Properties of an organosilicon nanophase generated in a poly(amide imide) matrix by the sol‐gel technique

Poly(amide imide) (PAI) nanocomposites prepared by the in situ generation of crosslinked organosilicon nanophase (ON) through the sol‐gel process were characterized by wide‐angle and small‐angle X‐ray diffraction, thermogravimetric analysis, dynamic mechanical analysis and kinetics of water uptake. It was concluded that the polymer nanocomposite (PNC) were likely to possess a complex morphology on the nanoscale characterized by co‐existence of two mixed nanophases of different compositions. At low methyl triethoxysilane (MTS) contents the fractal‐like organization of paracrystalline nano‐domains of PAI chain fragments is destroyed by the randomly distributed ON particles, whereas on the increase of MTS content the spatial correlations between ON particles become stronger, giving rise to their own fractal‐like structure. The higher values of small‐angle X‐ray scattering (SAXS) invariant, apparent water diffusivity and limiting water uptake for the PNC compared to the pristine PAI were assumed to reflect the loose inner structures of PAI‐rich and ON‐rich nanophases, respectively. Copyright © 2005 John Wiley & Sons, Ltd.     

A sol–gel polymerization method for creating nanoporous polyimide silsesquioxane nanostructures as soft dielectric materials

A sol–gel polymerization method was developed to make polyimide (PI) silsesquioxane (SSQ) nanoparticles as functional, soft dielectric materials. The surface functionalization of the polymer chain backbone and chain ends of poly(trimellitic anhydride chloride‐co‐4,4′‐methylenedianiline), PMR‐15 resin, with para‐(chloromethyl)‐phenylethyltrimethoxy silane yielded a novel sol–gel reactive sites functionalized PMR‐silane precursor. Upon base‐catalyzed hydrolysis and condensation of the PMR‐silane precursor, spherical, raspberry‐like PMR‐SSQ nanoparticles were obtained in considerably good yield. Controlling the particle size distribution was attempted upon adjusting the molar ratio between the silane precursor and the base, as well as in the presence of a catalytic amount of silica sols. Particle composition, thermal stability, and morphology were confirmed from Fourier transform infrared, thermogravimetric analysis, and scanning electron microscopy analyses. Nanoparticles, visualized under transmission electron microscopy exhibit a nanoporous structure. The Brunauer–Emmett–Teller analysis confirmed that the average pore dimension is ranged from 2 to 5 nm. The dielectric constant of PMR‐SSQ nanoparticles was as low as 1.95, compared to dielectric constants of 3.05 and 3.13 for PMR‐15 and PMR‐silane, respectively. Thus, the base‐catalyzed sol–gel polymerization of alkoxysilylated PI offers a novel synthetic path to make functional nanoporous PI nanostructures that possess ultralow dielectric constants. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 57, 562–571.     

Core–shell functionalized MWCNT/poly(m‐aminophenol) nanocomposite with large dielectric permittivity and low dielectric loss

Core–shell carboxyl‐functionalized multiwall carbon nanotube (c‐MWCNT)/poly(m‐aminophenol) (PmAP) nanocomposite were prepared through in‐situ polymerization of m‐aminophenol (m‐AP) in the presence of MWCNTs, and explicated as a dielectric material for electronic applications. The formation of thin PmAP layer on individual c‐MWCNT with excellent molecular level interactions at interfaces was confirmed by morphological and spectroscopic analyses. Here we conducted a comparative study of the dielectric performances of PmAP based nanocomposite films with pristine MWCNTs and c‐MWCNTs as fillers. Compared to PmAP/MWCNT nanocomposites, the PmAP/c‐MWCNT nanocomposites exhibited higher dielectric permittivity and lower dielectric loss. The well dispersed c‐MWCNTs in PmAP/c‐MWCNT nanocomposite produce huge interfacial area together with numerous active polarized centers (crystallographic defects), which in turn intensified the Maxwell‐Wagner‐Sillars (MWS) effect based on excellent molecular level interactions and thus, produce large dielectric permittivity (8810 at 1 kHz). The percolation threshold of PmAP/c‐MWCNT nanocomposites is found lower than that of the PmAP/MWCNT nanocomposites, which could be attributed to homogeneous distribution of c‐MWCNTs and strong c‐MWCNT//PmAP interfacial interactions in the nanocomposites. Copyright © 2016 John Wiley & Sons, Ltd.     

