PVDF Chains Research Articles

Crystalline structure, dielectric, and mechanical properties of simultaneously biaxially stretched polyvinylidene fluoride film

Biaxially stretched films have balanced properties in the film plane compared with uniaxially stretched films, thus having wider potential applications. In this paper, the simultaneously biaxial stretching (BO) technology had been applied to poly (vinylidene fluoride) (PVDF) melt extrusion film, and the crystalline structure, dielectric, and mechanical properties of the BOPVDF films were investigated. The results showed that during the simultaneous BO process, the applied stress on the film led to the alignment of PVDF chains into the crystals and the formation of all‐trans planar zigzag (TTT) conformation, thus increasing the relative content of β phase and the crystallinity of BOPVDF films, as well as the dielectric response. When the stretching ratio was 2.0 × 2.0, the dielectric constant of the film reached the maximum, ie, ~12, and the dielectric loss was minimum, ie, ~0.02. At the same time, the mechanical properties of the stretched films were significantly improved and reached the maximum tensile strength with 3.5 × 3.5 draw ratio, ie, 90 MPa.

Phase-Separation-Induced PVDF/Graphene Coating on Fabrics toward Flexible Piezoelectric Sensors.

Clothing-integrated piezoelectric sensors possess great potential for future wearable electronics. In this paper, we reported a phase-separation approach to fabricate flexible piezoelectric sensors based on poly(vinylidene fluoride) (PVDF)/graphene composite coating on commercially available fabrics (PVDF/graphene@F). The structural units of -CH2- and -CF2- of PVDF chains were arranged directionally due to the structural induction of graphene and water during phase separation, which is the key for electroactive phase enrichment. In optimized case, integrating into fabric substrates endows the phase-out PVDF/graphene composite coating 4 times higher voltage output than its film counterpart. Piezoelectric sensor based on PVDF/graphene@F exhibits a sensitivity of 34 V N-1, which is higher than many reports. It also shows low detecting threshold (0.6 mN), which can be applied to distinguish the voices or monitor the motion of body. This simple and effective approach toward PVDF/graphene@F with excellent flexibility provides a promising route toward the development of wearable piezoelectric sensors.

Atomistic Modeling of the Formation of a Thermoset/Thermoplastic Interphase during Co-Curing

Co-curing of a thermoset epoxy matrix in contact with thermoplastic foils is an essential step in damage-free joining of polymers or polymer-based composites. We present results of all-atom molecular dynamics simulations that shed light onto the resulting hybrid interface. Using poly(vinylidene difluoride) (PVDF) and a multicomponent epoxy resin as model systems, we have developed a computational co-curing protocol that ensures both adequate structural representation and mobility of the PVDF chains and a realistic cross-linking conversion and topology of the epoxy resin. As a result, we reveal that mutually entangled loops of thermoplastic chains and resin strands form across the interface within the extended interphase region separating the two polymers. In tensile stress simulations we find that these loops contribute to a surprisingly large interfacial strength. In the absence of extrinsic defects, failures nucleate at the PVDF side of the interphase and propagate via a chain-pullout mechanism characteristic of semi-interpenetrating polymer networks involving thermoplastic materials.

Improvement of β-phase crystal formation in a BaTiO3-modified PVDF membrane

In this paper, low temperature plasma is used to modify the surface of barium titanate (BaTiO3) nanoparticles in order to enhance the interfacial compatibility between ferroelectric poly(vinylidene fluoride) (PVDF) and BaTiO3 nanoparticles. The results demonstrate that oxygenic groups are successfully attached to the BaTiO3 surface, and the quantity of the functional groups increases with the treatment voltage. Furthermore, the effect of modified BaTiO3 nanoparticles on the morphology and crystal structure of the PVDF/BaTiO3 membrane is investigated. The results reveal that the dispersion of BaTiO3 nanoparticles in the PVDF matrix was greatly improved due to the modification of the BaTiO3 nanoparticles by air plasma. It is worth noting that the formation of a β-phase in a PVDF/modified BaTiO3 membrane is observably promoted, which results from the strong interaction between PVDF chains and oxygenic groups fixed on the BaTiO3 surface and the better dispersion of BaTiO3 nanoparticles in the PVDF matrix. Besides, the PVDF/modified BaTiO3 membrane at the treatment voltage of 24 kV exhibits a lower water contact angle (≈68.4°) compared with the unmodified one (≈86.7°). Meanwhile, the dielectric constant of PVDF/BaTiO3 nanocomposites increases with the increase of working voltage.

