Dielectric and thermal studies of segmental dynamics in silica/PDMS and silica/titania/PDMS nanocomposites

Effects of silica and silica/titania nanoparticles on glass transition and segmental dynamics of poly(dimethylsiloxane) (PDMS) were studied for composites of a core–shell type using differential scanning calorimetry, thermally stimulated depolarization current, and dielectric relaxation spectroscopy techniques. Strong interactions between the filler and the polymer suppress crystallinity (T_c, X_c) and affect significantly the evolution of the glass transition in the nanocomposites. The segmental relaxation associated with the glass transition consists of three contributions, arising, in the order of decreasing mobility, from the bulk (unaffected) amorphous polymer fraction (α relaxation), from polymer chains restricted between condensed crystal regions (α_c relaxation), and from the semi‐bound polymers in an interfacial layer with strongly reduced mobility due to interactions with surface hydroxyls of silica and silica/titania nanoparticles (α′ relaxation). The evolution of surface affected CH₃ groups, as well as the degree of interaction of PDMS molecules with surface hydroxyl groups as a function of treatment temperature, was assessed by Fourier transform infrared spectroscopy, thermogravimetry and differential thermal analysis. The effectiveness of silica/PDMS and silica/titania/PDMS nanocomposites as hydrophobic coatings was investigated by static contact angle measurements. It was shown that the presence of titania nanoparticles and adsorbed PDMS promotes the hydrophobic properties of the PDMS coating after treatment in the 80–650°C range. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41154.     

Effects of amorphous silica nanoparticles and polymer blend compositions on the structural,thermal and dielectric properties of PEO–PMMA blend based polymer nanocomposites

The polymer nanocomposite (PNC) films consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend matrices dispersed with nanoparticles of amorphous silica (SiO₂) have been prepared by solution-cast method followed by melt-press technique. Effects of SiO₂ concentration (x?=?0, 1, 3 and 5 wt%) and PEO–PMMA blend compositional ratios (PEO:PMMA?=?75:25, 50:50, and 25:75 wt%) on the surface morphology, crystalline phase, polymer-polymer and polymer-nanoparticle interactions, melting phase transition temperature, dielectric permittivity, electrical conductivity, electric modulus and the impedance properties of the PNC films have been investigated. The crystalline phase of the PNC films decreases with the increase of PMMA contents which also vary anomalously with the increase of SiO₂ concentration in the films. The melting phase transition temperature and polymer-nanoparticle interactions significantly change with the variation in the compositional ratio of the blend polymers in the PNC films. It is observed that the effect of SiO₂ on the dielectric and electrical properties of these PNCs vary greatly with change in the compositional ratio of PEO and PMMA in the blends. The dielectric relaxation process of these films confirm that the polymers cooperative chain segmental dynamics becomes significantly slow when merely 1 wt% SiO₂ nanoparticles are dispersed in the polymer blend matrix.     

Structural and dielectric studies of amorphous and semicrystalline polymers blend‐based nanocomposite electrolytes

The solid polymeric nanocomposite electrolyte (SPNE) films based on the blend of amorphous poly(methyl methacrylate) (PMMA) and semicrystalline poly(ethylene oxide) (PEO) (PMMA:PEO = 80:20 wt %) doped with lithium perchlorate (LiClO₄) salt and montmorillonite (MMT) clay nanofiller were prepared by classical solution cast, ultrasonic assisted solution cast and ultrasonication along with microwave irradiated solution cast followed by melt‐pressing methods. The X‐ray diffraction study of these electrolytes revealed the amorphous behavior with intercalated MMT structures. The suppressed crystallinity of PEO in the blend electrolyte complexes confirmed the existence of single discrete PEO chains confined within the PMMA domains. The dielectric relaxation spectroscopy of these materials was performed over the frequency range 20 Hz to 1 MHz, at ambient temperature. The presence of a singular relaxation peak in the loss tangent and electric modulus spectra of these electrolytes confirms a coupled cooperative chain segmental dynamics of the blend polymer owing to their miscible amorphous morphology. The behavior of transient complexes formed between the polymers functional groups, lithium cations and the intercalated MMT nanoplatelets was explored. The ambient temperature ionic conductivity of these electrolytes depends on the structural dynamics and the sample preparation methods. It is revealed that the presence of PEO in the PMMA matrix mainly governs the structural, dielectric, and ionic properties of these SPNE films. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41311.     

