa), and lowest water sorption capacity. These thermal, mechanical, and anti-water sorption improvements are important for the practical process and applications of PU.

Organic-inorganic hybrids (H1-H5) based on environmentally friendly and biodegradable polymer, poly (propylene carbonate) (PPC) and tetraethoxysilane (TEOS) were synthesized using the sol-gel technique. The synthesized hybrids were characterized structurally and morphologically by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). H1-H5 were examined in term of detailed thermal, mechanical, and anti-water sorption properties using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) nanoindentation, and thin film diffusion analysis, which revealed that H4 has the highest thermal, mechanical, and anti-water sorption properties. H4 greatly increased the thermal decomposition temperature (T d10%) and glass transition temperature, which are 45 and 11 °C higher than that of pure PPC. Accordingly, H4 showed a high storage modulus (2.54 × 109 Pa), elastic modulus (2.601 ± 0.110 GPa), hardness (0.175 ± 0.013 GPa), and lowest water absorption. This improvement in the thermal, mechanical, and anti-water absorption properties of PPC shows that PPC can be used as a packaging and bio-material.

A series of polypropylene carbonate (PPC)/ZnO nanocomposite films with different ZnO contents were prepared via a solution blending method. The morphological structures, thermal properties, oxygen permeability, water sorption, and antibacterial properties of the films were investigated as a function of ZnO concentration. While all of the composite films with less than 5 wt % ZnO exhibited good dispersion of ZnO in the PPC matrix, FTIR and SEM results revealed that solution blending did not lead to a strong interaction between PPC and unmodified ZnO. As such, poor dispersion was induced in the composite films with a high ZnO content. By incorporating inorganic ZnO filler nanoparticles, the diffusion coefficient, water uptake in equilibrium, and oxygen permeability decreased as the content of ZnO increased. The PPC/ZnO nanocomposite films also displayed a good inhibitory effect on the growth of bacteria in the antimicrobial analysis. The enhancement in the physical properties achieved by incorporating ZnO is advantageous in packaging applications, where antimicrobial and environmental-friendly properties, as well as good water and oxygen barrier characteristics are required. Furthermore, UV light below ∼ 350 nm can be efficiently absorbed by incorporating ZnO nanoparticles into a PPC matrix. ZnO nanoparticles can also improve the weatherability of a PPC film. In future research, the compatibility and dispersion of the PPC matrix polymer and the inorganic ZnO filler nanoparticles should be increased. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.

Page 1115, the Acknowledgments should be corrected as follows: This work was supported by the KIST Institutional Program (Project No. 2E26600-16-041) and National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2017R1D1A1B03033332).

Four different structure polyimide thin films based on 1,4-phenylene diamine (PDA) and 4,4′-oxydianiline (ODA) were synthesized by using two different dianhydrides, pyromellitic dianhydride (PMDA) and 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA), and their residual stress behavior and mechanical properties were investigated by using a thin film stress analyzer and nanoindentation method. The residual stress behavior and mechanical properties were correlated to the morphological structure in polyimide films. The morphological structure of polyimide thin films was characterized by X-ray diffraction patterns and refractive indices. The residual stress was in the range of −5 to 38 MPa and increased in the following order: PMDA-PDA < BPDA-PDA < PMDA-ODA < BPDA-ODA. The hardness of the polyimide films increased in the following order: PMDA-ODA < BPDA-ODA < PMDA-PDA < BPDA-PDA. The PDA-based polyimide films showed relatively lower residual stress and higher hardness than the corresponding ODA-based polyimide films. The in-plane orientation and molecularly ordered phase were enhanced with the increasing order as follows: PMDA-ODA < BPDA-ODA < BPDA-PDA ∼ PMDA-PDA. The PDA-based polyimides, having a rigid structure, showed relatively better-developed morphological structure than the corresponding ODA-based polyimides. The residual stress behavior and mechanical properties were correlated to the morphological structure in polyimide films. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Two series of semi-interpenetrating polymer network (semi-IPN) composite films, PEI/bismaleimide (UTBM) and PEI/fluorinated BMI (UTFBM) were prepared using a thermoplastic PEI and two different crosslinkable imide moieties. The effects of chemical structure and content of crosslinkable imide moieties on thermal stability, dielectric properties, and water sorption have been investigated. Glass transition temperature and weight loss temperatures increased with increase in the content of crosslinkable imide moieties, indicating the enhanced thermal stability of the semi-IPN composite films. The refractive indices of the semi-IPN composite systems increased with increasing crosslinkable imide moieties due to the higher polarizabilities of atoms. The water sorption of the semi-IPN composite films was significantly decreased by the incorporation of crosslinkable imide moieties, which are interpreted by morphological structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Poly(methyl methacrylate)-block-polyurethane-block-poly(methyl methacrylate) tri-block copolymers have been synthesized successfully through atom transfer radical polymerization of methyl methacrylate using telechelic bromo-terminated polyurethane/CuBr/N,N,N,N″,N″-pentamethyldiethylenetriamine initiating system. As the time increases, the number-average molecular weight increases linearly from 6400 to 37,000. This shows that the poly methyl methacrylate blocks were attached to polyurethane block. As the polymerization time increases, both conversion and molecular weight increased and the molecular weight increases linearly with increasing conversion. These results indicate that the formation of the tri-block copolymers was through atom transfer radical polymerization mechanism. Proton nuclear magnetic resonance spectral results of the triblock copolymers show that the molar ratio between polyurethane and poly (methyl methacrylate) blocks is in the range of 1 : 16.3 to 1 : 449.4. Differential scanning calorimetry results show Tg of the soft segment at −35°C and Tg of the hard segment at 75°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

