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Chemical structure of the thermoplastic polyetherimide (PEI) repeat units: 3,3′,4,4′-oxydiphthalic dianhydride (ODPA)-P3 and 2,3′,3,4′-biphenyltetracarboxylic dianhydride (aBPDA)-P3. Arrows mark the vectors D and P aligned along phenylene and phthalimide planar moieties of the polyetherimide chains under study, for which the orientation to the nanotube axis was investigated in this paper. Phenylene rings in the moiety designated by the D vector can rotate out of a planar structure; however, such deviations from a planar structure are small, especially in the vicinity of the CNT surface, and phenylene rings are mostly coplanar.
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Crystallization of all-aromatic heterocyclic polymers typically results in an improvement of their thermo-mechanical properties. Nucleation agents may be used to promote crystallization, and it is well known that the incorporation of nanoparticles, and in particular carbon-based nanofillers, may induce or accelerate crystallization through nucleati...
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... backbone of both polymers is almost identical with the exception of the dianhydrides used. 3,3′,4,4′- oxydiphthalic dianhydride (ODPA) induces a slight kink in the polymer backbone, whereas 2,3′,3,4′- biphenyltetracarboxylic dianhydride (aBPDA) induces a local 90° kink in the polymer backbone, which severely compromises the backbone linearity; see Figure 1. 3,3′,4,4′-oxydiphthalic dianhydride (ODPA)-P3 and 2,3′,3,4′-biphenyltetracarboxylic dianhydride (aBPDA)-P3. ...
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... order to study the intermolecular structure at the polymer-SWCNT interface, we analyzed the orientation-related ordering of the PEI chain planar moieties shown by the vectors P or D in Figure 1. It should be noted that the phenylene rings designated by the vector D could form non-planar conformations due to the rotation of the rings. ...
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... PEIs are reinforced with single-walled carbon nanotubes (SWCNTs). The molecular structures are shown in Figure 1. ...
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... simulation timescale is close to the slowest relaxation processes related to moving a polymer coil over distances comparable to its own size, as was shown for the R-BAPB and R-BAPS aromatic polyetherimides with polymerization degree Np = 8 at temperature 600 K [55,62]. During equilibration, the average sizes of polymer chains reached their equilibrium values, which are in good agreement with the theoretical estimates; see Figure S1 in the Supplementary Materials. To investigate the polymer structure at the polymer-CNT interface, the 1 μs-long production runs were performed at T = 600 К and T = 580 К. ...
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... the dependence r of ODPA-P3 has a more pronounced second maximum, which shows that the ODPA-P3 chains adsorb more strongly onto the CNT surface than the aBPDA-P3 chains. In order to study the intermolecular structure at the polymer-SWCNT interface, we analyzed the orientation-related ordering of the phenylene and phthalimide planar moieties in the PEI chains, represented by the D and P vectors in Figure 1 correspondingly, and calculated the order parameters, () Sr ...
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... change of the form of excluded volume interaction potential was followed by additional simulation for 1 µ s. Then, we calculated the dependences of the order parameter () Sr and density r of the ODPA-P3 on the distance from the CNT axis and distributions of the orientation angles between the ODPA-P3 planar moieties and CNT axis; see Figure 10. ...
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... analysis of the data presented in Figure 10 allows us to conclude that 1-µ s simulation using the WCA potential instead of the LJ potential leads to the destruction of the structural ordering of the ODPA-P3 planar segments near the CNT surface. The dependence of the order parameter ( Notably, when the simulation was extended to 2 µ s, there was still no structural ordering of the ODPA-P3 planar moieties near the CNT surface; see Figure S5 in the Supplementary Materials. ...
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... the value of the parameter ε, we sought to efficiently relax or enhance the π-π interactions at the polymer-CNT phase interface. Figure 11 shows dependences ...
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... we investigated the structural properties of ODPA-P3. To this end, we calculated () Sr , r and distributions of the orientation angles between the PEI planar fragments and the CNT axis; see Figure 12. ...
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... Figure 12a. This may be attributed to the fact that after a 10-times reduction of the potential well depth , the ODPA-P3 atoms cannot adsorb on the CNT surface due to thermal fluctuations. ...