Preparation and characterization of functional poly(vinylidene fluoride) (PVDF) membranes with ultraviolet-absorbing property

We first reported a strategy to prepare functional poly(vinylidene fluoride) (PVDF) membranes with excellent ultraviolet-absorbing property through chemically induced grafting. Herein, the polymerizable ultraviolet (UV) absorber 2-hydroxy-4-(3-methacryloxy-2-hydroxylpropoxy) benzophenone (BPMA) made by ourselves was grafted onto the PVDF chains that have been pretreated with tetraethylammonium hydroxide (TEAH) alkaline solution. Moreover, the effect of experiment conditions such as the alkali and monomer concentrations, alkali treatment time on the UV-absorbing property of the obtained PVDF-g-PBPMA membranes were studied in detail. The chemical structure of the modified membranes was confirmed by 1H NMR, FT-IR and XPS measurements. Meanwhile, the thermal and UV-absorbing properties were characterized by TGA, DSC and UV-Vis spectrophotometer, respectively. The results indicated that BPMA side chains were successfully introduced onto PVDF backbones. Most importantly, the obtained PVDF-g-PBPMA membranes exhibited excellent UV-absorbing property. The transmittance of UV light at 300 nm decreased to as low as 0.02% and the UV light below 388 nm could be completely absorbed by the PVDF-g-PBPMA membrane made under optimal condition.

Effect of annealing treatment on crystalline and dielectric properties of PVDF/PEG-containing ionic liquid composites

To investigate the effect of poly(ethylene glycol)-containing ionic liquid (IL) and thermal annealing treatment on crystallization and dielectric relaxation behavior of poly(vinylidene fluoride) (PVDF), a series of PVDF/IL composites have been prepared using a solution-cast method. The interaction between imidazolium cation of ILs and >CF2 groups of PVDF can transfer nonpolar α phase to polar β and γ phase as a template at the primary crystallization, and then the interaction between PEG of ILs and >CF2 groups of PVDF can facilitate the PVDF chains in amorphous region to bring more polar phase and decrease the degree of crystallization for PVDF composites according to the template under thermal annealing treatment. The experimental dielectric data were analyzed within the formalisms of complex permittivity and electric modulus. In the frequency spectra of PVDF composites, dc conductivity, electrode and Maxwell-Wagner-Sillars (MWS) interfacial polarization resulted in high values of dielectric permittivity. The incorporation of ILs into the matrix and thermal annealing treatment can accelerate dc conductivity. The temperature dependence of relaxation time of dc conductivity follows the Arrhenius equation. The effect of annealing treatment on charge carrier movement mechanism was resulted from the increase of ion mobility induced by polymer chain segmental motion and polar phase crystals.

Crosslinked electrospun poly(vinylidene difluoride) fiber mat as a matrix of gel polymer electrolyte for fast-charging lithium-ion battery

Gel polymer electrolyte (GPE), possessing a polymer matrix and embedded liquid electrolyte, is a critical component of lithium-ion batteries. To enhance GPE performance, in this work a self-crosslinkable poly(vinylidene difluoride) (PVdF) graft copolymer possessing Meldrum's acid (MA) groups as reactive sites has been prepared with atom transfer radical polymerization and utilized as a polymer matrix for GPEs. Compared to neat PVdF based GPEs, incorporation of MA groups to PVdF chains simultaneously brings crosslinking characteristic and high polarity to PVdF chains so as to enhance the thermal stability, mechanical strength, and polymer matrix-electrolyte affinity of the corresponding GPEs. The prepared GPE has an ionic conductivity of about 1.48 mS cm−1, which is higher than the value of 0.98 mS cm−1 measured on commercial Celgard 2325® separator. Moreover, good Li-ion battery performance, including high discharge capacity (136 mAh g−1 at 0.2 C) and high capacity retention at high C-rates (66% at 10 C and 50% at 15 C), has been recorded with the prepared GPE based LIBs, demonstrating the application potential of the developed GPE for fast-charging lithium-ion batteries.