A series of the semi-interpenetrating polymer network (semi-IPN) membranes based on sulfonated polyimide and poly(ethylene glycol) diacrylate were prepared and characterized comparing with pure sulfonated polyimide membrane and commercially available membrane, Nafion® 117. The proton conductivity increased with the increase of poly(ethylene glycol) diacrylate contents in spite of the decrease in ion exchange capacity which is a key factor to improve the proton conductivity. The water stability of semi-IPN membranes containing poly(ethylene glycol) diacrylate is higher than the pure sulfonated polyimide membrane. Morphological structure showed that amorphous nature of the films also increased with the poly(ethylene glycol) diacrylate contents, which could make a crosslink, so that the crystallinity of polyimide could disappear. Semi-IPN membranes based on sulfonated polyimide and poly(ethylene glycol) diacrylate, which show good conductivity comparable to Nafion® 117 in the range of 20–50% content of poly(ethylene glycol) diacrylate, could be promising proton conducting membranes in fuel cell application.

BACKROUND: Polyimide films coated on copper are a potential new substrate for fabricating printed circuit boards; however, adhesion between the copper and polyimide films is often poor. The relations between residual stress and adhesion strength according to the development of molecular orientation of polyimide films with different chemical backbone structure coated on copper were studied. RESULTS: The effect of chemical structures on properties including the residual stress and the adhesion strength were widely investigated for four different polyimides. Diamine 4,4′-oxydianiline (ODA) and dianhydrides 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA), 4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4′-oxydiphthalic anhydride (ODPA) and 3,3′,4,4′-benzophenone tetracarboxylic dianhydride (BTDA) were used to synthesize polyimide. In an attempt to quantify the interaction of thermal mismatch with the polyimide films depending on various structures, residual stress experiments between polyimide film and CuSi wafer were carried out over a range of 25–400 °C using in situ thin film stress analysis. A universal test machine was used to conduct 180° peel test (ASTM D903-98) of polyimide film from cooper foil. The residual stress on CuSi (100) wafer decreased in the order 6FDA-ODA > BTDA-ODA > ODPA-ODA > PMDA-ODA, and the interfacial adhesion strength decreased in the order BTDA-ODA (5 N mm−2) > ODPA-ODA > PMDA-ODA > 6FDA-ODA. The results may suggest that the morphological structure, degree of crystallinity of chain orientation and packing significantly relate to the residual stress and adhesion strength in polyimide films. Wide-angle X-ray diffraction was used for characterizing the molecular order and orientation and X-ray photoelectron spectroscopy was used for the analysis of components on copper after polyimide films were detached to confirm the existence of copper oxide chemical bonding and to measure the binding energy of elements on the copper surface. CONCLUSION: In this research, it is demonstrated that BTDA-ODA polyimide has a low residual stress to copper, good adhesion property, good thermal property and low dielectric constant. Therefore, BTDA-ODA would be expected to be a promising candidate for a two-layer copper-clad laminate. Copyright © 2007 Society of Chemical Industry