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... the parameter is increased by five-times, the dependence () Sr demonstrates the rise of the first maximum height, which confirms the fact that the ODPA-P3 heterocyclic rings find it more energetically favorable to orient themselves near the CNT surface. The analysis of the dependence r for varying ε values shows that the increase in ε also causes the height of the first and second maxima to grow in the dependence r of ODPA-P3, as well; see Figure 12b. With ε increasing, this polyetherimide starts to be more strongly attracted to the CNT surface. ...
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... conclusions are substantiated also by the analysis of the distribution of orientation angles of the PEI planar fragments relative to the CNT axis. The results obtained have demonstrated that the reduction of the parameter ε by 10-times in the distribution of the orientation angles (Figure 12с) causes the second and third ordered polymer layers near the CNT surface to disappear, whereas these layers were observed earlier using the standard parameters of the force field; see Figure 6a. In the case of the five- times increase in the parameter , distributions of the orientation angles feature the first peak at a distance of ≈0.75-0.8 ...
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... the case of the five- times increase in the parameter , distributions of the orientation angles feature the first peak at a distance of ≈0.75-0.8 nm, where the planar fragments of the ODPA-P3 repeat unit are oriented at an angle of ~10°, and the second peak at a distance of ≈1.25-1.5 nm, where the planar moieties are oriented at an angle of ≈20°; see Figure 12d. The analysis of the results obtained shows a strong influence of specific π-π interactions of the polymer-CNT interface structure. ...
Citations
... The structural ordering of semicrystalline PIs in simulations is observed even at temperatures slightly higher than the experimental melting temperatures [70,89]. This modeling is physically valid because the simulation results may provide a higher melting temperature of the polymer compared to the experimental findings [90]. ...
Over the past few decades, the enhancement of polymer thermal conductivity has attracted considerable attention in the scientific community due to its potential for the development of new thermal interface materials (TIM) for both electronic and electrical devices. The mechanical elongation of polymers may be considered as an appropriate tool for the improvement of heat transport through polymers without the necessary addition of nanofillers. Polyimides (PIs) in particular have some of the best thermal, dielectric, and mechanical properties, as well as radiation and chemical resistance. They can therefore be used as polymer binders in TIM without compromising their dielectric properties. In the present study, the effects of uniaxial deformation on the thermal conductivity of thermoplastic PIs were examined for the first time using atomistic computer simulations. We believe that this approach will be important for the development of thermal interface materials based on thermoplastic PIs with improved thermal conductivity properties. Current research has focused on the analysis of three thermoplastic PIs: two semicrystalline, namely BPDA-P3 and R-BAPB; and one amorphous, ULTEMTM. To evaluate the impact of uniaxial deformation on the thermal conductivity, samples of these PIs were deformed up to 200% at a temperature of 600 K, slightly above the melting temperatures of BPDA-P3 and R-BAPB. The thermal conductivity coefficients of these PIs increased in the glassy state and above the glass transition point. Notably, some improvement in the thermal conductivity of the amorphous polyimide ULTEMTM was achieved. Our study demonstrates that the thermal conductivity coefficient is anisotropic in different directions with respect to the deformation axis and shows a significant increase in both semicrystalline and amorphous PIs in the direction parallel to the deformation. Both types of structural ordering (self-ordering of semicrystalline PI and mechanical elongation) led to the same significant increase in thermal conductivity coefficient.
... It was proven that even a slight variation in the chemical structure could have a profound effect on the crystallinity of a polymer [28,30,37,38]. In our previous studies, we investigated the mechanical and thermophysical properties of PEIs developed by the group of Prof. Dingemans and the nanocomposites based upon them, and obtained qualitative agreement between the simulation and the experimental data [28,29,39,40]. ...
... The set of parameters for potential functions corresponded to the Gromos53a6 force field, which has been used successfully to simulate the thermal and mechanical properties of thermoplastic PEIs [58,59], and in particular BPDA-P3 [28,40]. This force field was able to reproduce the structural ordering (pre-crystallization) process of polymer chains in nanocomposites [28,38,39], and to provide a coincidence with the experimental data [27,37]. The partial charges were equal to zero for two reasons: firstly, a repeating unit of BPDA-P3 does not have strong polar groups (where the significant electron density shift occurs) between which additional considerable dipole-dipole interactions can arise; secondly, we have shown previously that taking into account the partial charges in the simulation of such PEIs did not significantly affect the general character of the structural ordering of the planar PEI fragments [38]. ...