Comparative studies on effects of silica and titania nanoparticles on crystallization and complex segmental dynamics in poly(dimethylsiloxane)

Effects of in situ synthesized silica and titania nanoparticles, 5 and 20-40 nm in diameter, respectively, on glass transition and segmental dynamics of poly(dimethylsiloxane) networks were studied by employing differential scanning calorimetry, thermally stimulated depolarization currents and broadband dielectric relaxation spectroscopy techniques. Strong interactions between the well dispersed fillers and the polymer suppress crystallinity and affect significantly the evolution of the glass transition in the nanocomposites. Next to the α relaxation associated with the glass transition of the bulk amorphous polymer fraction, two more segmental relaxations were recorded, originating from polymer chains restricted between condensed crystal regions (α_c-relaxation) and the semi-bound polymer in an interfacial layer with strongly reduced mobility due to interactions with hydroxyls on the nanoparticle surface (α′ relaxation), respectively. Interactions with the polymer were found to be stronger in the case of titania than silica, leading to an estimated interaction length of around 2 nm for silica and at least double for titania nanocomposites.     

Effects of blending on the molecular dynamics of highly interacting binary polymer blends of poly(methyl methacrylate) and poly[styrene‐co‐(maleic anhydride)]

The molecular dynamics and miscibility of highly interacting binary polymer blends of poly(methyl methacrylate) (PMMA) and poly[styrene‐co‐(maleic anhydride)] random copolymer with 8 wt% maleic anhydride content (SMA) were investigated as a function of composition over a wide range of frequency (10^?2–10⁶ Hz) at different constant temperatures (30–160 °C). Only one common glass relaxation process (α‐process) was detected for all measured blends, and its dynamics and broadness were found to be composition dependent. The existence of only one common α‐relaxation process located at a temperature range between those of the pure polymer components indicated the miscibility of the two polymer components over the entire range of composition. The miscibility was also confirmed by measuring the glass transition temperatures of the blends, T_g, using differential scanning calorimetry. The composition dependence of T_g of the blends showed a positive deviation from the linear mixing rule and well described by the Gordon–Taylor–Kwei equation. The relaxation spectrum of the blends was resolved into α‐ and β‐relaxation processes using the Havriliake–Negami (HN) equation and ionic conductivity. The dielectric relaxation parameters obtained from HN analysis, such as broadness of relaxation processes, maximum frequency, f_max, and dielectric strength, Δ? (for the α‐ and β‐relaxation processes), were found to be blend composition dependent. The kinetics of the α‐relaxation process of the blends were well described by the Meander model, while an Arrhenius‐type equation was used to evaluate the molecular dynamics of the β‐relaxation process. Blending of PMMA and SMA was found to have a considerable effect on the kinetics and broadness of the β‐relaxation process of PMMA, indicating that the strong interaction and miscibility between the two polymer components could effectively change the local environment of each component in the blend. © 2013 Society of Chemical Industry     

Organic base‐catalyzed sol–gel route to prepare PMMA–silica hybrid materials

A series of sol–gel‐derived organic–inorganic hybrid materials that comprise organic poly(methyl methacrylate) (PMMA) and inorganic silica (SiO₂) was successfully prepared using aniline as an organic base catalyst to catalyze the sol–gel reactions of tetraethylorthosilicate (TEOS). Aniline was adopted not only as a catalyst but also as a dispersing agent during the preparation of the hybrid materials. The as‐prepared hybrid materials were then characterized using transmission electron microscopy, SEM/energy dispersive X‐ray spectroscopy and Fourier transform infrared spectroscopy. The characteristic temperatures (including T_d and T_g) of the hybrid materials slightly exceeded those of neat PMMA, as revealed from thermogravimetric analysis and differential scanning calorimetry evaluations. Studies of the protection against corrosion demonstrated that the hybrid coatings all improved the protection performance on cold‐rolled steel coupons relative to that of neat PMMA coatings, according to measurements of electrochemical corrosion parameters. Additionally, incorporating silica particles into the polymer may effectively reduce the gas permeability of the polymer membrane. Reducing the size of silica particles (at the same silica feeding) further improved the gas barrier property. Optical clarity studies indicated that introducing silica particles into the PMMA matrix may slightly reduce the optical clarity of the films/membranes, as determined by UV‐visible transmission spectroscopy. The contact angle of H₂O of the hybrid films increased with the amount of aniline. Copyright © 2006 Society of Chemical Industry Society of Chemical Industry     