Synthesis of hydrophilic carbon nanotubes by grafting poly(methyl methacrylate) via click reaction and its effect on poly(vinylidene fluoride)-carbon nanotube composite membrane properties

Surface modification of azide-decorated multiwalled carbon nanotubes (MWCNTs) with well-defined alkyne-terminated poly(methyl methacrylate) (PMMA) chains was accomplished via the combination of reversible addition fragmentation chain transfer (RAFT) and “click” chemistry. Successful attachment of PMMA onto MWCNT was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), gel permeation chromatography, Raman spectroscopy, and transmission electron microscopy. The highest grafting percentage (GP) of the PMMA chains (GP=23.3%) was calculated using TGA. The effect of the PMMA-grafted-MWCNTs (MWCNTs-g-PMMA) content on the performance of the poly(vinylidene fluoride) (PVDF)-MWCNTs-g-PMMA composite membrane was studied. The MWCNTs-g-PMMA was found to be well dispersed in the PVDF composite membrane matrix because of the excellent compatibility between the PMMA and PVDF chains. The composite membranes showed improved porosity, hydrophilicity, water flux, β-PVDF content, and mechanical properties at an optimal amount of 2wt% MWCNTs-g-PMMA incorporated in the PVDF membrane matrix. In contrast, the hydroxyl functionalized MWCNTs (MWCNTs-OH) showed limited enhancement in the water flux and mechanical strength, which is mainly due to the poor dispersion of MWCNT because of the weak interaction between the MWCNT and PVDF chains. This study reveals the excellent prospect of the MWCNT-based ultrafiltration membrane with enhanced properties in water treatment applications.

Performance improvement of poly(vinylidene fluoride) by in situ copolymerization of methyl methacrylate and ionic liquid

1-Butyl-3-vinylimdazolium tetrafluoroborate ([BVIM][BF4]) was used as ionic liquid to in situ copolymerized with methyl methacrylate (MMA) in poly(vinylidene fluoride) (PVDF) solution by the free radical polymerization method. The content of [BVIM][BF4] in the copolymerized monomers ranges from 0 to 50%. Soxhlet extraction results showed that more than 60% P(MMA-co-[BVIM][BF4]) were grafted onto the PVDF chains and the grafting degree was higher than 15%. 1H NMR tests proved the occurrence of grafting reaction. SEM morphology indicated that phase separation took place for the in situ PVDF/P(MMA-co-[BVIM][BF4]) composites when the [BVIM][BF4] content was more than 40 wt%. FTIR and XRD measurements indicated the crystal transformation of PVDF from α-phase to s/γ phase due to the ion-dipole interaction between PVDF and [BVIM][BF4]. Furthermore, the introduction of [BVIM][BF4] into the in situ PVDF/P(MMA-co-[BVIM][BF4]) composites enhanced the electrical conductivity and dielectric constant of PVDF. The present method improved the stability of ionic liquid in the PVDF composites and the in situ PVDF/P(MMA-co-[BVIM][BF4]) composites show potential applications in sensor, actuator and battery fields.

Synergistic Coupling between Li6.75La3Zr1.75Ta0.25O12 and Poly(vinylidene fluoride) Induces High Ionic Conductivity, Mechanical Strength, and Thermal Stability of Solid Composite Electrolytes.

Easy processing and flexibility of polymer electrolytes make them very promising in developing all-solid-state lithium batteries. However, their low room-temperature conductivity and poor mechanical and thermal properties still hinder their applications. Here, we use Li6.75La3Zr1.75Ta0.25O12 (LLZTO) ceramics to trigger structural modification of poly(vinylidene fluoride) (PVDF) polymer electrolyte. By combining experiments and first-principle calculations, we find that La atom of LLZTO could complex with the N atom and C═O group of solvent molecules such as N,N-dimethylformamide along with electrons enriching at the N atom, which behaves like a Lewis base and induces the chemical dehydrofluorination of the PVDF skeleton. Partially modified PVDF chains activate the interactions between the PVDF matrix, lithium salt, and LLZTO fillers, hence leading to significantly improved performance of the flexible electrolyte membrane (e.g., a high ionic conductivity of about 5 × 10-4 S cm-1 at 25 °C, high mechanical strength, and good thermal stability). For further illustration, a solid-state lithium battery of LiCoO2|PVDF-based membrane|Li is fabricated and delivers satisfactory rate capability and cycling stability at room temperature. Our study indicates that the LLZTO modifying PVDF membrane is a promising electrolyte used for all-solid-state lithium batteries.