... This force field was able to reproduce the structural ordering (pre-crystallization) process of polymer chains in nanocomposites [28,38,39], and to provide a coincidence with the experimental data [27,37]. The partial charges were equal to zero for two reasons: firstly, a repeating unit of BPDA-P3 does not have strong polar groups (where the significant electron density shift occurs) between which additional considerable dipole-dipole interactions can arise; secondly, we have shown previously that taking into account the partial charges in the simulation of such PEIs did not significantly affect the general character of the structural ordering of the planar PEI fragments [38]. Moreover, as was shown in our earlier studies, qualitative agreement of simulation data with experimental data on structural and mechanical properties can also be observed when using models that do not take into account the presence of partial charges [39,40]. ...
The effect of polymer chain ordering on the transport properties of the polymer membrane was examined for the semi-crystalline heterocyclic polyetherimide (PEI) BPDA-P3 based on 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and diamine 1,4-bis [4-(4-aminophenoxy)phenoxy]benzene (P3). All-atom Molecular Dynamics (MD) simulations were used to investigate the gas diffusion process carried through the pores of a free volume several nanometers in size. The long-term (~30 μs) MD simulations of BPDA-P3 were performed at T = 600 K, close to the experimental value of the melting temperature (Tm ≈ 577 K). It was found during the simulations that the transition of the PEI from an amorphous state to an ordered one occurred. We determined a decrease in solubility for both the gases examined (CO2 and CH4), caused by the redistribution of free volume elements occurring during the structural ordering of the polymer chains in glassy state (Tg ≈ 481 K). By analyzing the diffusion coefficients in the ordered state, the presence of gas diffusion anisotropy was found. However, the averaged values of the diffusion coefficients did not differ from each other in the amorphous and ordered states. Thus, permeability in the observed system is primarily determined by gas solubility, rather than by gas diffusion.
... For instance, in our previous study [8], it was experimentally shown that the addition of 1% mass of vapor-grown carbon fiber (VGCF) and 0.1% single-walled carbon nanotube (SWCNT) leads to improved mechanical properties of PI fibers derived from the commercially available amorphous polyetherimide Ultem 1000. The enhancement of the thermophysical and mechanical characteristics of nanocomposites based on thermoplastic PIs was shown both in the experimental study and computer simulation [27,28,[37][38][39][40][41][42][43]. The reinforcement of polymers by carbon nanoparticles can lead to the initialization and acceleration of the crystal growth of PIs [27,28,[39][40][41][42][43]. ...
... The enhancement of the thermophysical and mechanical characteristics of nanocomposites based on thermoplastic PIs was shown both in the experimental study and computer simulation [27,28,[37][38][39][40][41][42][43]. The reinforcement of polymers by carbon nanoparticles can lead to the initialization and acceleration of the crystal growth of PIs [27,28,[39][40][41][42][43]. ...
... However, the question arises whether nanoparticle-induced polymer chain orientation in the melt could cause the viscosity change instead of the formation of interchain links. Furthermore, the change in viscosity based on the orientation of the carbon nanotubes and polymer matrix might be particularly essential once the material is cooled down to regulate the anisotropy of mechanical characteristics at room temperature [39,40,42,43]. It is complicated to directly determine this in the experiment because it is practically impossible to measure the rheological properties of the polymer interface close to the nanofiller in the directions along and across the surface of carbon nanoparticles. ...
Recently, a strong structural ordering of thermoplastic semi-crystalline polyimides near single-walled carbon nanotubes (SWCNTs) was found that can enhance their mechanical properties. In this study, a comparative analysis of the results of microsecond-scale all-atom computer simulations and experimental measurements of thermoplastic semi-crystalline polyimide R-BAPB synthesized on the basis of dianhydride R (1,3-bis-(3′,4-dicarboxyphenoxy) benzene) and diamine BAPB (4,4′-bis-(4″-aminophenoxy) biphenyl) near the SWCNTs on the rheological properties of nanocomposites was performed. We observe the viscosity increase in the SWCNT-filled R-BAPB in the melt state both in computer simulations and experiments. For the first time, it is proven by computer simulation that this viscosity change is related to the structural ordering of the R-BAPB in the vicinity of SWCNT but not to the formation of interchain linkage. Additionally, strong anisotropy of the rheological properties of the R-BAPB near the SWCNT surface was detected due to the polyimide chain orientation. The increase in the viscosity of the polymer in the viscous-flow state and an increase in the values of the mechanical characteristics (Young’s modulus and yield peak) of the SWCNT‑R-BAPB nanocomposites in the glassy state are stronger in the directions along the ordering of polymer chains close to the carbon nanofiller surface. Thus, the new experimental data obtained on the R-BAPB-based nanocomposites filled with SWCNT, being extensively compared with simulation results, confirm the idea of the influence of macromolecular ordering near the carbon nanotube on the mechanical characteristics of the composite material.
