Preparation and characterization of poly(ϵ‐caprolactone‐co‐p‐dioxanone)–poly(ethylene glycol)–poly(ϵ‐caprolactone‐co‐p‐dioxanone)/bioactive inorganic particle nanocomposites

With an aim to develop injectable hydrogel with improved solution stability and enhanced bone repair function, thermogelling poly(ε‐caprolactone‐co‐p‐dioxanone)‐poly(ethylene glycol)‐poly(ε‐caprolactone–co‐p‐dioxanone) (PECP)/bioactive inorganic particle nanocomposites were successfully prepared by blending the triblock copolymer (PECP) with nano‐hydroxyapatite (n‐HA) or nano‐calcium carbonate (n‐CaCO₃). The hydrogel nanocomposites underwent clear sol–gel transitions with increasing temperature from 0 to 50°C. The obtained hydrogel nanocomposites were investigated by ¹H NMR, FT‐IR, TEM, and DSC. It was found that the incorporation of inorganic nanoparticles into PECP matrix would lead to the critical gelation temperature (CGT) shifting to lower values compared with the pure PECP hydrogel. The CGT of the hydrogel nanocomposites could be effectively controlled by adjusting PECP concentration or the content of inorganic nanoparticles. The SEM results showed that the interconnected porous structures of hydrogel nanocomposites were potentially useful as injectable scaffolds. In addition, due to the relatively low crystallinity of PECP triblock copolymer, the aqueous solutions of the nanocomposites could be stored at low temperature (5°C) without crystallization for several days, which would facilitate the practical applications. The PECP/bioactive inorganic particle hydrogel nanocomposites are expected to be promising injectable tissue engineering materials for bone repair applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of poly(glycerol sebacate)/cellulose nanocrystals elastomeric composites

Poly(glycerol sebacate) (PGS) is one of the new elastomers used for soft tissue engineering, while improving its limited mechanical strength is the biggest challenge. In this work, a novel biodegradable elastomer composite PGS/cellulose nanocrystals (CNCs) was prepared by solution‐casting method and the mechanical properties, sol–gel contents, crosslink density, and hydrophilic performance were characterized. The thermal and degradation properties of composites were also investigated. Results show that the addition of CNCs into PGS resulted a significant improvement in tensile strength and modulus, as well as the crosslink density and the hydrophilicity of PGS. When the CNCs loading reached 4 wt %, the tensile strength and modulus of the composite reached 1.5 MPa and 1.9 MPa, respectively, resulting 204% and 158% increase compared to the pure PGS. Prolonging the curing time also improved the strength of both the neat PGS and PGS/CNCs composites according to the association and shift of hydroxy peaks around 3480 cm^?1. DSC results indicate that the addition of CNCs improved both the crystallization capacity and moving capability of PGS molecular chain. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42196.     

Preparation and characterization of electrospun PLA/nanocrystalline cellulose‐based composites

Biodegradable nanocomposites of Nanocrystalline Cellulose (NCC) and electrospun poly‐(lactic acid) were prepared via a new mixing technique. Dispersion of hydrophilic NCC in hydrophobic PLA was improved through aqueous mixing and freeze drying of perfectly suspended NCC with PLA nanofibers. Freeze drying produced aerogels with good mechanical integrity. The aerogels were further processed via hot pressing. Resulting composites displayed an improvement in mechanical properties, which was greatest at temperatures below the glass transition temperature of PLA. The optimum compositions were found to be in the 0.5–3% NCC (by weight) range. Experiments performed also showed that due to electrospinning, the crystallinity of the PLA slightly increased and this is accompanied by a decrease in its glass transition temperature. Furthermore, adding NCC to the electrospun PLA matrix did not alter the crystallinity of the final composite. The composites investigated proved their potential to be used in packaging and tissue engineering applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3345–3354, 2013     

Thermal properties and crystallinity of PCL/PBSA/cellulose nanocrystals grafted with PCL chains

