Biphthalic Anhydride Research Articles

Enhanced performance of low-dielectric siloxane-polyimide copolymers: Synthesis and properties

Low-dielectric polyimides (PI) films with outstanding overall performance are attractive for next generation microelectronic applications. Herein, a series of two different FPIs and BPIs derived from 4,4′-diaminodiphenyl ether (ODA) and two different functional dianhydrides, 4,4'-(hexafluoroisopropylidene) biphthalic anhydride (6FDA) and 4,4′-(4,4′-isopropyldiphenoxy) biphthalic anhydride (BPADA), respectively, were synthesized by a conventional two-step methodology that included thermoimidatization. Additionally, employing aminopropyl-terminated polydimethylsiloxane PDMS (molecular weight = 1000) as the source of siloxane-oxygen bonds, a series of polyimide siloxane (SiFPIs and SiBPIs) copolymers were synthesized by varying the siloxane content (ranging from 0 to 5 wt%) within the copolymer structure. The effects of siloxane bond on the thermal, solubility, water resistance, dielectric and mechanical properties of polyimide were investigated systematically. The integration of siloxane significantly enhanced the solubility of these copolymers in polar aprotic solvents (DMAC, DMF, NMP), expanding their applicability in diverse processing environments. Crucially, these copolymers exhibited remarkably low dielectric constants—2.90 for SiFPI at 3% PDMS and 2.92 for SiBPI at 4% PDMS—coupled with low loss values, positioning them as prime candidates for advanced microelectronic applications. All the composite films have high thermal stability near pure PI. The introduction of PMDS into PI can improve the elongation at break and at the same time, the composite films still remained with higher modulus and tensile strength. Extensive hydrophobicity assessments through contact angle and water absorption studies underscored the copolymers’ superior moisture resistance, a critical parameter for their potential deployment in high-performance, environmentally sensitive electronic components.

High-temperature semicrystalline/amorphous polymer blends exhibiting enhanced dielectric constant with high breakdown strength

High-temperature polymers with high dielectric constant (K) and breakdown strength are of great interest in many electronic and electric devices and systems. Blending different polymers is a general and highly scalable strategy to improve polymer performance. We investigate two types of semicrystalline polyimide (PI) with different chemical structures blended with amorphous polymer poly (1,4-phenylene ether sulfone) (PES). They formed immiscible polymer blends and exhibited distinctively semicrystalline/amorphous behaviors. The blends of 4,4’-biphthalic anhydride (BPDA)-typed PI with PES form semicrystalline polymer phases and the blend at 50/50 wt% composition exhibits an increased dielectric constant while maintaining the high breakdown field of the neat PI(BPDA) at Eb of 600 MV/m. In contrast, blends of pyromellitic dianhydride (PMDA)-typed PI and PES, which form amorphous phases, show a dielectric increase but a large reduction in Eb. Computational simulations indicate that PI(BPDA) assumes a preferred orientation on PES, which expedites crystallization, while overlaying PI(PMDA) on PES results in more disorder and larger voids. Our finding that the PI(BPDA)/PES blends at 50/50 wt% composition generates enhancement in K without negatively affecting Eb is the first in polymer blends. The results suggest that strategically designing high-temperature polymer blends and exploiting the crystallites within the polymer matrix can achieve an enhanced dielectric constant while maintaining a high breakdown strength. This approach is highly scalable and low cost, thus paving the way for developing practical and high-performance dielectric polymers with high energy density and broad operating temperatures.

Colorless and transparent polyimide nanocomposites using organically modified montmorillonite and mica

In this study, we introduce a method for replacing the glass used in existing display electronic materials, lighting, and solar cells by synthesizing a colorless and transparent polyimide (CPI) film with excellent mechanical properties and thermal stability using a combination of new monomers. Poly(amic acid) (PAA) was synthesized using dianhydride 4,4′-biphthalic anhydride (BPA) and diamine 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (AHP). Various contents of organically modified montmorillonite (MMT) and mica were dispersed in PAA solution through solution intercalation, and then CPI hybrid films were prepared through multi-step thermal imidization. The organoclays synthesized to prepare CPI hybrid films were Cloisite 93A (CS-MMT) and hexadimethrine-mica (HM-Mica) based on MMT and mica, respectively. In particular, the diamine monomer AHP containing a –OH group was selected to increase the dispersibility and compatibility between the hydrophilic clays and the CPI matrix. To demonstrate the characteristics of CPI, the overall polymer structure was bent and a strong electron withdrawing –CF3 group was used as a substituent. The thermomechanical properties, morphology of clay dispersion, and optical transparency of the CPI hybrid films were investigated and compared according to the type and content of organoclays. Two types of organoclays, CS-MMT and HM-Mica, were dispersed in a CPI matrix at 1 to 7 wt%, respectively. In electron microscopy, most of the clays were uniformly dispersed in a plate-like shape of less than 20 nm at a certain critical content of the two types of organoclays, but agglomeration of the clays was observed when the content was higher than the critical content. Hybrids using HM-Mica had better thermomechanical properties and hybrids containing CS-MMT had better optical transparency.