Organic–inorganic composite membranes from partially aliphatic sulfonated polyimides and heteropolyacids (HPAs) were synthesized. A series of composite membranes with varying amounts of heteropolyacid were prepared by altering the weight ratio of polyimide and HPA. The partially aliphatic sulfonated polyimides are synthesized from 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4′-diaminobiphenyl 2,2′-disulfonic acid as the sulfonated diamine, and decamethylenediamine as the aliphatic diamine. The incorporation of HPA is confirmed by FT-IR analyses. When appropriately embedded in a hydrophilic polymer matrix, the hydrated HPAs are expected to endow the composite membrane with their high proton conductivity, while retaining the desirable mechanical properties of the polymer film. These composite membranes were evaluated for thermal stability, ion exchange capacity, water uptake and proton conductivity. Also the extraction of HPA from the polyimide membranes and their stability in water were determined. Though water uptake and IEC decreased with increase in HPA content, the proton conductivity of the composite membranes increased with increase in HPA weight content. This study shows that partially aliphatic sulfonated polyimide composite membranes with HPA can be a viable substitute for Nafion ® for fuel cells which show good conductivity comparable to Nafion ® 117 at temperatures nearing 100 °C, keeping in mind that polyimides have good thermal stability and low cost.

To investigate the difference of the trifluoromethyl (CF 3 ) group and ether group affecting the optical property of fluorinated polyimides (PIs), we prepared 4,4′-bis(4-amino-2-trifluoromethylphenoxy)diphenyl ether ( 4 ) with three ether groups and 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane ( 5 ) with four CF 3 groups with 2-chloro-5-nitrobenzotrifluoride and 4,4′-dihydroxydiphenyl ether or 2,2-bis(4-hydroxyphenol)hexafluoropropane. Two series of organosoluble and light-colored PIs ( 4a – 4c , 5a – 5c ) were synthesized from 4 and 5 with various aromatic dianhydrides: 3,3,4,4-benzophenonetetracarboxylic dianhydride (BTDA) ( a ), 4,4-oxydiphthalic anhydride (ODPA) ( b ), and 4,4-hexafluoroisopropylidenediphthalic anhydride (6FDA) ( c ), prepared through a typical two-step polymerization method. These PIs were soluble in amide polar solvents and even in less polar solvents. The glass-transition temperatures ( T g ) of 4a – 5c were 221–249 °C and the 10% weight-loss temperatures were above 530 °C. Their films had cutoff wavelengths between 339 and 399 nm and yellowness index ranges from 1.95 to 42.60. The dielectric constants estimated from the average refractive indices are 2.59–2.93 (1 MHz). In a comparison of the PI series based on 4 , 5 , and 4,4′-bis(4-amino-2-trifluoromethylphenoxy)biphenyl ( 6 ), we found that the CF 3 group and ether group on the diamine had almost same effect in lowering the color, but the ether group had better thermal stability. The color intensity of the three PI series was lowered in the following order: 6 > 4 > 5 . The PI 5c , synthesized from diamine 5 and dianhydride c , had six CF 3 groups in a repeated segment and ether group at the same time, so it exhibited the lightest color among the three series.

In this work, we prepared epoxy/BMI composites by usingN,N′-bismaleimide-4,4′-diphenylmethane (BMI), epoxy resin (diglycidyl ether of bisphenol-A (DGEBA)), and 4,4’-diamino diphenyl methane (DDM). The thermal properties and water sorption behaviors of the epoxy and BMI composites were investigated. For the epoxy/ BMI composites, the glass transition and decomposition temperatures both increased with increasing BMI addition, which indicates the effect of BMI addition on improved thermal stability. The water sorption behaviors were gravimetrically measured as a function of humidity, temperature, and composition. The diffusion coefficient and water uptake decreased and the activation energy for water diffusion increased with increasing BMI content, indicating that the water sorption in epoxy resin, which causes reliability problems in electronic devices, can be diminished by BMI addition. The water sorption behaviors in the epoxy/BMI composites were interpreted in terms of their chemical and morphological structures.