Bionanocomposite films of poly(?‐caprolactone) (PCL) and poly(butilene succinate‐co ‐adipate) (PBSA) blends with cellulose nanocrystals (CNW) grafted with PCL chains (CNW‐g ‐PCL) were prepared by solution casting and their thermal properties and crystallinity were studied. The CNW surface was modified with PCL chains by grafting “from” approaches, in an effort to improve their compatibility with the polymer blends. The grafting efficiency was evidenced by FTIR and TGA analysis. The acicular morphology of CNW‐g ‐PCL was characterized by SEM. The TGA results showed an increase in the thermal stability of the CNW grafted with PCL chains. The PCL/PBSA blends showed higher thermal stability in comparison with the neat polymers and PCL/PBSA/CNW‐g ‐PCL bionanocomposites. DSC results showed the CNW‐g ‐PCL act as a nucleating agent in the bionanocomposites. Additionally, a better interaction of the CNW‐g ‐PCL in the blends of 30/70 composition in comparison with the blends of 50/50 composition was characterized. The results obtained for aforementioned films prepared by solution casting encourage the production of such bionanocomposites by melt compounding (extrusion), aiming the achievement of new bionanocomposites materials with improved thermal and mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44493.     

Preparation and characterization of tough and highly resilient nanocomposite hydrogels reinforced by surface-grafted cellulose nanocrystals

Despite many strong and tough hydrogels have been fabricated according to the energy dissipating mechanism, they usually lack high resilience due to the presence of large hysteresis. Herein, poly (N-vinylpyrrolidone) grafted cellulose nanocrystal (CNC-g-PVP) was used as special multifunctional physical crosslinkers to fabricate tough and highly resilient nanocomposite hydrogels. CNC-g-PVP with varying loading was incorporated into chemically crosslinked polyacrylamide (PAM) networks by in-situ radical polymerization to give PAM/CNC-g-PVP nanocomposite hydrogels. Robust cooperative hydrogen bonds existed between the surface-grafted PVP chains and the PAM matrix, which could rupture to dissipate energy upon deformation and recover instantly on the removal of stress. This unique energy dissipating mechanism led to excellent mechanical performance of the hydrogels. Their tensile elastic modulus, toughness, and compressive strength are 1.4–1.8, 2.1–3.0, and 1.44–2.73 times of pure PAM hydrogel, respectively. Moreover, the hydrogels exhibit low hysteresis, high resilience (ca. 97%) under cyclic tensile loading-unloading and good recovery of hysteresis (ca. 90%) under cyclic compressive loading-unloading.     

Preparation and characterization of Silicalite‐1/PDMS surface sieving pervaporation membrane for separation of ethanol/water mixture

To improve the pervaporation performance of Silicalite‐1/PDMS composite membrane by adding a small amount of Silicalite‐1 zeolite, novel Silicalite‐1/PDMS surface sieving membranes (SSMs) were prepared by attaching Silicalite‐1 particles on the PDMS membrane surface. The obtained membranes and traditional mixed‐matrix membranes (MMMs) were characterized by SEM, XRD, TGA, FT‐IR, and pervaporation separation of ethanol–water mixture. Effects of Silicalite‐1 particles content, feed temperatures, and feed compositions on the separation performance were discussed. From the cross‐section view SEM images of SSMs, a two‐layer structure was observed. The thickness of the Silicalite‐1 layer was about 300 nm to 2 μm. The TGA analysis indicates that the zeolite concentration in 3 wt % SSM is lower than 10 wt % MMMs. In the ethanol/water pervaporation experiment, the separation factor of Silicalite‐1/PDMS SSMs increased considerably compared with pure PDMS membrane. When the suspensions concentrations of Silicalite‐1 particles reached 3 wt %, the separation factor was about 217% increase over pure PDMS membrane and 52.9% increase over 10 wt % Silicalite‐1/PDMS MMMs. As the ethanol concentration in the feed increases, the separation factor of SSMs increases, whereas permeation flux decreases. At the same time, with increasing operating temperature, the permeation flux of SSMs increased. The stability of SSMs at high temperature is better than the traditional MMMs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42460.     