... As part of the laboratory's work, from 2014 until 2019 theoretical and experimental research was carried out on the properties of nanocomposites based on thermoplastic polymers of various chemical structure with the addition of carbon nanoparticles with a range of structures. The results obtained were published in the series of experimental [43,[87][88][89] and theoretical [43,88,[90][91][92][93][94][95] studies targeted at research of crystallizable polymers which, generally speaking, had the greatest potential for the industrial application of advanced thermoplastic polymers-thermoplastic PIs-in combination with a carbon nanofiller. ...
... It is of interest that the addition of carbon nanotubes can lead to crystallization in initially amorphous thermoplastic PIs [50]. With the aid of all-atom computer simulation methods, a study was made of the structure of the surface layer of the two amorphous PIs aBPDA-P3 and ODPA-P3 in proximity to SWCNTs [93]. Ordering of the flat fragments of the ODPA-P3 polymer chains was observed in proximity to the surface of the SWCNTs. ...
... In order to determine the molecular mechanism responsible for the experimentally observed initiation of crystallization of the thermoplastic PI ODPA-P3 when SWCNTs are added, a study was made of the structure of the interface of the ODPA-P3-based nanocomposite reinforced with SWCNTs [93]. The influence of two possible factors which may initiate the orientation of the polymer near the nanofiller was studied: the spatial restriction of the SWCNT surface and the influence of π-π-interactions at the "polymer-SWCNT" interface. ...
The following review focuses on the analysis of computer simulation and experimental research of the initial crystallization stage of crystallizable thermoplastic polyimides, which have a strong potential as bonding agents in the creation of new advanced materials with improved performance. It has been demonstrated that the introduction of carbon nanofillers has a significant influence on the initiation of polyimide crystallization and on the properties of the polymer matrix. The review also discusses the molecular mechanisms which are responsible for the improved mechanical properties of nanocomposites based on crystallizable polyimides.
... PAI has not only a hydrogen-bond interaction with the surface of oxidized CF and electrostatic interactions with MXene introduced rich functional groups (-OH, -O, -F), but also a similar benzene ring to display the π-π interaction with PEEK in the interface interaction [30]. Hydroxyl groups of CF and MXene provide electrostatic interactions with five-membered rings of PAI [33]. The two-dimensional structure of MXene in combination with electronegative surfaces and active functional groups endow it with electrostatic properties. ...
Thermoplastic resins have contributed more and more to the field of fiber reinforced composites. The ability to fabricate fiber reinforced thermoplastic resin composites with excellent and functional interface performances has so far been elusive. Herein, we use a polyamide-imide (PAI)/Ti3C2Tx MXene sizing to enhance the interfacial performance of CF reinforced polyetheretherketone (PEEK) composites. The composite sizing makes the composite with high interfacial adhesion and electromagnetic interference (EMI) shielding performances. Our results indicate that traditional composite materials can improve performance and increase functionality through interface treatment.
... 21 In a series of papers, Lyulin and collaborators have performed all-atom MD simulations on a range of polytherimides, including those based on the dianhydride R and various diamines (e.g., BAPS, BAPO, and BAPB), 22−25,28−30 Ultem and Extem (a polyetherimide based on the BPADA dianhydride and DDS diamine), 26,27 and the ODPA-P3 polyetherimide and BPDA-P3 and aBPDA-P3 polyimides based on the P3 diamine. 31 They have demonstrated a twostep protocol that allows microsecond all-atom MD simulations for polymer equilibration, 22,23 computed the thermal properties of bulk R-BAPS and Extem, 24 and identified the ordering behavior of R-BAPS and R-BAPB at the surface of a single-walled CNT 25 and a graphene sheet. 28 They also investigated the influence of electrostatic interactions on the thermophysical properties of Ultem and Extem 26,27 and R-BAPS. ...
