Bulk Polymer Research Articles

A Multiscale Hollow Spherical LATP Active Filler Improves Conductivity and Mechanical Strength in Composite Solid Electrolytes

The performance of composite solid electrolytes (CSEs) composed of poly(ethylene oxide) and ceramic oxide-type solid electrolyte fillers has been shown to be highly dependent on the available surface area of filler inside of the composite. This is due to the formation of new transport pathways in the polymer-ceramic interphase, a region some tens of nanometers between the bulk polymer and ceramic surface. The small volume of this interphase relative to the size of traditional particles presents a design problem: Using micron-scale filler particles, a nm-thick interphase can never occupy a meaningful volume fraction of the composite. Thus, nanoparticles are often used in CSEs. However, the inevitable agglomeration of nanoparticles prevents a continuous interphase from forming even in the best dispersion conditions. Therefore, efforts to explore and exploit this synergistic transport mechanism have so far relied on careful, slow, and expensive methods designed to yield a continuous polymer-ceramic interphase between electrodes, e.g., cast nanowires, infiltrated 3D-structures, or templating.In this work we report a ceramic solid electrolyte, Li1.3Al0.3Ti1.7(PO4)3 or LATP, with a multiscale hollow spherical microstructure, designed to maximize the available continuous interphase volume in the composite. The hollow spherical structure is achieved by synthesizing LATP particles onto 10-15 μm carbon spheres, then subsequently pyrolyzing the carbon to achieve micron-scale hollow spheres composed of nano-scale LATP particles. This structure effectively prevents the bulk agglomeration of individual LATP particles, while still allowing for long, continuous interphase pathways. Importantly, the non-directionality of the filler means that the manufacture of the films remains simple.The hollow spherical microstructure of the filler had significantly enhanced the room temperature conductivity of the composite solid electrolyte, to 1.64 x 10-4 S/cm – the highest reported for an LATP-containing CSE with micron-scale filler particles. The mechanical properties, thermal stability, and electrochemical stability of the composite solid electrolyte were also significantly enhanced. This approach is a promising method to exploiting the synergistic transport in composite solid electrolytes while maintaining their excellent manufacturability.

Understanding Polymer Structure and Conductivity in Composite Electrolytes

Lithium ion batteries are a crucial technologies for electric vehicles and portable electronics due to their high energy density. However, flammable liquid electrolytes create a safety concern and transitioning to all solid state batteries allows for the potential of higher energy density by utilizing lithium metal anodes. Two classes of solid materials have been explored to replace liquid electrolytes: ceramic and polymer electrolytes. Composite electrolytes, typically in the form of dispersed ceramic particles or nanowires in polymer matrix, combine these two materials to have good ionic conductivity while maintaining the mechanical properties of the polymer. While they have achieved fairly high conductivity (typically 10-4 S/cm), the mechanism for such ion conduction is not well understood.The polymer likely plays a crucial role as the ceramic volume fractions are typically under 20%.1,2 Four possible ways that polymers could increase in conductivity in the composite have been identified: decreased crystallinity, increased free volume, disruption of polymer alignment, and increased lithium ion dissolution due to acidic surface groups on the ceramic.1,3,4 We have developed thin film model systems to probe the interface of the polymer with and ceramic surfaces. We found that when confined to thin films, the conductivity of the polymer electrolyte increased compared to the bulk. We utilized differential scanning calorimetry to identify the crystallinity and found that the small crystallinity variation could not account for the variation in conductivity. Subsequently, we utilized surface conductivity and transference number measurements to understand the effects of acidic surface groups. X-ray Absorption measurements will be similarly utilized to probe the variation in lithium ion environments within these materials to understand any variation in the lithium salt dissolution. It was found that the variation in conductivity based on this effect is small.In order to probe the possible variation in free volume, Small Angle Neutron Scattering will be utilized to quantify the free volume within thin films, bulk polymer, and composite electrolytes. This can quantify the volume associated with each monomer and therefore how much space is between polymer chains for lithium ion movement.5 Lastly, while the polymer chain alignment has not been extensively discussed composite literature, it has been identified that when polymer electrolytes are cast on a surface, polymer electrolytes typically show anisotropy with measurements parallel to the surface having higher conductivity due to the alignment of the chain.6 Therefore, ceramic fillers in the composites may disrupt this packing and allow for higher conductivity perpendicular to the cast surface, the direction in which they are most commonly measured. In order to probe this effect, we measure the anisotropy of both our thin film electrolytes as well as composite electrolytes to compare the significance of the anisotropy and utilize small angle x-ray scattering to measure any anisotropy in the structure.