Melt extruded nanocomposites of polybutylene adipate‐co‐terephthalate (PBAT) with phenylbutyl isocyanate modified cellulose nanocrystals

Traditional commodity polymers are widely used in several disposable or short‐life items and take hundreds of years to decompose in nature. These polymers could be replaced in several uses by biodegradable polymers, like polybutylene adipate‐co‐terephthalate (PBAT) studied in this work. For this, nonetheless, it is necessary to improve some of the PBAT properties, like mechanical resistance and barrier properties. In this work, cellulose nanocrystals (CNC) were incorporated in PBAT with this intention, through melt extrusion. Aiming to avoid CNC aggregation during the drying and extrusion process, a CNC chemical modification with phenylbutyl isocyanate was done. It was possible to obtain PBAT‐CNC melt extruded composites with an elastic modulus 55% higher and water vapor permeability 63% lower than the values of the pure polymer, without compromising PBAT biodegradation. Therefore, the composites prepared with these enhanced properties have great potential as substitutes for traditional commodity polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43678.     

Preparation and properties of hydrophobic poly(vinylidene fluoride)–SiO2 mixed matrix membranes for dissolved oxygen removal from water

The application of the membrane method for removing dissolved oxygen (DO) from water on the laboratory scale was studied. Flat mixed matrix membranes were composed of poly(vinylidene fluoride) (PVDF) and hydrophobic nanosilica particles, which were used to improve the DO removal process. The SiO₂ particles were modified by a silane coupling agent and examined by Fourier transform infrared spectroscopy. It was shown that the surface of the SiO₂ particles was bonded to hydrophobic long‐chain alkane groups through chemical bonding. The effects of adding SiO₂ particles on the membrane properties and morphology were examined. The results show that the porosity and pore size of the membrane were affected by the introduction of SiO₂ particles, and the cross‐sectional morphology of the PVDF composite membranes changed from fingerlike macrovoids to a spongelike structure. The membrane performance of DO removal was evaluated through the membrane unit by a vacuum degassing process. It was found that the SiO₂/PVDF hybrid membranes effectively improved the oxygen removal efficiency compared with the original PVDF membranes. The maximum permeation flux was obtained when the loading amount was 2.5 wt %. The effect of the downstream vacuum level was also investigated. The experimental results show that the SiO₂/PVDF hybrid membranes had superior performances and could be an alternative membrane for removing DO from water. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40430.     

Influence of the polymorphism of cellulose on the formation of nanocrystals and their application in chitosan/nanocellulose composites

In this study, we evaluated the physicochemical properties of the chitosan/nanocellulose composites. Wide‐angle X‐ray scattering was applied to define the supermolecular structure of the materials, the laser diffracting technique was used to characterize the particle sizes, and scanning electron microscopy was used to evaluate the morphologies of the samples. The tensile properties of the composite films were also determined. Cellulose pulp was mercerized with 16% sodium hydroxide to give only cellulose II. Cellulose I and cellulose II were subsequently hydrolyzed with 64% sulfuric acid. As a result, nanocellulose I (NCC I) from cellulose I and nanocellulose II (NCC II) from cellulose II were produced. The mercerization of cellulose pulp contributed to a significant particle size reduction; more than 50% of the particles of the NCC II sample and only 36% of the particles of the NCC I sample were smaller than 100 nm. Chitosan composite films containing 5, 10, and 20% w/w of nanocelluloses were prepared by a solvent casting method. This was the first study investigating the influence of the crystallographic forms of cellulose on the formation of nanocrystals. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42864.     

Thermo‐mechanical behavior of poly(butylene terephthalate)/silica nanocomposites

In this work, experimental results about poly(butylene terephthalate) (PBT) based nanocomposites filled with various amounts of silica nanoparticles (NPs) are reported. Two different types of filler are used: silica gel NPs, produced through the Stöber method, and a commercial fumed silica, both coated by a PBT shell. Melt‐mixed samples have been thoroughly investigated by scanning and transmission electron microscopy, infrared Fourier transform spectroscopy (FTIR), thermal gravimetric analysis, differential scanning calorimetry, wide and small angle X‐ray diffraction, and dynamic mechanical analysis. A fine and very good dispersion of NPs into the polymeric matrix is revealed through the morphological analysis when Stöber NPs were used as filler with respect to systems including commercial fumed silica particles. This evidence, combined with matrix–filler interactions revealed by FTIR spectroscopy, justifies the enhancement of both storage modulus and glass transition temperature of the former samples in comparison with reference pristine PBT. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46006.     