Multiscale Interfacial Regulation of Zn‐V2O5 Pouch Cell via Ultrathin Molecular‐Engineered Separator

AbstractRechargeable aqueous zinc batteries (RAZBs) suffer from the structural degradation of the layered oxide cathode, parasitic side reaction on the Zn foil as well as often‐overlooked self‐discharge phenomenon at the elevated temperatures. Herein, this study presents a thin‐layer (9 µm) molecular‐engineered separator strategy to achieve the concurrent shelf life, cycling endurance, as well as the practical energy density for the RAZBs prototype. On the face‐to‐cathode side, the biphthalic anhydride is anchored onto the polyethylene separator substrate (PE) via a robotic arm‐controlled spray‐coating method, inhibiting the spontaneous vanadium dissolution and shuttle at both the dynamic cycling or static high‐temperature storage; meanwhile the 3,3′‐diamino‐4,4′‐dihydroxydiphenyl sulfone molecular tailoring on the face‐to‐anode side provides ion‐sieving capability to repel detrimental SO42−, yet guiding uniform Zn2+ influx and preferential deposits accumulation along the (002) crystallographic orientation even at the extreme deposition scenario (20 mA cm−2, 20 mAh cm−2). Upon the layer‐stacked assembly of the V2O5 cathode (2.0 mAh cm−2), molecular‐engineered separator as well as the Zn foil (20 µm), the 0.78 Ah pouch‐format prototype exhibits the superior volumetric/gravimetric energy densities of 133.3 Wh L−1/71.4 Wh kg−1 and extreme power output (444.3 W L−1/238.0 W kg−1).

Monomer Dependence of Colorless and Transparent Polyimide Films: Thermomechanical Properties, Optical Transparency, and Solubility.

Six poly(amic acid)s (PAAs) were synthesized by reacting bis(3-aminophenyl) sulfone with various dianhydride monomers such as pyromellitic dianhydride, 4,4'-biphthalic anhydride, dicyclohexyl-3,4,3',4'-tetracarboxylic dianhydride, 4,4'-oxidiphthalic anhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, and 4,4'-(hexafluoroisopropylidene) diphthalic anhydride. These PAAs were then converted to polyimide (PI) films by thermal imidization at various temperatures. To obtain colorless and transparent PI (CPI), the dianhydride monomer used in this study had an overall bent structure, a structure containing a strong electron-withdrawing -CF3 substituent or an alicyclic ring. In addition, some monomers contained ether or ketone functional groups in their bent structures. The thermomechanical properties, optical transparency, and solubility of CPI films with six different dianhydride monomer structures were investigated, and the correlation between the monomer structure and CPI film properties was clarified. Overall, CPI with an aromatic main chain structure or a linear structure had excellent thermal and mechanical properties. In contrast, CPI with a bent structure containing functional groups or substituents in the main chain exhibited excellent optical transparency and solubility.

Effect of organoclay on the physical properties of colorless and transparent copoly(amide imide) nanocomposites.