Effects of alicyclic moiety incorporation on the properties of polyimide/silica hybrid films

Polyimide (PI)/silica hybrid films were prepared from tetraethyl orthosilicate (TEOS) using a sol‐gel process as well as pyromellitic dianhydride and 4,4‐oxydianiline. 1,4‐Cyclohexanedicarboxylic acid (1,4‐CHDA) was added as a coupling agent. The PI/silica hybrid films were characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, differential scanning calorimetry and wide‐angle X‐ray diffraction. The thermal, tensile and dielectric properties of the hybrid films were measured. The results showed that the tensile and dielectric properties of the hybrid films improved with increasing silica concentration and 1,4‐CHDA content in the PI matrix. Covalent ester bonds were formed between SiOH groups of silica and carboxyl groups of 1,4‐CHDA. As a result, the silica particle size was reduced and dispersed homogeneously in the PI matrix, leading to increased tensile strength and tensile modulus of the typical hybrid film with 1,4‐CHDA (PI‐2), when compared with the PI/silica hybrid film without 1,4‐CHDA at the same silica contents. The presence of an alicyclic moiety containing silica in PI reduced the dielectric constant considerably to 2.83, which was lower than that of pristine PI. Copyright © 2016 John Wiley & Sons, Ltd.     

Dielectric properties of PANI-PEG nanocomposites filled with silica media for antistatic applications

The dielectric investigations of porous synthetic silica gel modified with polyaniline (PANI) and polyethylene glycol (PEG) polyblend at various concentrations are demonstrated in this paper. By using the chemical oxidative process to embed polyaniline (PANI) and polyethylene glycol (PEG) into a silica matrix, conducting gel nanocomposites were synthesized. For various dopant concentrations, the dielectric permittivity (ε′), D.C. conductivity (σ_dc), loss tangent (tanδ) and dielectric loss (ε″) were investigated. The samples were characterized using differential thermal analysis/thermogravimetric analysis, Fourier transform infrared spectroscopy and high-resolution transmission electron microscopy. Depending on the co-blend content, PANI-PEG modified silica structures produce nanoparticles ranging in size from 9.9 to 48.1 nm. The variation of DC conductivity (σ_dc) with PANI/PEG content shows Maxwell-Wagner Sillars (MWS) effect confirming the role of the conjugation and the structural order.     

Microstructure and properties of 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA)‐p‐phenylene diamine (PDA) polyimide/poly(vinylsilsesquioxane) hybrid nanocomposite films

Hybrid nanocomposite films of poly(vinylsilsesquioxane) (PVSSQ) and polyimide (PI) (PI/PVSSQ) were prepared via sol‐gel process from triethoxyvinylsilane (VSSQ) and thermal imidization from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA)‐p‐phenylene diamine (PDA) polyamic acid (BPDA‐PDA PAA). We investigated the microstructure; interfacial interaction; and optical, thermal, dielectric, and mechanical properties of the hybrid films. The phase morphologies and degree of surface roughness were evaluated by scanning electron microscope (SEM) and atomic force microscope (AFM), respectively. It was found that the surface topography was influenced by the composition of PVSSQ. Hydrogen bonding interactions between polyimide (PI) matrix and PVSSQ domains were proved with FT‐IR spectroscopy. The transparency of the hybrid films was found to be dependent on the PVSSQ content. Incorporating of the PVSSQ in the hybrid composites increased the glass transition temperature of PI. Dielectric constants of the hybrid films were in the range of 2.37–3.59. Properties of the PI films were also significantly enhanced by adding 5–30 wt % of PVSSQ. For comparison, we also prepared the hybrid composites of PI and mixtures of VSSQ and tetraethoxysilane (TEOS) and the PI/silica hybrid composite containing 30 wt % of silica obtained from TEOS. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5189–5199, 2004     