Group transfer polymerization in bulk methacrylates

AbstractGroup transfer polymerization (GTP) is a polymerization method developed to obtain targeted (meth)acrylic polymers in solution at ambient temperatures. In this work, it is employed with methacrylic monomers to obtain low Ð polymers in bulk. In this regard, different initiator systems that exhibit different mechanisms are compared concerning the molecular weight, the polydispersity and double bond conversion of the resulting bulk polymers. The respective systems were chosen carefully to give a broad overview of earlier developed initiator‐catalyst combinations 1‐methoxy‐1‐(trimethylsiloxy)‐2‐methylprop‐1‐ene (MTS) & tetrabutylammonium cyanide (TBACN) and more recently investigated initiating systems MTS & trityl tetrakis(pentafluorophenyl)borate (TTPB) or dimethyl phenyl silane (DMPS) & tris(pentafluorophenyl)borate (BCF). The described initiating systems are applied as a two‐component (2K) system to ensure a homogeneous distribution of the respective initiator and catalyst in the bulk monomer. In addition to the 2K experiments, photochemical initiation is also applied to bulk formulations. Therefore, a photoacid generator (PAG) and MTS is used to trigger the polymerization reaction by irradiation with UV light. A highly controlled photopolymerization method in bulk was developed that way achieving a low polydispersity polymer with high double bond conversion.

Glass transition temperature of (ultra-)thin polymer films.

The glass transition temperature of confined and free-standing polymer films of varying thickness is studied by extended molecular dynamics simulations of bead-spring chains. The results are connected to the statistical properties of the polymers in the films, where the chain lengths range from short, unentangled to highly entangled. For confined films, perfect scaling of the thickness-dependent end-to-end distance and radius of gyrations normalized to their bulk values in the directions parallel and perpendicular to the surfaces is obtained. In particular, the reduced end-to-end distance in the perpendicular direction is very well described by an extended Silberberg model. For bulk polymer melts, the relation between the chain length and Tg follows the Fox-Flory equation. For films, no further confinement induced chain length effect is observed. Tg decreases and is well described by Keddie's formula, where the reduction is more pronounced for free-standing films. It is shown that Tg begins to deviate from bulk Tg at the characteristic film thickness, where the average bond orientation becomes anisotropic and the entanglement density decreases.

Plasma treatment process for accelerating the disintegration of a biodegradable mulch film in soil and compost

Biodegradable Mulch Films (BMFs) offer a sustainable alternative to traditional non-degradable (Polyethylene) PE mulch films. However, their slow rate of biodegradation can lead to plastics accumulation in soil. In this study, a commercially available BMF based on poly (butylene adipate co-terephthalate) (PBAT) and poly (lactic acid) (PLA) is examined. Here the effects of gliding arc plasma treatment on the bulk and surface properties, as well as its degradation behavior in soil and compost is studied. An increase in surface oxygen containing species and hydrophilicity was observed following plasma treatment. Only a small hydrophobic recovery was noted over 30 days. No changes in the bulk polymer molecular weight or thermal properties following treatment were noted. However, a decrease in mechanical strength was observed following gliding arc plasma treatment. The onset of film fragmentation in both soil and compost occurred earlier for a plasma treated film and we attribute this to an improvement in the initial adhesion of bacteria on the surface.

The effect of cold glow discharge nitrogen plasma treatment of sisal fiber (Agave Sisalana) on sisal fiber reinforced epoxy composite