Copoly(amic acid) was prepared using the diamine monomer N,N'-[2,2'-bis(trifluoromethyl)-4,4'-biphenylene]bis(4-aminobenzamide) (TFAB) and the anhydride monomers 4,4'-(hexafluoro-isopropylidene)diphthalic anhydride (6FDA) and 4,4'-biphthalic anhydride (BPA). Thereafter, a colorless and transparent copoly(amide imide) (Co-CPAI) film was synthesized through various heat treatments. Co-CPAI hybrid films with a TFAB : 6FDA : BPA molar ratio of 1 : 0.5 : 0.5 were subsequently fabricated using organically modified hectorite (STN) with various contents ranging from 0 to 7 wt% via the solution intercalation method. Finally, the thermomechanical properties, clay dispersion, and optical transmittance of the hybrid films were investigated. The results of wide-angle X-ray diffractometry and transmission electron microscopy demonstrated good dispersion at low clay loadings; however, clay agglomeration was observed above a certain critical STN content. At the critical STN content of 3 wt%, the clay was evenly distributed in the matrix with a nanoscale thickness of approximately 10 nm. Hybrid films containing 3 wt% STN showed excellent thermomechanical properties. Beyond this critical clay content, the physical properties of the films decreased because of the agglomeration of excess clay. Regardless of the clay content, however, the optical properties of the hybrid films remained constant, and their yellow indices, which ranged from 2 to 4, indicated excellent colorless transparency.

Efficient photocatalytic H2 production of g-C3N4 using nickel (II) functional complex as promoter

With the increasingly prominent energy and environmental problems, the construction of sustainable development, green environmental protection and new efficient energy system has become the focus of the world's attention. Photocatalytic hydrogen production technology is an important way to solve energy and environmental problems. The key to realizing the visible light catalytic water hydrogen production technology effectively lies in the selection of photocatalytic materials, graphite phase carbon nitride (g-C3N4) is an important photocatalyst. However, the photocatalytic performance of g-C3N4 is severely limited by the high recombination rate of photogenerated electron-hole pairs. Functional complex has a matching band gap with carbon nitride to form heterojunction structure, which can effectively reduce the photogenic carrier recombination and improve the catalytic hydrogen production performance. For this reason, the functional complex [Ni2(Medpq)2(BPDA)·2H2O] (BPDA = 4,4′-Biphthalic Anhydride, Medpq = 2-methyldipyrido[3,2-f:2′,3′-h]quinoxaline) was synthesized by a hydrothermal process. The matching band gap between [Ni2(Medpq)2(BPDA)·2H2O] and g-C3N4 forms heterojunction structure, which effectively solve the defect of low utilization rate of light energy and improve the catalytic hydrogen production performance of g-C3N4. The experiment proved that complex/g-C3N4 photocatalytic rates of hydrogen production 2054.13 μmol·h−1·g−1, about 5.04 times that of pure g-C3N4 (407.56 μmol·h−1·g−1), thus high-performance of the hydrogen production from water decomposition was realized.

Comparison of the properties of polyimide nanocomposite films containing functionalized-graphene and organoclay as nanofillers

Poly(amic acid) (PAA) is prepared by the reaction of dianhydride 4,4′-biphthalic anhydride and diamine bis[4-(3-aminophenoxy)phenyl]sulfone in N,N’-dimethylacetamide. Two types of fillers were dispersed in the as-synthesized PAA via a solution intercalation method; polyimide (PI) hybrid films were synthesized under various heat treatment conditions. Octylamine (C8) was introduced into graphene sheets (C8-GS) and bentonite (C8-BTN), which were then used as nanofillers in the PI hybrid films. The synthesized nanofillers were used in varying amounts of 0.25–1.00 wt% with respect to the matrix PI. The thermal and morphological properties and optical transparency of the hybrid films were investigated and compared for both C8-GS and C8-BTN at varying nanofiller content. The C8-BTN nanocomposite showed superior thermal properties, and optical transparency, and the filler was well dispersed in the PI matrix compared to the C8-GS nanocomposite. The thermal stability of the hybrid films improved upon the addition of small amounts of the nanofiller. However, beyond a certain critical filler concentration, the thermal stability declined. These results were verified through the dispersion of fillers via transmission electron microscopy.

Effect of structural isomerism on physical and gas transport properties of Tröger's Base-based polyimides