Gel–sol transition for soluble polyimide solution

Copolyimides were synthesized in N‐methyl‐2‐pyrrolidone (NMP) to prepare polyimide (PI) solutions with various concentrations, and gels can form in PI/NMP solution with a suitable concentration or at a low temperature. Gel–sol transition in the PI/NMP solution has been investigated through a combination of polarized optical microscope, differential scanning calorimeter measurement, and rheological measurements. According to Winter–Chambon theory, the critical gel point is 12 wt %, and the loss tangent (tan δ) shows frequency independence. Gel–sol transition temperature (T_gel) for the 13 wt % solution is around 65 °C. Below the T_gel, the gel exhibits strong optical planar texture, indicating the formation of a fully anisotropic phase, which has a great importance for the fabrication of PI fibers by gel‐spinning. Dynamic temperature sweep measurements show that the formation of the gel from solution is thermoreversible and is significantly delayed in the cooling process. Under the favorable conditions, the tensile strength and modulus of the fibers derived from the solution are about 0.7 and 12.5 GPa using gel‐spinning method, which is believed to afford broad application potential in preparing high‐performance PI fibers. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 450–459     

Structural and dielectric properties of POSS reinforced polyimide nanocomposites

In this study, a series of [3-(2-aminoethyl)amino]propyl-heptaisobutyl substituted polyhedral oligomeric silsesquioxane (AHIP) containing polyimide (PI) nanocomposites were successfully prepared. Structural, thermal and electrical properties of the polyimide nanocomposites were studied. The properties of AHIP containing polyimides were compared with those of the neat polyimide films. The surface morphology of the prepared AHIP containing polyimides were determined by using Scanning Electron Microscopy (SEM). The hydrophilic/hydrophobic nature of AHIP/polyimide composites were analyzed by measuring their water contact angles. It was found that the addition of AHIP into the polyimide slightly increased the contact angle values. The incorporation of 5% AHIP to the PI matrix decreased the dielectric constant value of pure PI from 8.6 to 11.7, respectively. Furthermore he dielectric permittivity was changed from 8.6 (neat polyimide) to 5.5 (PI3).     

Dynamics in disordered block copolymers and miscible blends composed of poly(vinyl ethylene) and polyisoprene

We investigated the segmental and terminal relaxation dynamics of a well‐characterized disordered diblock copolymer, poly(isoprene‐b‐vinyl ethylene) (PI‐PVE), and miscible blends of polyisoprene (PI)/poly(vinyl ethylene) (PVE), using dielectric and viscoelastic spectroscopies. Generally, the concentration fluctuation (CF) amplitude of a disordered diblock copolymer is smaller than that of the miscible blend, especially in a length scale longer than the size of the whole block chain. To test whether the difference in the CF amplitudes causes the difference in the segmental relaxation spectra, we compared the shape of the dielectric loss curves between PI‐PVE and PI/PVE with the same composition (PI/PVE ratio = 17:83). However, no appreciable difference was observed, indicating that the CF amplitudes in PI‐PVE and PI/PVE are not so different in the length scale of the segmental motions. We also examined the effect of distinct friction coefficients of the PI and PVE chains on the terminal relaxation dynamics by comparisons of the viscoelastic and dielectric normal mode relaxations in PI‐PVE. The former probes the whole chain motion and the latter probes motions of the PI block. Shift factors (a_T) for the viscoelastic and dielectric relaxations were compared. The dielectric normal mode a_T was found to have weaker temperature dependence than the viscoelastic a_T, which indicates that the friction for the PI block chain is lower than the average friction for the PI‐PVE chain. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4084–4094, 2004     

Dielectric spectroscopic analysis of polyvinyl chloride nanocomposites loaded with Fe2O3 nanocrystals

Iron oxide (α‐Fe₂O₃) nanocrystals powder was successfully synthesized via the sol‐gel method. The microstructural examination of the synthesized nanocrystals confirmed the formation of α‐Fe₂O3 (hematite) structure using X‐ray diffraction and Fourier transform infrared. The synthesized nano‐hematite powder with different weight percentage up to 5 wt% was introduced to polyvinyl chloride (PVC) to fabricate PVC/Fe₂O₃ nanocomposites using the solution‐cast technique. The dielectric spectroscopic analysis for the investigated samples has been studied at room temperature and at different temperatures up to 120°C. The real part of the permittivity (ε^′) exhibited a significant dependence on filler concentrations throughout whole temperature range. However, the dependency of both of the loss tangent (tanδ ) and AC conductivity (σ_ac) on filler concentrations is more pronounced at temperatures higher than room temperature. The obtained values of tan δ for the investigated nancomposites referred to the α‐relaxation around 70°C, which is close to glass transition temperature of the investigated PVC. The dependency of the dielectric strength on Fe₂O₃ nanofiller concentration was observed with enhancement in the dielectric strength reach to 20.5% for PVC/0.7 wt% Fe₂O₃ nanocomposite higher than the recorded value for the pristine PVC.     