Nucleation barrier, growth kinetics in ternary polymer blend filled with preferentially distributed carbon nanotubes

Structural properties, evolution of morphology and crystallization kinetics in immiscible polymer blends filled with multiwall carbon nanotubes (MWNTs) in the droplet phase were systematically investigated in this study. By grafting suitable macromolecules (here SAN, styrene acrylonitrile), that can drive the MWNTs to the droplet phase, allowed the understanding of the rate of nucleation and growth of the semicrystalline matrix in droplet-filled blends in contrast to matrix-filled blends. By blending 90 wt% of PVDF with 10 wt% ABS, matrix-droplet morphologies were generated and by grafting SAN onto MWNTs, the localization of the nanotubes was tuned to fill the droplet phase which otherwise prefers the matrix phase (here PVDF); driven by thermodynamics. The evolution of morphology under quiescent annealing conditions was assessed by SEM. The blends with SAN-g-MWNTs also coarsened as a function of time similar to neat blends however, to a lesser extent. Although, droplet laden MWNTs did not suppress coarsening in the blends but it still improved the tensile properties when compared with the neat blends. The fold surface free energy (as evaluated from isothermal crystallization kinetics) was estimated to be less in case of blends with only MWNTs in contrast to blends with SAN-g-MWNTs. This was attributed to the fact that matrix (here PVDF) filled with MWNTs experiences faster crystallization rate due to heterogeneous dispersion of nucleating agents (here MWNTs) in the matrix. However, when the SAN-g-MWNTs were mostly localized in the amorphous droplet phase (here ABS), PVDF experienced similar crystallization behavior like the neat PVDF/ABS blends. Taken together, our study demonstrates that lower amount of energy is required for the arrangement of PVDF chains into the crystal lattice upon cooling from the melt state and accelerate the crystallization process when the heteronucleating agents are localized in the matrix phase than when they are localized in the amorphous droplet phase.

Electroactive and High Dielectric Folic Acid/PVDF Composite Film Rooted Simplistic Organic Photovoltaic Self-Charging Energy Storage Cell with Superior Energy Density and Storage Capability.

Herein we report a simplistic prototype approach to develop an organic photovoltaic self-charging energy storage cell (OPSESC) rooted with biopolymer folic acid (FA) modified high dielectric and electroactive β crystal enriched poly(vinylidene fluoride) (PVDF) composite (PFA) thin film. Comprehensive and exhaustive characterizations of the synthesized PFA composite films validate the proper formation of β-polymorphs in PVDF. Significant improvements of both β-phase crystallization (F(β) ≈ 71.4%) and dielectric constant (ε ≈ 218 at 20 Hz for PFA of 7.5 mass %) are the twosome realizations of our current study. Enhancement of β-phase nucleation in the composites can be thought as a contribution of the strong interaction of the FA particles with the PVDF chains. Maxwell-Wagner-Sillars (MWS) interfacial polarization approves the establishment of thermally stable high dielectric values measured over a wide temperature spectrum. The optimized high dielectric and electroactive films are further employed as an active energy storage material in designing our device named as OPSESC. Self-charging under visible light irradiation without an external biasing electrical field and simultaneous remarkable self-storage of photogenerated electrical energy are the two foremost aptitudes and the spotlight of our present investigation. Our as fabricated device delivers an impressively high energy density of 7.84 mWh/g and an excellent specific capacitance of 61 F/g which is superior relative to the other photon induced two electrode organic self-charging energy storage devices reported so far. Our device also proves the realistic utility with good recycling capability by facilitating commercially available light emitting diode.

Enhanced dc conductivity and conductivity relaxation in PVDF/ionic liquid composites

To investigate the effects of 1-benzyl-3-methylimidazolium hexafluorophosphate on the crystal phase, morphology and dielectric relaxation behavior of poly(vinylidene fluoride) (PVDF), a series of PVDF/IL composites have been prepared using solution-cast method. The interaction between ILs and >CF2 groups of PVDF can facilitate the PVDF chains in amorphous area to form more polar phase for PVDF composites. In the frequency spectra of PVDF composites, MWS interfacial polarization, electrode polarization and dc conductivity resulted in high values of dielectric permittivity. The incorporation of ILs into the matrix can accelerate dc conductivity. The effect of IL on charge carrier movement mechanism was resulted from the increase of ion mobility induced by polar phase crystal and ion concentration.