The physical and gas transport properties of Tröger's Base (TB)-based polyimides (PI-TBs) synthesized by isomeric monomers were rarely reported. Here, a series of PI-TBs was synthesized from two iso-ether dianhydrides [4,4′-oxydiphthalic anhydride (4,4′-ODPA)/3,4′-oxydiphthalic anhydride (3,4′-ODPA)] and two iso-biphenyl dianhydrides [3,3′,4,4′-biphenyltetracarboxylic dianhydride (4,4′-BPDA)/3,4′-biphthalic anhydride (3,4′-BPDA)], with two diamines, 2,5-dimethyl-1,4-phenylenediamine (DPD) or 2,6-diaminotoluene (DAT). The solubility, microporosity, chain packing, mechanical performance and thermal stability, and gas transport properties were investigated for the PI-TBs derived from the isomeric dianhydrides. The polyimides derived from DPD and appropriate dianhydrides had better solubility and film-forming capability, mechanical properties, and higher gas permeability than those from DAT analogues. Furthermore, the polyimides based on different isomeric dianhydrides showed good solubility, mechanical properties, and high thermal stability and glass transition temperatures (Tgs), up to 400 °C. The chemical structures of isomeric dianhydrides have a noticeable influence on the chain packing and gas separation performance of the PI-TBs. The PI-TBs with rigid 3,4’-/4,4′-BPDA residues showed microporosity and their BET values in the range of 235.2–324.9 m2/g. The PI-TB membranes from the 3,4′-BPDA showed both higher gas permeability and selectivity (H2/CO2, H2/CH4, CO2/CH4) compared to those from the 4,4′-BPDA. On the contrary, the PI-TB membranes from the 3,4′-ODPA had lower gas permeability with improved gas selectivity compared to those from the corresponding 4,4′-ODPA.

Colorless and Transparent Copolyimides and Their Nanocomposites: Thermo-Optical Properties, Morphologies, and Gas Permeabilities.

A series of linear aromatic copolyimides (Co-PIs) were synthesized by reacting 4,4′-biphthalic anhydride (BPA) with various molar contents of 2,2′-bis(trifluoromethyl)benzidine (TFB) and p-xylylenediamine (p-XDA) in N,N′-dimethylacetamide (DMAc). Co-PI films were fabricated by solution casting and thermal imidization with poly(amic acid) (PAA) on glass plates. The thermo-optical properties and gas permeabilities of Co-PI films composed of various molar ratios of p-XDA (0.2–1.0 relative to BPA) were investigated. Thermal properties were observed to deteriorate with increasing p-XDA concentration. However, oxygen-transmission rates (O2TRs) and optical transparencies improved with increasing p-XDA concentration. Co-PI hybrids with a 1:0.2:0.8 molar ratio of BPA:TFB:p-XDA and organically modified hectorite (STN) were prepared by the in situ intercalation method. The morphologies and the thermo-optical and gas permeation properties of the hybrids were examined as functions of STN loading (5–50 wt %). XRD and TEM revealed substantial increases in clay particle agglomeration in the Co-PI hybrid films as the clay loading was increased from 5 to 50 wt %. The coefficient of thermal expansion (CTE) and the O2TR of a Co-PI hybrid film were observed to improve with increasing STN concentration; however, its optical transparency decreased gradually with increasing STN concentration.

Synthesis and characterization of colorless polyimides derived from 4-(4-aminophenoxy)-2,6-dimethylaniline

A new aromatic polyimides (PIs) having asymmetric aromatic diamine with methyl groups at the ortho position of amino group has been developed to prepare transparent film in the visible region. The all aromatic PIs presented here are derived from 4-(4-aminophenoxy)-2,6-dimethylaniline (APDMA) and aromatic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4'-oxydiphthalic anhydride (ODPA), 4,4'-biphthalic anhydride (BPDA), and pyromellitic dianhydride (PMDA) via a two-step polycondensation. All PIs show good thermal properties: 5% weight loss at a temperature range of 510-529 °C and their glass transition temperature found above 290 °C. The PIs exhibit good optical transparency, such as cut-off wavelength in the region of 296-358 nm and above 92-99% at 550 nm. In addition, all PIs show low refractive indices in the range of 1.567-1.637 at wavelength of 637 nm and low birefringence.

Syntheses and Characterizations of Colorless and Transparent Poly(amide imide) Copolymer