Dielectric and electrical characterization of (PEO–PMMA)–LiBF<Subscript>4</Subscript>–EC plasticized solid polymer electrolyte films

Plasticized solid polymer electrolytes (PSPEs) consisting of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend (50/50 wt%) based matrix with lithium tetrafluoroborate (LiBF₄) as dopant ionic salt (10 wt%) and varied concentrations (x = 0, 5, 10 and 15 wt%) of ethylene carbonate (EC) as plasticizer have been prepared. Classical solution-cast (SC) and the ultrasonic assisted followed by microwave irradiated (US–MW) solution-cast methods have been used for the preparation of (PEO–PMMA)–LiBF₄–x wt% EC films, and the same have been hot–pressed to get their smooth surfaces. Dielectric relaxation spectroscopy (DRS) and X–ray diffraction (XRD) techniques have been employed to characterize the dielectric and electrical dispersions and the structural properties of the PSPE films, respectively. It has been observed that the ionic conductivity of these semicrystalline ion-dipolar complexes is governed by their dielectric permittivity and polymers chain segmental dynamics. The increase in ionic conductivity values with the increase of plasticizer concentration in the PSPEs also varies with the films’ preparation methods. The US–MW method prepared PSPE film containing 15 wt% EC has a maximum ionic conductivity (1.86 × 10^?5 S cm^?1) at room temperature, whereas, the films having low concentrations of EC exhibit the conductivity of the order of 10^?6 S cm^?1.     

Organic‐acid‐catalyzed sol–gel route for preparing poly(methyl methacrylate)–silica hybrid materials

In this study, a series of organic–inorganic hybrid sol–gel materials consisting of a poly(methyl methacrylate) (PMMA) matrix and dispersed silica (SiO₂) particles were successfully prepared through an organic‐acid‐catalyzed sol–gel route with N‐methyl‐2‐pyrrolidone as the mixing solvent. The as‐synthesized PMMA–SiO₂ nanocomposites were subsequently characterized with Fourier transform infrared spectroscopy and transmission electron microscopy. The solid phase of organic camphor sulfonic acid was employed to catalyze the hydrolysis and condensation (i.e., sol–gel reactions) of tetraethyl orthosilicate in the PMMA matrix. The formation of the hybrid membranes was beneficial for the physical properties at low SiO₂ loadings, especially for enhanced mechanical strength and gas barrier properties, in comparison with the neat PMMA. The effects of material composition on the thermal stability, thermal conductivity, mechanical strength, molecular permeability, optical clarity, and surface morphology of the as‐prepared hybrid PMMA–SiO₂ nanocomposites in the form of membranes were investigated with thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, gas permeability analysis, ultraviolet–visible transmission spectroscopy, and atomic force microscopy, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Enhanced physical aging of polymer nanocomposites: The key role of the area to volume ratio

The physical aging process, namely the spontaneous evolution of the thermodynamic state occurring in glasses, has been monitored in poly(methyl methacrylate) (PMMA)/silica and polystyrene (PS)/silica nanocomposites following the time evolution of the enthalpy by means of differential scanning calorimetry (DSC). The effect on physical aging of the content of silica particles has been investigated in detail varying it over a wide range. Our results indicate accelerated physical aging in the nanocomposites in comparison to the corresponding pure polymer. Furthermore the acceleration is generally more pronounced in nanocomposites presenting a high silica content. This result cannot be attributed to a difference in molecular mobility of the polymers in the nanocomposites in comparison to pure PMMA and PS, since broadband dielectric spectroscopy (BDS) indicates no effect of silica nanoparticles on the polymer segmental dynamics. Moreover, calorimetric measurements reveal a reduction of the heat capacity jump at T_g for the nanocomposites, as well as lower experimentally recoverable enthalpy values. This may result from the faster non-isothermal evolution of the glass state when cooling down the samples from their liquid state. To account for these experimental results the acceleration of physical aging has been rationalized in the framework of the diffusion of free volume holes model as previously proposed. This is able to adequately catch the dependence of the physical aging rate on silica content, determining the area of nanoparticles to the volume of polymer, that is the relevant variable within the diffusion model.     