... 29 Furthermore, they simulated the mechanical deformation and computed the elastic moduli of various polyimides. 30, 31 Minelli combined MD simulations and perturbed chain statistical associating fluid theory to predict the solubility of various gases in Ultem and Kapton (a PMDA-ODA polyimide). 32 Lim et al. simulated the diffusion and sorption of CO 2 and CH 4 in amorphous Ultem and a CNT-Ultem composite. ...
... [21] In a series of papers, Lyulin and collaborators have performed all-atom MD simulations on a range of polytherimides, including those based on the dianhydride R and various diamines (e.g., BAPS, BAPO, and BAPB), [22][23][24][25][28][29][30], Ultem and Extem (a polyetherimide based on the BPADA dianhydride and DDS diamine) [26,27], and the ODPA-P3 polyetherimide and BPDA-P3 and aBPDA-P3 polyimides based on the P3 diamine. [31] They have demonstrated a two-step protocol that allows microsecond all-atom MD simulations for the equilibration of polyimides, [22,23] computed the thermal properties of bulk R-BAPS and Extem, [24] and identified the ordering behavior of R-BAPS and R-BAPB at the surface of a single-walled CNT [25] and a graphene sheet. [28] They also investigated the influence of electrostatic interactions on the thermophysical properties of Ultem and Extem [26,27] and R-BAPS. ...
... [29] Furthermore, they simulated the mechanical deformation and computed the elasticity modulus of various polyimides. [30,31] Minelli combined MD simulations and the perturbed arXiv:2006.08715v1 [cond-mat.mtrl-sci] ...
A coarse-grained model is developed to allow large-scale molecular dynamics simulations of a branched polyetherimide derived from two backbone monomers [4,4'-bisphenol A dianhydride (BPADA) and m-phenylenediamine (MPD)], a chain terminator [phthalic anhydride (PA)], and a branching agent [tris[4-(4-aminophenoxy)phenyl] ethane (TAPE)]. An atomistic model is first built for the branched polyetherimide. A systematic protocol based on chemistry-informed grouping of atoms, derivation of bond and angle interaction by fitting bond and angle distributions to Gaussian functions, and parameterization of nonbonded interactions by potential of mean force (PMF) calculations, is used to construct the coarse-grained model. A six-pair geometry, with one atomic group fixed at center and six replicates of another atomic group placed surrounding the central group in a NaCl structure, has been demonstrated to significantly speed up the PMF calculations. Furthermore, we propose a universal entropic correction term to the PMFs that can make the resulting coarse-grained model transferable temperature-wise, by enabling the model to capture the thermal expansion property of the polymer. The coarse-grained model has been applied to explore the mechanical, structural, and rheological properties of the branched polyetherimide.
... It should be noted that recently the GROMOS force eld was successfully used to model the initial stages of crystallization in polyimide and polyetherimide nanocomposite materials. 72,73 The lack of crystallization which is observed in our study for GROMOS eicosane samples could be due to excessively high cooling rates employed (see below). A difference in the chemical structure of the polymers also could play role. ...
Paraffin-based composites represent a promising class of materials with numerous practical applications such as e.g. heat storage. Computer modeling of these complex multicomponent systems requires a proper theoretical description of both the n-alkane matrix and the non-alkane filler molecules. The latter can be modeled with the use of a state-of-the-art general-purpose force field such as GAFF, CHARMM, OPLS-AA and GROMOS, while the paraffin matrix is traditionally described in the frame of relatively old, alkane-specific force fields (TraPPE, NERD, and PYS). In this paper we link these two types of models and evaluate the performance of several general-purpose force fields in computer modeling of paraffin by their systematic comparison with earlier alkane-specific models as well as with experimental data. To this end, we have performed molecular dynamics simulations of n-eicosane bulk samples with the use of 10 different force fields: TraPPE, NERD, PYS, OPLS-UA, GROMOS, GAFF, GAFF2, OPLS-AA, L-OPLS-AA, and CHARMM36. For each force field we calculated several thermal, structural and dynamic characteristics of n-eicosane over a wide temperature range. Overall, our findings show that the general-purpose force fields such as CHARMM36, L-OPLS-AA and GAFF/GAFF2 are able to provide a realistic description of n-eicosane samples. While alkane-specific models outperform most general-purpose force fields as far as the temperature dependence of mass density, the coefficient of volumetric thermal expansion in the liquid state, and the crystallization temperature are concerned, L-OPLS-AA, CHARMM36 and GAFF2 force fields provide a better match with experiment for the shear viscosity and the diffusion coefficient in melt. Furthermore, we show that most general-purpose force fields are able to reproduce qualitatively the experimental triclinic crystal structure of n-eicosane at low temperatures.