Evaluation of mechanical properties and physical interactions of a ternary blend of poly(ethylene‐co‐octene)/poly(ethylene‐co‐vinyl acetate)/poly(vinyl chloride) in the molten state

In this work, ethylene‐co‐vinyl acetate (EVA), poly(ethylene‐co‐octene) (POE), and poly(vinyl chloride) (PVC) blends were processed in a molten state process using a corotating twin‐screw extruder to assess both the balance of mechanical properties and physical interactions in the melt state. Tensile measurements, scanning electron microscopy, and oscillatory rheometry were performed. By means of flow curves, the parameters of the power law as well as the distribution of relaxation times were assessed with the aid of a nonlinear regularization method. The mechanical properties for the EVA‐POE blend approximated the values for POE, while inclusion of PVC shifted the modulus values to those of neat EVA. The rise in modulus was corroborated by the PVC phase dispersion as solid particles that act as a reinforcement for the ternary blend. The rheological properties in the molten state show that the POE does not present molecular entanglement effects and so tends both to diminish the EVA mechanical properties and increase the fluidity of the blend. However, the addition of PVC both restored the EVA typical pseudoplastic feature and promoted the increase in the viscosity and the mechanical properties of the ternary blend. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and characterization of poly(vinyl chloride)/polystyrene/poly(ethylene glycol) hollow‐fiber ultrafiltration membranes

Hollow‐fiber ultrafiltration (UF) membranes were prepared from blends of poly(vinyl chloride) (PVC) and polystyrene (PS) with a dry/wet phase inversion method. Poly(ethylene glycol) (PEG) and N,N‐dimethylacetamide were used as the additive and solvent, respectively. The effects of the PEG concentration in the dope solution as an additive on the cross sections and inner and outer surface morphologies, permeability, and separation performance of the hollow fibers were examined. The mean pore size, pore size distribution, and mean roughness of both the inner and outer surfaces of the produced hollow fibers were determined by atomic force microscopy. Also, the mechanical properties of the hollow‐fiber membranes were investigated. UF experiments were conducted with aqueous solutions of poly(vinyl pyrrolidone) (PVP; K‐90, M_w = 360 kDa). From the results, we found that the PVC/PS hollow‐fiber membranes had two layers with a fingerlike structure. These two layers were changed from a wide and long to a thin and short morphology with increasing PEG concentration. A novel and until now undescribed shape of the nodules in the outer surfaces, which was denoted as a sea‐waves shape, was observed. The outer and inner pore sizes both increased with increasing PEG concentration. The water permeation flux of the hollow fibers increased from 104 to 367 L m^?2 h^?1 bar^?1) at higher PEG concentrations. The PVP rejection reached the highest value at a PEG concentration of 4 wt %, whereas at higher values (from 4 to 9 wt %), the rejection decreased. The same trend was found also for the tensile stress at break, Young's modulus, and elongation at break of the hollow fibers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 989‐1004, 2013     

Surface‐modified MgO nanoparticle enhances the mechanical and direct‐current electrical characteristics of polypropylene/polyolefin elastomer nanodielectrics

Polypropylene (PP)/polyolefin elastomer (POE) blends and MgO/PP/POE nanocomposites were fabricated by melt blending. The morphology, mechanical, and electrical properties of the nanocomposites were investigated. Scanning electron microscopy showed that the surface‐modified MgO nanoparticles were well dispersed in the polymer matrix at low loadings of less than 3 phr. X‐ray diffraction demonstrated that the crystalline phases of PP in the composites were changed and that the β phase significantly increased. An examination of the electrical properties revealed that the direct‐current (dc) electric breakdown strength and space‐charge suppression effect were remarkably improved by the introduction of the surface‐modified MgO nanoparticles. In addition, obvious enhancements in the tensile modulus and strength were obtained as a result of the synergistic toughening of the POE and MgO nanoparticles. Thus, MgO/PP/POE nanocomposites with enhanced mechanical and electrical properties have great potential to be used as recyclable insulation materials for high‐voltage dc cables with large transmission capacities and high operating temperatures. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 132, 42863.     