Effect of weakly interacting nanofiller on the morphology and viscoelastic response of polyolefins

Effect of silica nanofiller on the deformation response and morphology of low‐ and high‐density polyethylene (HDPE, LDPE) and isotactic polypropylene (PP) modified with fumed silica was investigated. The dynamic‐mechanical thermal spectroscopy, differential scanning calorimetry, optical microscopy, and density measurements were carried out to determine the temperature dependence of storage and loss moduli as well as nanocomposite morphology. It was demonstrated that the degree of matrix reinforcement is considerably affected by the extent of matrix crystallinity, especially, in the temperature range from (T_m–130°C) to T_m. Based on experimental evidence and literature review, it is proposed that this phenomenon may be attributed to the alpha‐mechanical relaxation process occurring above matrix T_g. As a result of adding silica into the melted matrix, mobility of chains in contact with silica particles became reduced. This caused substantial changes in morphology of these semicrystalline nanocomposites. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Relaxation behavior of layered double hydroxides filled dangling chain-based polyurethane/polymethyl methacrylate nanocomposites

A series of dangling chain based-polyurethane/poly(methyl methacrylate) (DPU/PMMA) filled with exfoliated layered double hydroxides (LDH) were synthesized by methyl methacrylate in-situ intercalative polymerization. The dangling chains were introduced by using vegetable oils as chain extender. The effect of dangling chain and the contents of LDH on the molecular dynamics of DPU/PMMA was investigated by a combination of dynamic mechanical analysis and broadband dielectric relaxation spectroscopy. Compared with polyurethane/poly(methyl methacrylate) (PU/PMMA) without dangling chain, the glass transition temperature (T_g) of DPU/PMMA shifts to lower temperature and the segmental dynamics becomes faster. A plateau with a high loss factor value above T_g significantly broadens the damping temperature range due to the synergy effect between the dangling chains and LDH layers. In DPU/PMMA/LDH nanocomposites, the α-relaxation associated with the glass transition of the polymer matrix becomes slower with the increase of LDH content, which indicates a restricted molecular mobility in the interfacial regions between polymer and LDH. However, the local relaxations at relatively low temperature remain unaffected by dangling chain or the addition of LDH. When the LDH content increases, Maxwell–Wagner–Sillars (MWS) interfacial polarization process caused by charge accumulation at interfaces becomes faster because of the smaller mean distance d between the exfoliated LDH layers.     

Glass transition and molecular dynamics in poly(dimethylsiloxane)/silica nanocomposites

The molecular dynamics of a series of poly(dimethylsiloxane) networks filled with silica nanoparticles synthesized in situ was investigated using thermally stimulated depolarization currents, broadband dielectric relaxation spectroscopy and differential scanning calorimetry. The techniques used cover together a broad frequency range (10⁻³-10⁹ Hz), thus allowing to gain a more complete understanding of the effects of the nanoparticles on the chain dynamics. In addition to the α relaxation associated with the glass transition of the polymer matrix, we observe in dielectric measurements a slower α relaxation which is assigned to polymer chains close to the polymer/filler interface whose mobility is restricted due to interactions with the filler surface. The thickness of the interfacial layer is estimated to be about 2.1-2.4 nm. Differential scanning calorimetry shows a change in the shape of the glass transition step, as well as a decrease in both the degree of crystallinity and the crystallization rate by the addition of silica.     

Effect of tacticity of poly(methyl methacrylate) on interfacial region with silica in polymer nanocomposite

The effect of tacticity on the interfacial region between poly(methyl methacrylate) (PMMA) and silica in a PMMA/silica nanocomposite was investigated by differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The glass transition temperature (T_g) values of the syndiotactic (st-) and atactic (at-) PMMA/silica nanocomposites are higher than those of the neat PMMA. Conversely, the T_g of the isotactic (it-) PMMA/silica nanocomposite is slightly higher than that of the neat it-PMMA. DSC and XRD results suggest that the restriction of the PMMA chain mobility in the silica nanoparticle interfacial region heightens as the syndiotactic content increases. FT-IR results show that this phenomenon is caused by the interaction between the carbonyl group of PMMA and the silanol group on the silicon dioxide surface. Therefore, it can be concluded that the syndiotactic-rich PMMA has a significantly different molecular mobility from that of the neat PMMA in the interfacial region with silica nanoparticle surface than isotactic-rich PMMA.     