Effect of solvent on the dipole rotation of poly(vinylidene fluoride) during porous membrane formation by precipitation in alcohol baths

Microporous PVDF membranes were prepared by isothermal immersion precipitation of PVDF/DMSO and PVDF/TEP casting dopes in different alcohol baths. The formed membranes exhibited the so-called particulate morphology, being packed by interconnected crystalline particles of a similar size. For the alcohol/TEP/PVDF system, the particles appeared as sheaf-like spherulites consisting of curled lamellae with thickness of ∼15 nm. In contrast, for the alcohol/DMSO/PVDF system, the formed membranes comprise relatively compact globules whose surface was covered with granular objects of ca. 30 nm dia. Wide angle X-ray diffraction patterns of the membranes indicate that the sheaf-like crystals were of the α-type structure, while the compact globules the γ-type structure, as were confirmed by FTIR-ATR analyses. 19F NMR spectroscopy indicated that PVDF chains exhibited TG+TG− conformation in TEP and T3G+T3G− conformation in DMSO. These conformations remained unchanged during immersion-precipitation to yield the α- and γ-type crystal structures. The crystallinity of the membranes, as determined by X-ray diffraction and differential scanning calorimetry, was found to be ∼68%. Furthermore, desalination by membrane-distillation of 3.5% NaCl(aq) feed at 50 °C were carried to see the desalination capability of the membranes. High fluxes (10–13 LMH) and rejections (∼99.8%) were obtained for both types of membranes.

Effect of anion type in the performance of ionic liquid/poly(vinylidene fluoride) electromechanical actuators

Low voltage actuators based on poly(vinylidene fluoride) (PVDF) with 10, 25 and 40% 1-hexyl-3-methylimidazolium chloride ([C6mim][Cl]) and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C6mim][NTf2]) are prepared by solvent casting in order to evaluate the effect of anion size in the bending properties. Independently of the ionic liquid type and content, its presence leads to the crystallization of PVDF in the β-phase. The addition of ionic liquid into the polymer matrix decreases significantly its degree of crystallinity and the elastic modulus. It is also confirmed the good miscibility between PVDF and IL, determined by the interaction of the CF2 groups from the PVDF chains with the imidazolium ring in the ionic liquid (IL). The AC conductivity of the composites depends both on the amount of ionic liquid content and anion size.The bending movement of the IL/PVDF composites is correlated to their degree of crystallinity, mechanical properties and ionic conductivity value and the best value of bending response (0.53%) being found for IL/PVDF composite with 40wt% of [C6mim][Cl] at an applied voltage of 10V square signal.

Hierarchical nanostructured polyaniline functionalized graphene/poly(vinylidene fluoride) composites for improved dielectric performances

Abstract Hierarchical nanostructured polymeric dielectric composites (PGP) based on semicrystalline poly (vinylidene fluoride) (PVDF) matrix are fabricated by incorporating polyaniline-grafted-graphene oxide (G-graft-PANI). HR-TEM images show uniform dispersion of GO within PVDF matrix. FE-SEM micrographs of PGP composites indicate fibrillar morphology produced from supramolecular organization of G-graft-PANI with PVDF chains resulting hierarchical nanostructure. The dipolar interaction between the filler and PVDF is established from FTIR spectra and Raman spectroscopy indicates reduction of GO during fabrication process. The interaction ability and high surface area of G-graft-PANI cause nonpolar α-phase PVDF to polar β-phase transformation to 91% for 5 wt% filler. PGP composites show higher melting and crystallization temperatures. It exhibit spectacular increase of dielectric permittivity, dielectric loss, and dc-conductivity relative to that of neat PVDF films. The values of dielectric permittivity and dielectric loss are 264 and 1.125 at 102 Hz frequency and dc-conductivity increases 8 orders from that of pristine PVDF for loading of 5% G-graft-PANI.

Limits of Vinylidene Fluoride RAFT Polymerization

The investigations reported in this article probe the behavior of the RAFT polymerization of vinylidene fluoride (VDF) when degrees of polymerization higher than 50 are targeted: they demonstrate that higher molar mass PVDF (11 000 g mol–1) can indeed be prepared by RAFT polymerization, but only at rather low monomer conversions (<33%). This study more carefully examines the behavior of the reputedly nonreactive −CF2CH−XA chain ends (where XA designates the xanthate group) formed by inverse VDF addition and known to accumulate in the reaction medium during the polymerization. A combination of 1H and 19F NMR spectroscopic monitoring and comprehensive DFT calculations of the various exchange and propagation reactions at work explains the unexpected behavior of this polymerization. The present study disproves entirely the generally accepted belief that −CF2CH2–XA-terminated PVDF chains are “dead” and shows how these chains are reactivated, albeit slowly, throughout the polymerization. This activation occurs prevalently and counterintuitively through degenerative exchange by the minority PVDF–CF2CH2• radicals. The resulting kinetic scheme rationalizes the experimentally observed absence, after conversion of all the dormant chains into the less reactive −CF2CH2–XA end-group, of the longer polymer chains expected from a free radical polymerization mechanism.