4-nitrobenzoyl chloride와 2,2"-bis(trifluoromethyl)benzidine(TFB)를 이용하여 N,N"-[2,2"-bis(trifluoromethyl)-4,4"-biphenylene]bis(4-aminobenzamide)(TFAB)의 아민 단량체를 합성하였다. 합성된 TFAB와 무수물 단량체인 4,4"-(hexafluoro-isopropylidene) diphthalic anhydride(6FDA) 및 4,4"-biphthalic anhydride(BPA)를 다양한 몰 비로 반응하여 폴리아믹산(polyamic acid, PAA)을 합성한 후 화학적-열적 이미드화 반응을 거쳐 아미드 그룹을 가지는 폴리이미드 공중합체(Co-PI)를 합성하였다. 용액 캐스팅으로 합성된 Co-PI 필름은 유연하고 질긴 성질을 보였다. 합성된 Co-PI는 BPA의 함량 변화에 따라 열적-기계적 성질 및 광학 투명도 등을 조사하였다. Co-PI 필름의 열 팽창 계수(coefficient of thermal expansion, CTE) 값은 BPA의 몰 비가 증가할수록 감소하였지만, 광학 투명성에서는 반대의 결과를 보여주었다. N,N"-[2,2′-bis(trifluoromethyl)-4,4′-biphenylene]bis(4-aminobenzamide) (TFAB) was synthesized from 4-nitrobenzoyl chloride and 2,2′-bis(trifluoromethyl)benzidine (TFB). The obtained TFAB, 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), and 4,4′-biphthalic anhydride (BPA) were used to synthesize polyimide copolymers(Co-PIs) containing amide groups. Flexible and tough Co-PI films were prepared from poly(amic acid) (PAA) through solution-casting using chemical and thermal imidization methods. The thermomechanical properties and optical transparency of the Co-PI films with various BPA monomer contents were investigated. The coefficients of thermal expansions (CTEs) of the Co-PI films were improved linearly with increasing BPA content. However, their optical transparency was found to worsen with increasing BPA content.

Synthesis and characterization of highly-fluorinated colorless polyimides derived from 4,4′-((perfluoro-[1,1′-biphenyl]-4,4′-diyl)bis(oxy))bis(2,6-dimethylaniline) and aromatic dianhydrides

The authors report the synthesis and characterization of a polyimide (PI) series derived from 4,4′-((perfluoro-[1,1′-biphenyl]-4,4′-diyl)bis(oxy))bis(2,6-dimethylaniline) (8FBPODMA). The 8FBPODMA monomer containing a perfluorobiphenyl group with two 2,6-dimethylaniline units connected by an ether bond was synthesized and polycondensed with several aromatic dianhydrides, including 4,4′-biphthalic anhydride (BPDA), 4,4′-oxydiphthalic anhydride (ODPA), pyromellitic dianhydride (PMDA), and 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), by the traditional two-step imidization procedure. All PIs shows high optical transparency, higher than 80% at 500 nm for a thickness of ca. 10 μm and good thermal properties. The thermal decomposition temperatures (T10%) of the PIs are in the range of 507–527 °C and the glass transition temperatures (Tg) are in the range of 280–345 °C. In addition, the PIs have low refractive indices because of their high fluorine contents. In particular, 8FBPODMA–6FDA shows a very low refractive index (1.5389) and a low birefringence (0.0054) at 637 nm.

Polyimide nanocomposites with novel functionalized‐graphene sheet: thermal property, morphology, gas permeation, and conductivity

4‐Amino‐N‐hexadecylbenzamide‐graphene sheets (AHB‐GSs), used in the preparation of polyimide (PI) nanocomposite films, were synthesized by mixing a dispersion of graphite oxide with a solution of the ammonium salt of AHB. The atomic force microscopy image of the AHB‐GSs on mica and a profile plot revealed the average sheet thickness to be ~3.21 nm. PI films were prepared by reacting 4,4'‐biphthalic anhydride and bis(4‐aminophenyl) sulfide. PI nanocomposite films containing different amounts of AHB‐GS (0–10 wt%) were compared for their morphologies, thermal properties, gas permeation, and electrical and thermal conductivities. The graphenes, for the most part, were well dispersed in the polymer matrix despite some agglomeration. However, micrometer‐scale particles were not detected. The average thickness of the particles was less than 10 nm, as revealed from the transmission electron microscope images. Only a small amount of AHB‐GS was required to improve the coefficient of thermal expansion, gas permeation, and electrical and thermal conductivities. In contrast, the glass transition temperature and initial decomposition temperature of the PI hybrid films continued to decrease with increasing AHB‐GS content up to 10 wt%. Copyright © 2015 John Wiley & Sons, Ltd.