Effect of side chain architecture on dielectric relaxation in polyhedral oligomeric silsesquioxane/polypropylene oxide nanocomposites

Segmental and normal mode dynamics in polyhedral oligomeric silsesquioxane (POSS)/poly(propylene oxide) (PPO) non-reactive and reactive nanocomposites were investigated using a broadband dielectric relaxation spectroscopy (DRS) over wide ranges of frequency and temperature. Three POSS reagents with varying side chain architecture were selected for the study: OctaGlycidyldimethylsilyl (OG), TrisGlycidylEthyl (TG) and MonoGlycidylEthyl (MG). Spectra of OG and TG show a segmental (α) process at lower frequency and a local (β) relaxation at higher frequency, while MG displays only a local relaxation. Neat PPO has both segmental and normal mode (α_N) process. In POSS/PPO non-reactive nanocomposites, the presence of OG and TG causes a decrease in the time scale of α_N and α relaxation, while MG has no impact on the dynamics of PPO. Chemical reactions in POSS/PPO reactive nanocomposites lead to the formation of nanonetworks. Prior to the onset of reaction, POSS nanoparticles promote the motions of PPO chains, decrease the time scale of relaxation and give rise to thermodielectrically simple spectra. During the reaction, however, the network formation leads to spectral broadening and a gradual increase in the time scale of both segmental (α) and normal mode (α_N) relaxation. A detailed account of the effects of structure, concentration and dispersion of POSS in the matrix, molecular weight of PPO, extent of reaction and temperature on the molecular origin, temperature dependence and spectral characteristics of relaxation processes in POSS/PPO nanocomposites is provided.     

Dielectric investigation on poly(methylmethacrylate) films doped with p-nitroaniline

The dielectric behaviour of solution-grown thin films of poly(methylmethacrylate) containing p-nitroaniline (p-NA) as a dopant was investigated within the temperature range 60–90°C and a 20–10⁵ Hz frequency band. It is shown that these mixtures exhibit only one relaxation process similar to that of pure PMMA. However, the addition of p-NA increases both the height and the relaxation strength of the peaks and also shifts log f_m to higher frequencies. The additive causes narrowing of the loss curves and increases the activation energy for relaxation. These results are interpreted in terms of the hydrogen bonding effects of p-NA on localized motions of carboxymethyl dipoles in PMMA. An insight into the possible origins of the β- and α-relaxations in PMMA is also presented.     

Dielectric properties of nylon 6/clay nanocomposites from on-line process monitoring and off-line measurements

Nylon 6/clay nanocomposites were studied by dielectric relaxation spectroscopy (DRS) to correlate morphology and microstructure with relaxation behavior of the polymer matrix at the molecular level. Partially exfoliated clay microstructure was achieved by extruding nylon 6 with surfactant-treated montmorillonite clays. A new on-line dielectric slit die sensor was used to examine the melt state properties during extrusion compounding. Solid state properties were probed by off-line DRS over a temperature range from −50 to 180 °C in a frequency range from 10⁻³ to 10⁶ Hz. Using non-linear regression methods in conjunction with the temperature-frequency positions of relaxations observed in the dielectric loss data, the experimental data were fit with the Havriliak-Negami and Cole-Cole dielectric relaxation functions corrected for electrode polarization and DC conductivity. Characteristic frequency, relaxation strength, and DC conductivities were extracted from curves with overlapping relaxation modes. Two dielectric relaxations were observed in the composite melt: the α relaxation associated with molecular segmental motion, and a Maxwell-Wagner relaxation (MW) resulting from interfacial polarization at the resin/clay interface. Analysis of the solid-state data yielded a comprehensive master plot of dielectric relaxations attributed to segmental and local molecular dynamics and other relaxations resulting from water and Maxwell-Wagner interfacial polarization. The impact of clay fillers is seen in nearly all relaxation processes changing both characteristic frequency and strength of the relaxation.     