Poly(butylene succinate)/layered double hydroxide bionanocomposites: Relationships between chemical structure of LDH anion,delamination strategy,and final properties

A series of poly(butylene succinate) (PBS) containing organo‐modified layered double hydroxide (LDH) are prepared by melt compounding and by in situ polymerization of succinic ester and 1,4‐butanediol. Various LDHs intercalated with renewable organic anions are used. More specifically, lauryl sulfate, stearate, succinate, adipate, sebacate, citrate, and ricinoleate ions are used as LDHs organo‐modifiers. The thermal, rheological, and dynamic mechanical properties of the samples are investigated. The results reveal a general mechanical reinforcement imparted by the clays. Significant changes are observed for the in situ polymerized nanocomposites, especially for LDH stearate which improves the properties of PBS nanostructure, whereas very few differences are observed for the other samples. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1931–1940, 2013     

Crystallization kinetics,morphology, and hydrolytic degradation of novel bio‐based poly(lactic acid)/crystalline silk nano‐discs nanobiocomposites

In this work, novel biodegradable crystalline silk nano‐discs (CSNs) having a disc‐like morphology have been utilized for fabrication of poly(lactic acid) (PLA) nanocomposites by melt‐extrusion. The main focus is to investigate the effect of CSN on isothermal melt crystallization kinetics, spherulitic growth rates, morphology, and hydrolytic degradation of PLA. Spherulitic morphology and growth rates are examined over a wide range of crystallization temperatures (90–120 °C). With incorporation of CSN, the isothermal crystallization kinetics of PLA/CSN increases, however, the crystallization mechanism remains unaltered. The apparent activation energy and surface energy barrier for crystallization process decreases upon addition of CSNs. At lower isothermal crystallization temperatures (T_c) viz. (90–100 °C), reduced growth rates of PLA spherulites is observed. Both PLA and PLA/CSN exhibit highest crystallization rates at around ～107 °C. The hydrolytic degradation rates calculated from molecular weight reduction shows that PLA/CSN nanocomposites' degradation rates are lower as compared to PLA in acidic, neutral, and alkaline media at pH = 2, 7, and 12, respectively, due to hydrophobic nature of CSN. Scanning electron microscopy study demonstrated the surface erosion mechanism of hydrolytic degradation of PLA and PLA/CSN nanocomposites. This work provides valuable insight for the application and reclamation of PLA/CSN bionanocomposites in moist and wet working environments. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46590.     

Morphological,thermal, and mechanical properties of poly(ε‐caprolactone)/poly(ε‐caprolactone)‐grafted‐cellulose nanocrystals mats produced by electrospinning

Electrospun nanocomposites of poly(ε‐caprolactone) (PCL) incorporated with PCL‐grafted cellulose nanocrystals (PCL‐g‐CNC) were produced. PCL chains were grafted from cellulose nanocrystals (CNC) surface by ring‐opening polymerization. Grafting was confirmed by infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA). The resulting PCL‐g‐CNC were then incorporated into a PCL matrix at various loadings. Homogeneous nanofibers with average diameter decreasing with the addition of PCL‐g‐CNC were observed by scanning electron microscopy (SEM). PCL‐g‐CNC domains incorporated into the PCL matrix were visualized by transmission electron microscopy (TEM). Thermal and mechanical properties of the mats were analyzed by differential scanning calorimetry (DSC), TGA and dynamic mechanical analysis (DMA). The addition of PCL‐g‐CNC into the PCL matrix caused changes in the thermal behavior and crystallinity of the electrospun fibers. Significant improvements in Young's modulus and in strain at break with increasing PCL‐g‐CNC loadings were found. These results highlighted the great potential of cellulose nanocrystals as a reinforcement phase in electrospun PCL mats, which can be used as biomedical materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43445.     

Preparation and characterization of hydrophilic and antifouling poly(ether sulfone) ultrafiltration membranes modified with Zn–Al layered double hydroxides

Zn–Al layered double hydroxide (LDH)‐entrapped poly(ether sulfone) (PES) ultrafiltration membranes with four different weight percentages, 0.5, 1.0, 2.0, and 3.0%, were prepared by a phase‐inversion method. Characterization by scanning electron microscopy, atomic force microscopy and contact angle (CA), equilibrium water content, porosity, average pore size, mechanical strength, and ζ potential measurement were used to evaluate the morphological structure and physical and chemical properties of membranes. Static protein adsorption, filtration, and rejection experiments were conducted to study the antifouling properties, water permeability, and removal ability of the modified membranes. The results show that significant change occurred in the membrane morphology and that better hydrophilicity, water permeability, and antifouling ability were also achieved for the PES/LDH membranes when a proper amount of LDH was used. For example, the CA value decreased from 66.60 to 50.21°, and the pure water flux increased from 80.21 to 119.10 L m^?2 h^?1 bar^?1 when the LDH loading was increased from 0 to 2.0 wt %. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43988.     