Preparation and dielectric properties of polyimide/silica nanocomposite films prepared from sol–gel and blending process

Using poly(amic acid) (PAA) as a precursor followed by thermal imidization, the polyimide/silica nanocomposite films were prepared via an improved sol–gel process and a blending process, respectively. FT‐IR, TEM and TGA measurements were used to characterize the structure and properties of the obtained films. The results confirmed that the introduction of silica did not yield negative effects on the conversion of the PAA precursor to the polyimide. With the increase of silica content, the aggregation of silica appeared in the polyimide matrix, and the thermal stability decreased slightly for both kinds of films. The dielectric constant (ε) of both films increased slowly with the increase of the silica concentration. The dielectric constant of the obtained polyimide/silica nanocomposite films displayed good stability within a wide range of temperatures or frequency. Based on modeling relation between ε and silica content, the difference in dielectric properties for two kinds of nanocomposites are discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Synthesis,morphology, and properties of hydroxyl terminated‐POSS/polyimide low‐k nanocomposite films

Polyhedral oligomeric silsequioxane (POSS), having eight hydroxyl groups for the preparation of nanocomposites with polyimide (PI) was synthesized by the direct hydrosilylation of allyl alcohol with octasilsesquioxane (Q₈M₈^H) with platinum divinyltetramethyl disiloxane Pt(dvs) as a catalyst. The structure of allyl alcohol terminated‐POSS (POSS‐OH) was confirmed by FTIR, NMR, and XRD. A high performance, low‐k PI nanocomposite from pyromellitic dianhydride (PMDA)‐4,4'‐oxydianiline (ODA) polyamic acid cured with POSS‐OH was also successfully synthesized. The incorporation of POSS‐OH into PI matrix reduced dielectric constant of PI without loosing mechanical properties. Furthermore, the effects of POSS‐OH on the morphology and properties of the PI/POSS‐OH nanocomposites were investigated using UV–vis, FTIR, XRD, SEM, AFM, transmission electron microscope (TEM), TGA, and contact angle. The homogeneous dispersion of POSS particles was confirmed by SEM, AFM, and TEM. The nanoindentation showed that the modulus increased upon increasing the concentration of POSS‐OH in PI, whereas the hardness did not increase very much with respect to loading of POSS, due to soft‐interphase around POSS molecules in the resulting nanocomposites. Overall results demonstrated the nanometer‐level integration of the polymer and POSS‐OH. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5887–5896, 2008     

Synthesis and properties of bismaleimide‐modified novolak resin/silsesquioxane nanocomposites

Bismaleimide‐modified novolak resin/silsesquioxane (BMI‐PN/SiO_3/2) nanocomposites were prepared by the sol–gel process. The reactions in the sol–gel synthesis were characterized by Fourier transform infrared spectroscopy. It was found by field emission scanning electron microscopy and atomic force microscopy studies that the particle size of the dispersed phase was about 100 nm, and there existed particle aggregates. The proportion of bismaleimide in the BMI‐PN/SiO_3/2 nanocomposites showed an important effect on the thermal properties of the composites, as demonstrated by thermogravimetric analysis and dynamical mechanical analysis. Major improvements in the glass‐transition temperature and the heat resistance of the material were achieved by the introduction of the nanosized SiO_3/2 inorganic phase, and the modulus at high temperatures was improved too. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2599–2606, 2003     