Dynamics near the filler surface in natural rubber-silica nanocomposites

We study the effect of in situ synthesized 10 nm silica nanoparticles on the glass transition and dynamics of natural rubber networks using differential scanning calorimetry, broadband dielectric relaxation spectroscopy and thermally stimulated depolarization currents. Even in the absence of specific polymer-filler interactions, polymer segments within a few nanometers of the filler particles exhibit relaxation times up to 2-3 orders of magnitude slower and reduced heat capacity increment at the glass transition compared to bulk natural rubber. These effects are only observed when the nanoparticles are uniformly distributed in the polymer matrix.     

Biocompatibility and microscopic evaluation of polyurethane–poly(methyl methacrylate)–titnanium dioxide based composites for dental applications

We prepared and then blended polyurethanes (PUs) with poly(methyl methacrylate)s (PMMAs) and TiO₂ by varying the percentage compositions to form pellets. The chemistry of all of the blended samples was confirmed by Fourier transform infrared spectroscopy. The incorporation of TiO₂ into the PU–PMMA matrix was confirmed with scanning electron microscopy analysis. Differential scanning calorimetry analysis and compression testing was performed, and the results are discussed. The cytotoxicity level of the prepared blends displayed dependence on the composition ratio of the PU–PMMA blends. The results reveal that the optimum PU contents in the PU–PMMA–TiO₂ blend were responsible for its better biocompatibility. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39806.     

Dielectric relaxation in vinylidene fluoride–hexafluoropropylene copolymers

The molecular mobility in copolymers of vinylidene fluoride–hexafluoropropylene VDF/HFP of 93/7 and 86/14 ratios has been investigated by means of broadband dielectric relaxation spectroscopy (10^?1–10⁷ Hz), differential scanning calorimetry DSC (?100 to 150°C), and of wide angle X‐ray diffraction WAXS. Four relaxation processes and one ferroelectric‐paraelectric phase transition have been detected. The process of the local mobility β‐ (at temperatures below glass transition point) is not affected by chemical composition of the copolymer and the formed structure. Parameters of segmental mobility in the region of glass transition (α_a‐relaxation) depend on the ratio of comonomer with lower kinetic flexibility. α_c‐relaxation is clearly observed only in VDF/HFP 93/7 copolymer, which is characterized by a higher crystallinity and a higher perfection of crystals of α‐ (α_p‐) phase. Diffuse order–disorder relaxor type ferroelectric transition connected with the destruction of the domains in low‐perfect ferroelectric phase in the amorphous regions has been detected for both copolymers. An intensive relaxation process (α‐process) was observed for both copolymers in high‐temperature region. DSC data shows that it falls on the broad temperature region of α‐phase crystals melting. It is considered to be connected with the space charge relaxation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Dielectric properties of copolymers based on cyano monomers and methyl α‐acetoxyacrylate

With the aim of developing dielectric polymers containing CN groups with strong dipole moment, alternating and statistical copolymers of the cyano monomers vinylidene cyanide (VCN), acrylonitrile and methacrylonitrile with methyl α‐acetoxyacrylate (MAA) were synthesized and characterized. The copolymer's composition and microstructure were analysed by NMR spectroscopy, SEC and elemental analysis. The reactivity ratios calculated from the Q–e Alfrey–Price parameters for these copolymers indicated the alternating and statistical structures confirmed by NMR analysis. The copolymers have glass transition temperatures T_g in the range 83–146 °C and are stable up to 230 °C. The thermal stability of the copolymers depends on the nature of the cyano monomers. Their molecular dynamics were investigated by dielectric relaxation spectroscopy. We revealed a weak relaxation β at sub‐T_g temperature for poly(VCN‐co‐MAA) usually originating from molecular motions that are restricted to the scale of a few bond lengths. Strong α‐relaxation processes occurred above T_g for these copolymers. This primary relaxation was associated with cooperative movements of the polar groups (CN) at the time of mobility of the principal chains. The activation energy of the α‐relaxation process was also calculated. The values of the dielectric increment Δε for these copolymers were determined by Cole–Cole plots and indicated that the copolymers exhibit interesting dielectric properties compared with similar cyano materials. The polarity–permittivity relationship was also established. © 2012 Society of Chemical Industry