Largely restricted nucleation effect of carbon nanotubes in a miscible poly(vinylidene fluoride)/poly(butylene succinate) blend

AbstractThe crystallization behaviors of miscible poly(vinylidene fluoride)/poly(butylene succinate) (PVDF/PBS) and its blend composites with carbon nanotubes (CNTs) during non‐isothermal and isothermal processes were investigated. The results showed that CNTs acted as heterogeneous nucleation agents and further improved the nucleation ability of PBS and PVDF in blends. However, compared with the nucleation effects of CNTs in PBS/CNT or PVDF/CNT binary composites, the nucleation effect of CNTs in miscible PVDF/PBS was largely restricted and nucleation efficiency was lowered. A reasonable explanation about the restricted nucleation ability of CNTs was studied from the viewpoint of interfacial interactions between polymer components and CNTs, in which a preferential affinity of CNTs to PBS was found. Further combined with the preparation method, it is proposed that PVDF chains adsorbed on the CNT surface in the master batch were peeled off from the CNTs by incorporated PBS chains, due to the better interaction between PBS and CNTs. Finally, the PVDF chains at the interface were diluted by PBS, and most of the CNT surface was covered by PBS chains, giving rise to the nucleation of PBS on the CNTs. On the other hand, unremoved PVDF still adsorbed on the CNT surface and crystallized. Compared with PVDF/CNT and PBS/CNT binary composites, the nucleation density in the ternary composites was greatly lowered, resulting in restricted nucleation effects of CNTs. On the other hand, the preferable adsorption of PBS on CNTs induced an apparent phase fluctuation in the PVDF/PBS blend composites, which also reflected the selective adsorption of PBS on the CNT surface. © 2016 Society of Chemical Industry

Thermomechanical properties and long-term behavior evaluation of poly(vinylidene fluoride) (PVDF) exposed to bioethanol fuel under heating

DMTA was employed to evaluate the aging of poly(vinylidene fluoride) (PVDF) exposed to ethanol fuel derived from sugarcane. For this purpose, DMTA tests of aged and unaged PVDF were carried out, and the behaviors of E′, E″ and tan δ curves were carefully investigated. Using the time–temperature superposition principle, the PVDF long-term behavior was evaluated through E′ master curves multiple frequencies (T ref = 25 and 30 °C). PVDF suffered significant changes in DMTA properties, mainly in $$ T_{\text{g}}^{\prime } $$ region. Thus, the $$ T_{\text{g}}^{\prime } $$ values were shifted toward T g, ending up as one continuous relaxation. By hydrogen bonds, ethanol attenuated the secondary interactions of the PVDF chains in the constrained and free amorphous phases, reducing E′ by plasticization. However, the ethanol molecules also decreased the PVDF long-chain mobility by steric effect, reducing E″ and increasing the T g activation energy. Since aging in ethanol was accelerated by temperature, annealing in the air was also carried out to separate the thermally induced effects. Although the aging/annealing experiments indicated good compatibility between PVDF and ethanol, both treatments changed the PVDF thermomechanical properties and E′ master curves behavior. However, the nature of these changes was different in each case, and the material loses mechanical performance and long-term durability only when exposed to the combination of both.

Local Grafting of Ionic Liquid in Poly(vinylidene fluoride) Amorphous Region and the Subsequent Microphase Separation Behavior in Melt.

Polymer-based nanostructures can be generally created by self-assembly of block copolymers that are commonly synthesized by living radical polymerization. In this study, a new strategy is proposed to fabricate block-like copolymers by using the template of binary phase structure of semicrystalline polymers. Poly(vinylidene fluoride) (PVDF) is thermodynamically miscible with an unsaturated ionic liquid (IL) (1-vinyl-3-ethylimidazolium tetrafluoroborate) in the melt and IL molecules are expelled out from the crystalline parts during the crystallization of PVDF. Therefore, the IL molecules are only located at the amorphous region of PVDF crystals. The electron beam irradiation of the IL incorporated PVDF leads to the local grafting of IL molecules onto the PVDF molecular chains in the amorphous region, so block-like grafting polymer chains of crystalline PVDF-b-(amorphous PVDF-g-IL)-b-crystalline PVDF can be achieved. The subsequent heating of the irradiated sample induces the microphase separation of PVDF-g-IL from the ungrafted PVDF chains.