Simultaneous Preparation of PI/POSS Semi‐IPN Nanocomposites

Summary: This investigation presents a simultaneous and convenient approach to produce a high‐performance polyimide with a low dielectric constant by introducing the octa‐acrylated polyhedral oligomeric silsesquioxane (methacrylated‐POSS) into a polyimide matrix to form polyimide semi‐interpenetrating polymer network (semi‐IPN) nanocomposites. The differential scanning calorimetry (DSC) and Fourier‐transform infrared (FT‐IR) results indicate that the self‐curing of methacrylated‐POSS and the imidization of polyamic acid (PAA) occurs simultaneously. The morphology of a semi‐IPN structure of polyimide/POSS‐PI/POSS nanocomposites with POSS nanoparticles embedded inside the matrix is elucidated. The POSS particles are uniform and are aggregated to a size of approximately 50–60 nm inside the polyimide matrix. The interconnected POSS particles are observed at high POSS content. The structure is highly cross‐linked, so the PI/POSS nanocomposites have an enhanced glass transition temperature. The high porosity of the PI/POSS nanocomposites markedly reduces the dielectric constant of PI because of the nanometer‐scale porous structure of POSS.

FT‐IR spectra of the various compounds of A) methacrylate‐POSS before curing, B) methacrylate‐POSS after curing, C) PAA containing 15 wt.‐% POSS, and D) PI/POSS containing 15 wt.‐% POSS.     

Conducting polyaniline-rutile TiO2 nanocomposites for the development of high-k dielectric materials

Inorganic dielectrics encapsulated in an organic matrix are showing excellent promise as novel dielectric materials. In this work, firstly highly organized crystalline nanoparticles of rutile TiO₂ were synthesized by acid hydrolysis of titanium isopropoxide at room temperature. Then we developed a novel dielectric material consisting of highly organized rutile TiO₂/polyaniline (PAni) nanocomposites by in-situ chemical oxidative polymerization. The structural, morphological, conducting, and dielectric properties of the rutile TiO₂/PAni nanoparticles have been evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution-transmission emission microscopy (HR-TEM), four-point probe technique, CV (Capacitance versus Voltage), and Impedance analyzer. The nanocomposites show 70 times higher permittivity compared to rutile nanoparticles and much higher compared to anatase/PAni (ES) nanocomposites at 10 MHz. Large interfacial polarizations, nanostructure, and dopant levels are the key factors for the large dielectric constant of the nanocomposites. The rutile/PAni (ES) nanocomposites might see potential uses in super-capacitors, gate dielectric in transistors, and capacitive-type gas sensors.     

Synthesis of Macroporous PMMA/Silica Nanocomposite Monoliths in Supercritical Carbon Dioxide

Summary: Macroporous monoliths consisting of silica nanoparticles embedded in poly(methyl methacrylate) (PMMA) were synthesized in supercritical CO₂. Well‐dispersed silica particles, pretreated with functional 3‐(trimethoxysilyl)propyl methacrylate (MPS), were to form colloidal PMMA nanocomposites followed by a sol‐gel transition forming interconnected structures resulting in micron‐sized pores with specific areas between 1 and 7 m² · g⁻¹. SEM and TEM results revealed uniform morphological characteristics of the composite materials and good dispersions of the silica nanoparticles.

SEM micrograph of PMMA/Silica nanocomposites forming interconnected macroporous monolith. The average size of the silica particles is 50 nm.     

Effect of preparation of titania sol on the structure and properties of acrylic resin/titania hybrid materials

Acrylic resin/titania organic–inorganic hybrid materials were prepared by mixing titania sol produced by the sol–gel process with synthesized thermoplastic acrylic resins. The effects of the amounts of water and acid on hydrolysis and condensation of the sol–gel precursor (titanium n‐butoxide) were characterized by nuclear magnetic resonance, and their corresponding influences on the structure and properties of the hybrid films were investigated by small‐angle X‐ray scattering (SAXS), atomic force microscopy, dynamical mechanical analysis, an Instron testing machine, and ultraviolet–visible spectroscopy. SAXS indicated an open structure and nanoscale size for the titania phase of the hybrids. Higher titania content and a greater amount of water or acid in the sol–gel process resulted in titania domains that were larger size and had a more compact structure. The mechanical and UV‐shielding properties of the organic polymer obviously were improved with titania embedded. As the amount of water or acid in the sol–gel process increased, integrative mechanical properties decreased, with the amount of water having a greater impact than the amount of acid on the structure and optical properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3682–3694, 2004     