Semi-interpenetrating polymer network (semi-IPN) membranes based on novel sulfonated polyimide (SPI) and poly (ethylene glycol) diacrylate (PEGDA) have been prepared for the fuel cell applications. SPI was synthesized from 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,4′-diaminobiphenyl 2,2′-disulfonic acid, and 2-bis [4-(4-aminophenoxy) phenyl] hexafluoropropane. PEGDA was polymerized in the presence of SPI to synthesize semi-IPN membranes of different ionic contents. These membranes were characterized by determining, ion exchange capacity, water uptake, water stability, proton conductivity, and thermal stability. The proton conductivity of the membranes increased with increasing PEGDA content in the order of 10−1 S cm−1 at 90°C. These interpenetrating network membranes showed higher water stability than the pure acid polyimide membrane. This study shows that semi-IPN SPI membranes based on PEGDA which gives hydrophilic group and structural stability can be available candidates comparable to Nafion® 117 over 70°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

The features of norbornene (NE) cross-linked polyimide (PI) were investigated as the ratio of the norbornene monomer was varied. The coefficient of thermal expansion and modulus are important parameters of materials used in the microelectronic industry. Therefore, in this study, 5-norbornene-2, 3-dicarboxylic acid (NE) was introduced as a crosslinking agent to increase the thermal stability at elevated temperatures. 4,4′-Benzophenonetetracarboxylic dianhydride was utilized as a dianhydride and 4,4′-diaminodiphenyl ether was introduced as a diamine monomer. By changing the ratio of each monomer, we were able to control the spacing of the chain and ring opening polymerization, which resulted in improved properties. Each sample was thermally cured which led to a ring opening mechanism of the norbornene through the reverse Diels-Alder reaction. Thermal mechanical analysis was utilized to determine the coefficient of thermal expansion and dynamic mechanical analysis was used to determine the storage modulus (e′) and loss modulus (e″) of the PI film. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42607.

A series of six-membered sulfonated polyimides with aliphatic linkages (SPIAs) was successfully synthesized using 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), 4,4′-diaminobiphenyl 2,2′-disulfonic acid (BDSA) as the sulfonated diamine, and aliphatic diamines H2N(CH2)nNH2 where n = 6, 8, 10, 12. These SPIAs were evaluated for thermal stability, ion exchange capacity (IEC), water uptake, proton conductivity, and hydrolytic stability. Proton conductivity and hydrolytic stability of the SPIAs were compared with the fully aromatic polyimide (MDA-SPI) prepared from 4,4′-methylenedianiline (MDA), BDSA, and NTDA. All the SPIAs exhibited high thermal stability. As the chain length of the aliphatic diamine decreased, the IEC and water uptake of the SPIAs increased. The SPIAs showed higher proton conductivity than commercially available membranes such as Nafion 117 at high temperatures and higher proton conductivity than MDA-SPI at all temperatures. All SPIAs exhibited a hydrolytic stability more than twice as high as that of MDA-SPI. Copyright © 2006 Society of Chemical Industry

To synthesize new functional poly(urethane-imide) crosslinked networks, soluble polyimide from 2,2′-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 4,4′-oxydianiline, and maleic anhydride and polyurethane prepolymer from polycaprolactone diol, tolylene 2,4-diisocyanate and hydroxyl ethyl acrylate were prepared. Poly(urethane-imide) thin films were finally prepared by the reaction between maleimide end-capped soluble polyimide (PI) and acrylate end-capped polyurethane (PU). The effect of polyurethane content on dielectric constant, residual stress, morphology, thermal property, and mechanical property was studied by FTIR, prism coupler, Thin Film Stress Analyzer (TFSA), XRD, TGA, DMTA, and Nano-indentation. Dielectric constant of poly(urethane-imide) thin films (2.39–2.45) was lower than that of pure polyimide (2.46). Especially, poly(urethane-imide) thin films with 50% of PU showed lower dielectric constant than other poly(urethane-imide) thin films did. Lower residual stress and slope in cooling curve were achieved in higher PU content. Compared to typical polyurethane, poly(urethane-imide) thin films exhibited better thermal stability due to the presence of the imide groups. The glass transition temperature, modulus, and hardness decreased with increase in the flexible PU content even though elongation and thermal expansion coefficient increased. Finally, poly(urethane-imide) thin films with low residual stress and dielectric constant, which are strongly affected by the morphological structure, chain mobility, and modulus, can be suggested to apply for electronic devices by variation of PU. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 113–123, 2006