Poly(vinylidene fluoride‐co‐hexafluoropropylene) nanocomposites incorporating cellulose nanocrystals with potential applications in lithium ion batteries

Cellulose nanocrystals (CNCs) have received considerable attention recently because CNCs can be produced from renewable materials such as straw, wood, cotton, and sea animals (tunicates). CNCs are one of the stiffest organic materials, with an estimated tensile modulus (E) of 80–160 GPa depending on the starting material. In addition, composites incorporating CNCs have been fabricated from a variety of polymer matrices and CNCs have been shown to increase the E significantly and to a lesser extent the tensile strength (TS). A copolymer of poly(vinylidene fluoride) (PVDF), PVDF‐co‐hexafluoropropylene) (PVDFHFP), has received interest over the years in the area of lithium ion battery separator technology. However, the mechanical properties of neat PVDFHFP do not meet the necessary requirements for commercial separators, especially the low E. In this work, novel PVDHFHFP/CNC nanocomposite films were fabricated and characterized. It was found that incorporation of CNCs improves the E and TS. The improvement in mechanical properties of PVDFHFP upon addition of CNCs makes PVDFHFP a more suitable candidate for polymer separators in lithium ion batteries. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Temperature dependent dielectric properties of self‐standing and flexible poly(vinylidene fluoride) films infused with Er3+ doped GeO2 and SiO2 nanoparticles

The synthesis of Er³⁺@GeO₂ and Er³⁺@SiO₂ nanoparticle impregnated self‐standing poly(vinylidene fluoride) films by a facile solution casting technique has been reported. The prepared films were thoroughly characterized using X‐ray diffraction technique, field emission scanning electron microscopy, and transmission electron microscopy. The optical properties were evaluated using UV–Vis spectroscopy. Detailed study on the temperature dependent dielectric properties of the composite films with different Er³⁺ content were also investigated to establish the electrical properties of the same, which revealed the presence of different relaxation processes, namely, and ρ. Due to the smaller size, Er³⁺@SiO₂ was found to disperse better in the PVDF matrix than Er³⁺@GeO₂, which resulted in higher dielectric constant of the former at 300 K. At higher temperature (403 K), the behavior was reversed due to the formation of larger sized low mobility complexes. An investigation on ac conductivity proved the conduction mechanism for neat as well as composite PVDF films to follow the Correlated Barrier Hopping model. The loading of Er³⁺@GeO₂ and Er³⁺@SiO₂ nanoparticles in the PVDF matrix significantly enhances the dielectric properties without losing the flexibility of the composite films. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44016.     

High‐k dielectric composites of poly(2‐cyanoethyl vinyl ether) and barium titanate for flexible electronics

High‐k dielectric composite material for electronic applications was obtained by mixing a polymer with high dielectric constant, poly(2‐cyanoethyl vinyl ether) (CEPVA), and highly crystalline barium titanate (BT). Barium titanate nanoparticles of a size in the range 40–90 nm were prepared by the solvothermal method. By optimizing the reaction conditions, the formation of carbonate impurities and the agglomeration of formed nanoparticles were significantly reduced compared to state‐of‐the‐art procedures. Dielectric spectroscopy was measured in the range of 0.01 Hz to 10 MHz and showed the dielectric constant to be ?′ ～ 35–40 with only 30 vol % content of BT in the composite. Extrapolating to 100% BT nanoparticle concentration and using the Lichtenecker model, the dielectric constant ?′ = 365 ± 27 at 10 kHz was obtained. The relaxation and electrical properties were investigated in depth, and a new relaxation phenomenon was revealed. CEPVA/BT composite is considered suitable for electronic applications, in which high ?′ together with a good mechanical flexibility are required, such as organic field effect transistors. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45236.