Molecular dynamics in nanostructured polyimide–silica hybrid materials and their thermal stability

Molecular motion and thermal stability in two series of nanophase‐separated polyimide–silica (PI–SiO₂) hybrid materials with chemically bound components were studied. The hybrids were synthesized from p‐aminophenyltrimethoxysilane‐terminated poly(amic acid)s as PI precursors and tetramethoxysilane as a silica precursor via a sol–gel process. The hybrids differed in their PI chemical structure and chain length (number‐average molecular weight = 5.000, 7.500, or 10.000) and in their SiO₂ content, which ranged from 0 to 50 wt %. Differential scanning calorimetry, laser‐interferometric creep rate spectroscopy, and thermally stimulated depolarization current techniques were used for studying the dynamics from 100 to 650 K and from 10^?3 to 10^?2 Hz. Comparative thermogravimetric measurements were also carried out from 300 to 900 K. Silica nano‐ or submicrodomains that formed affected PI dynamics in two opposite directions. Because of the loosening of the molecular packing of PI chains confined to nanometer‐scale spaces between silica constraints, an enhancement of small‐scale motion, mostly at temperatures below the β‐relaxation region, occurred. However, a partial or total suppression of segmental motion could be observed above the β‐relaxation temperature, drastically so for the shortest PI chains at elevated silica contents and within or close to the glass‐transition range, because of the covalent anchoring of chain ends to silica domains. Large changes in thermal stability, including a 2.5‐fold increase in the apparent activation energy of degradation, were observed in the hybrids studied. A greater than 100 °C rise in long‐term thermal stability could be predicted for some hybrids with respect to pure PI. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 1056–1069, 2002     

Effect of Dielectric Constant of Solvents on the Particle Size and Bandgap of La/SnO2‐TiO2 Nanoparticles and Their Catalytic Properties

Lanthanum (La) supported on tin oxide‐titanium oxide (SnO₂‐TiO₂ ) nanoparticles were prepared by a sol–gel method followed by a hydrothermal method. Effect of different solvents (ethyl acetate, benzyl alcohol, ethylene glycol) on the particle size and catalytic activity was investigated. The nanomaterial was characterized by transmission electron microscopy, powder X‐ray diffraction, scanning electron microscopy, fourier transform infrared spectroscopy, and energy dispersive X‐ray. The catalytic and optical properties were studied using solid‐phase spectrophotometry and ultraviolet–visible spectroscopy, respectively. Gas chromatography‐mass spectrometry (GC‐MS) was used to detect the intermediates during the catalytic degradation of methylene blue. It was observed that with decrease in the dielectric constant (ε) of the solvent, the bandgap and particle size decrease and catalytic efficiency increases. Hence, the highest catalytic activity was observed with the solvent having the least dielectric constant.     

Polyimide/polyoxometalate copolymer thin films: synthesis,thermal and dielectric properties

A mono‐lancunary keggin‐type decatungstosilicate (SiW₁₁) polyoxometalate (POM) modified by γ‐aminopropyltriethoxysilane (KH550) was incorporated into polyimide (PI) through copolymerization. Nuclear magnetic resonance (NMR), fourier transition infrared spectroscopy (FTIR), and wide angle X‐ray diffraction (WAXD) were used to characterize the structure and composition of the polyoxometalate–organosilane hybrid (SiW₁₁KH550) and PI/SiW₁₁KH550 copolymers. The differential scanning calorimetry (DSC) studies indicate that the glass transition temperature (T_g) of PI/SiW₁₁KH550 copolymers increases from 330°C (for neat PI) to 409°C (for the copolymer sample with 10 wt% of SiW₁₁KH550). Dielectric measurement showed that both the dielectric constant and the dielectric loss for the copolymer thin films decreased with the increase in SiW₁₁KH550 content, and the dielectric constant and dielectric loss values decreased to 2.1 and 3.54 × 10^?3, respectively, for the copolymer sample with 10 wt% of SiW₁₁KH550. The incorporation of SiW₁₁KH550 into polymer matrices is a promising approach to prepare PI films with a low dielectric constant and low dielectric loss. Copyright © 2009 John Wiley & Sons, Ltd.