Synthesis and characterization of high refractive index polyimides derived from 2,5-Bis (4-Aminophenylenesulfanyl)-3,4-Ethylenedithiothiophene and aromatic dianhydrides

The authors describe the synthesis and characterization of the polyimide (PI) series containing a 2,5-bis(4-aminophenylenesulfanyl)-3,4-ethylenedithiothiophene (APSEDTT) moiety in their main chain. The APSEDTT monomer with high sulfur content was prepared and polymerized with several aromatic dianhydrides such as 4,4′-[p-thio bis(phenylenesulfanyl)]diphthalic anhydride (3SDEA), 4,4′-biphthalic anhydride (BPDA), and 4,4′-oxydiphthalic anhydride (ODPA) by the traditional two-step polycondensation procedure. All PIs exhibited high transparency, higher than 75% at 550 nm for a thickness of about 20 μm and good thermal properties such as thermal decomposition temperatures (T10%) in the range of 409–521 °C. In addition, the PIs have extraordinarily excellent optical properties in refractive index and birefringence as originally designed. In particular, the PI derived from APSEDTT and 3SDEA showed a high refractive index (1.7586), and a low birefringence (0.0087) because of their very high sulfur content (27.7%). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 944–950

열 이미드화 온도에 따른 작용기화 그래핀/폴리이미드 나노복합재료

폴리이미드(PI) 나노복합체 필름 제조에 사용된 작용기화 4-amino-N-hexadecylbenzamide graphene sheets (AHB-GSs)는 graphene oxide 분산액에 4-amino-N-hexadecylbenzamide(AHB)를 반응시켜 합성하였다. AHB-GS의 주사탐침 현미경(atomic force microscope, AFM) 이미지와 모식도를 통해서 AHB-GS의 평균 두께가 약 3.21 nm임을 확인하였다. PI는 4,4'-biphthalic anhydride와 bis(4-aminophenyl)sulfide를 사용하여 합성하였다. PI 나노복합체는 0-10 wt%의 다양한 함량의 AHB-GS를 용액 삽입(solution intercalation) 방법을 사용하여 합성하였고, 이미드화는 각각 <TEX>$250^{\circ}C$</TEX> 및 <TEX>$350^{\circ}C$</TEX>까지 열 처리하였다. AHB-GS는 대부분 고분자 매트릭스에 잘 분산되었고 약간 뭉친 것도 있었지만 마이크로미터 수준의 입자는 관찰되지 않았다. TEM으로 관찰하였을 때, 평균적으로 입자의 두께는 10 nm 미만이었다. PI 복합체 필름 중 소량의 AHB-GS만으로도 가스 투과도와 전기 전도도는 향상되었지만, 반대로 유리전이 온도와 초기 분해 온도는 AHB-GS의 함량이 10 wt%까지 증가함에 따라 지속적으로 감소되는 경향을 보였다. 전체적으로는, <TEX>$250^{\circ}C$</TEX>까지 이미드화한 PI에 비해 <TEX>$350^{\circ}C$</TEX>까지 열처리한 PI 필름이 보다 향상된 특성을 보였다. 4-Amino-N-hexadecylbenzamide-graphene sheets (AHB-GSs), used in the preparation of the polyimide (PI) nanocomposite films, were synthesized by mixing a dispersion of graphite oxide with a solution of the ammonium salt of AHB. The atomic force microscope image of functionalized-GS on mica and a profile plot revealed the average thickness of AHB-GS to be ~3.21 nm. PI films were synthesized by reacting 4,4'-biphthalic anhydride and bis(4-aminophenyl) sulfide. PI nanocomposite films containing various contents of AHB-GS over the range of 0-10 wt% were synthesized using the solution intercalation method. The PI nanocomposite films under different thermal imidization temperatures, 250 and <TEX>$350^{\circ}C$</TEX>, were examined. The graphenes, for the most part, were well dispersed in the polymer matrix despite some agglomeration. However, micrometer-scale particles were not detected. The average thickness of the particles was <10 nm, as revealed from the transmission electron microscope images. Only a small amount of AHB-GS was required to improve the gas barrier, and electrical conductivity. In contrast, the glass transition and initial decomposition temperatures of the PI hybrid films continued to decrease with increasing content of AHB-GS up to 10 wt%. In general, the properties of the PI hybrid films heat treated at <TEX>$350^{\circ}C$</TEX> were better than those of films heat treated at <TEX>$250^{\circ}C$</TEX>.