... This force field belongs to the open-source force fields of the class I and is native for Gromacs [55] software package, which is perfectly suited for performing computationally demanding microsecond timescale all-atom molecular dynamics simulations. As it was shown previously, Gromos53a6 may be successfully used to simulate thermophysical, mechanical, and relaxation properties of various thermoplastic polyimides, and even the initial stages of their crystallization in the presence of the carbon nanoparticles [43][44][45][46][56][57][58][59]. ...
... Another important issue is related to accounting for Coulomb interactions in the system due to the presence of partial charges on the atoms of both the gases and the polymer [44,64]. As previously demonstrated, Coulomb interactions can lead to a sharp decrease in both the translational and segmental mobility of polymer chains, even at high temperatures (~600 K) [56][57][58][59]. It suggests that longer simulations are needed to determine the diffusion coefficients of gases in polymer, especially at room temperature, something which is currently beyond the power of modern supercomputers. ...
The present work evaluates the transport properties of thermoplastic R-BAPB polyimide based on 1,3-bis(3,3′,4,4′-dicarboxyphenoxy)benzene (dianhydride R) and 4,4′-bis(4-aminophenoxy)biphenyl (diamine BAPB). Both experimental studies and molecular dynamics simulations were applied to estimate the diffusion coefficients and solubilities of various gases, such as helium (He), oxygen (O2), nitrogen (N2), and methane (CH4). The validity of the results obtained was confirmed by studying the correlation of the experimental solubilities and diffusion coefficients of He, O2, and N2 in R-BAPB, with their critical temperatures and the effective sizes of the gas molecules, respectively. The solubilities obtained in the molecular dynamics simulations are in good quantitative agreement with the experimental data. A good qualitative relationship between the simulation results and the experimental data is also observed when comparing the diffusion coefficients of the gases. Analysis of the Robeson plots shows that R-BAPB has high selectivity for He, N2, and CO2 separation from CH4, which makes it a promising polymer for developing gas-separation membranes. From this point of view, the simulation models developed and validated in the present work may be put to effective use for further investigations into the transport properties of R-BAPB polyimide and nanocomposites based on it.
... More importantly, for PEI-MWCNT-CF, the concentrations of hydroxyl groups (-OH), carboxyl groups ( -COOH) and carbonyl group (-C--O) were increased compared with PEI-CF. Hydroxyl groups provides electrostatic interactions with five-membered rings in PEI [25]; carboxyl groups may form hydrogen bonding with PEI. This indicated that the functionalized MWCNTs might incorporate into the surface of the prepared PEI membranes. ...
Due to the extraordinary thermal stability, chemical resistance and processability, carbon fiber (CF) reinforced polyetheretherketone (PEEK) composites are widely applied in aviation, aerospace, medical fields, etc. However, the non-polar nature and low wettability of CFs limited the interfacial bonding between CFs and PEEK and results in unsatisfied mechanical properties for CF/PEEK composites. In order to enhance interactions between fibers and matrix, the interface in CF/PEEK composites was built through coating a mixture of polyetherimide (PEI) and functionalized multi-walled carbon nanotubes (COOH-MWCNTs) on CFs. The combination of hydrogen bonding between COOH-MWCNT and PEI as well as the π-π interaction between PEI and PEEK significantly improved the miscibility and interfacial interlocking. As a result, the flexural strength, modulus and interlaminar shear strength (ILSS) of modified CF/PEEK were remarkably improved by 76% (667.8 MPa), 119% (40.0 GPa), and 85% (90.7 MPa) respectively. The failure mechanism changed from smooth cracking in interface destruction to zigzag cracking and resin breakage, suggesting that the resultant interface became strong enough to ensure efficient stress transfer from PEEK to CF. The synergistic interfacial interactions via hydrogen bonding and pi-pi stacking are believed to supply an effective strategy for building high-performance thermoplastic composites