Study of yellow luminescence of binary terbium complexes based on 3,3′,4,4′-biphthalic anhydride

Three novel binary Tb(III) complexes (TbL2, TbL, and Tb2L; L=3,3',4,4'-biphenyl tetracarboxylic ligand) were synthesized by changing the molar ratio of Tb(III) to 3,3',4,4'-biphthalic anhydride (BPDA) (1∶2, 1∶1, and 2∶1, respectively). IR spectra indicate that there are two coordination modes of the carboxylate ligands with Tb3+ ions in the complexes. Most of them are in bridging mode; the others are in chelating mode. These complexes all have good thermal stability. The photophysical properties of these complexes are studied in detail using UV absorption spectra, fluorescence spectra, and transient fluorescence spectra. The results indicate that the photoluminescence properties of the complexes depend strongly on the molar ratio of Tb(III) to BPDA. When the molar ratio of Tb(III) to BPDA is 1∶1, complex TbL exhibits the strongest yellow light emission among the three Tb(III) complexes. However, complex Tb2L exhibits a weaker yellowish-green light emission when the molar ratio of Tb(III) to BPDA is 2∶1. The phenomenon of the yellow emission from terbium complexes is rarely reported.

Two Series of Multicomponent Rare Earth (Eu3+, Tb3+, Sm3+) Polymeric Hybrids: Chemically Bonded Assembly and Photophysical Properties

In the present work, two new chemical linkages (BPDA-PAM, BPDA-DG) are synthesized through the reaction between 4,4'-biphthalic anhydride (BPDA) and acrylamide (AM), diethylene glycol (DG), respectively. Then two novel series of multicomponent rare earth (Eu(3+), Tb(3+), Sm(3+)) polymeric hybrids have been assembled through the coordination bonding: one is from the linkage BPDA-PAM to form the hybrids BPDA-PAM-RE-phen(bipy) (2,2'-bipyridine (bipy) and 1,10-penanthroline (phen)), the other is from the linkage BPDA-DG to compose the hybrids BPDA-DG-RE-PVP and PVP (PVP = poly vinylpyridine). These hybrids are characterized and especially the photophysical properties (luminescence spectra, lifetimes and quantum efficiencies) are discussed in detail.

Formation of metal thin nanocomposite layer from precursor polyimide containing metal complex

Herein, we report on fabrication of nickel nanocomposite on polyimide resin via a direct metallization process using nickel complexes as the nickel precursor. The process relies on synthesis of poly(amic acid) solutions containing nickel complex formed from 4,4'-biphthalic anhydride (BPDA)/2,2'-Bis[4-(4-aminophenoxy)phenyl]propane (BAPP) and formation of poly(amic acid) films containing nickel complex followed by chemical reduction. Nickel nanoparticles could be seen to form on the surface and into the precursor polyimide film. The thin nickel nanocomposite films could be used as precursors for copper clad on polyimide films; the copper clad on polyimide films were obtained by electroless nickel deposition and copper electrodeposition. The metal films were highly adhesive; the films readily pass the Scotch-tape test. These results suggest that the nanocomposite layer at the interfacial region acts as a glue between the deposited metal and polymer via a nanoscale interlocking effect.

Photo-Alignment Properties of Photo-Crosslinked Films of Liquid Crystalline Polymers Containing Chalcone Derivatives

ABSTRACT Side-chain polymethacrylates, side-chain polyimides, and main-chain polyimides containing chalcone derivatives were synthesized in order to investigate the photo-alignment behavior of liquid crystalline (LC) molecules in the LC cell fabricated from the polymer film irradiated with linearly polarized UV (LPUV) light under different conditions. The side-chain polyimides and the main-chain polyimides containing the 6FDA (4,4′-(hexafluoro-isopropylidene)-diphthalic anhydride) derivative are soluble in organic solvents and fusible, while the main-chain polyimides with the BPDA (4,4′-biphthalic anhydride) derivative show only fusibility. Only the polymethacrylate and main-chain polyimides with the BPDA derivative demonstrate a smectic A phase. The mixture of 4-cyano-4′-n-pentylbiphenyl (5CB) and dichroic dye was filled in the LC cell. In the LC cell using the polymethacrylate film irradiated in the LC state and the side-chain polyimide film irradiated above glass transition temperature, 5CB was easily aligned parallel to the electric vector of incident LPUV light, while 5CB in the LC cell using the irradiated main-chain polyimide film was aligned perpendicular to the electric vector of incident LPUV light.