PurposeThe incompatibility of natural fibers with polymer matrices is one of the key obstacles restricting their use in polymer composites. The interfacial connection between the fibers and the matrix was weak resulting in a lack of mechanical properties in the composites. Chemical treatments are often used to change the surface features of plant fibers, yet these treatments have significant drawbacks such as using substantial amounts of liquid and chemicals. Plasma modification has recently become very popular as a viable option as it is easy, dry, ecologically friendly, time-saving and reduces energy consumption. This paper aims to explore plasma treatment for improving the surface adhesion characteristics of sisal fibers (SFs) without compromising the mechanical attributes of the fiber.Design/methodology/approachA cold glow discharge plasma (CGDP) modification using N2 gas at varied power densities of 80 W and 120 W for 0.5 h was conducted to improve the surface morphology and interfacial compatibility of SF. The mechanical characteristics of unmodified and CGDP-modified SF-reinforced epoxy composite (SFREC) were examined as per the American Society for Testing and Materials standards.FindingsThe cold glow discharge nitrogen plasma treatment of SF at 120 W (30 min) enhanced the SFREC by nearly 122.75% superior interlaminar shear strength, 71.09% greater flexural strength, 84.22% higher tensile strength and 109.74% higher elongation. The combination of improved surface roughness and more effective lignocellulosic exposure has been responsible for the increase in the mechanical characteristics of treated composites. The development of hydrophobicity in the SF had been induced by CGDP N2 modification and enhanced the size of crystals and crystalline structure by removing some unwanted constituents of the SF and etching the smooth lignin-rich surface layer of the SF particularly revealed via FTIR and XRD.Research limitations/implicationsChemical and physical treatments have been identified as the most efficient ways of treating the fiber surface. However, the huge amounts of liquids and chemicals needed in chemical methods and their exorbitant performance in terms of energy expenditure have limited their applicability in the past decades. The use of appropriate cohesion in addition to stimulating the biopolymer texture without changing its bulk polymer properties leads to the formation and establishment of plasma surface treatments that offer a unified, repeatable, cost-effective and environmentally benign replacement.Originality/valueThe authors are sure that this technology will be adopted by the polymer industry, aerospace, automotive and related sectors in the future.

Mechanism of coupling polymer thickness and interfacial interactions on strength and toughness of non-covalent nacre-inspired graphene nanocomposites

Nanoconfinement resulting from interfacial attraction leads to the formation of polymer interphases with outstanding stiffness, which profoundly impacts the toughness and strength of non-covalent nacre-inspired nanocomposites with “brick-and-mortar” structures. Nonetheless, challenges arise due to discrepancies in interphase thickness characterization and ambiguity in nanoscopic foundations of interfacial stiffening, which hinders systematic understanding of strengthening and toughening mechanisms. To address these issues, we conduct coarse-grained molecular dynamics simulations to investigate the effect of polymer phase thickness and interfacial strength on the toughness and strength of graphene-polyethylene nanocomposites. Our results indicate that when the interfacial adhesion is equal to 0.12 J/m2, nanocomposites possessing a polyethylene phase thickness of 3 nm exhibit significantly greater yield strength (590.8 ± 3.3 MPa) than those of other thicknesses, while nanocomposites with polyethylene phase thickness of 13 nm exhibit the highest toughness (83.3 ± 1.7 MJ/m3). When the interfacial interaction adhesion increases from 0.12 to 1.75 J/m2, both the yield strength and toughness of nanocomposites with polymer thickness 3 nm experience a three-phase increase, reaching up to 1442.3 ± 107.7 MPa and 119.8 ± 8.4 MJ/m3, respectively. The aforementioned improvement in both strength and toughness can be attributed to the nanoconfinement originating from strong interfacial adhesion, which enhances the stiffness and strength of the polymer glues filling the gaps of graphene “bricks”. Furthermore, the deviation of the simulation results from the shear-lag model with mechanical properties of bulk polymer can be remedied with the nanoconfinement effect and polymer stretch taken into account. Our findings provide timely guidance for future design of non-covalent nacre-inspired graphene-based polymer nanocomposites with high toughness and strength.

Interphase in polymer-based nanocomposites: Polyoctenamer – Single-walled carbon nanotubes

A detailed and critical analysis of the non-isothermal thermogravimetric analysis of polyoctenamer-single wall carbon nanotube, is presented. The thermogravimetric data were obtained under an inert atmosphere (nitrogen) on polyoctenamer- single wall carbon nanotube nanocomposites loaded by different amounts of nanofiller (up to 10 % wt. single wall carbon nanotube), at various heating rates ranging from 5 to 40 °C/minute.The research focuses on the identification of the polymer-nanofiller interphase, including the detailed dissemination between the interface and interphase. The manuscript aims at the information that can be extracted from the recorded thermograms as well as from the derivatives of the thermograms with respect to the temperature. The detailed analysis of the temperature at which x% of the mass is volatilized, TX%, and of the residual mass fraction at high temperatures (850 °C and 950 °C) provide qualitative support for the presence of interphase.The research demonstrated that the derivatives of the thermograms versus temperature have a better resolution than “standard” thermograms. The derivative of the thermograms provides qualitative information about the formation of an interphase. A model for the degradation of the nanocomposites is proposed by assuming that the dependence of the inflection temperature on the composition of the nanocomposite obeys a Fox-like dependence, where the bulk polymer and the polymer trapped within the interphase are considered as a blend of two miscible polymers.

Hydrocracking of surgical face masks over Y Zeolites: Catalyst development, process design and life cycle assessment

This study highlights the hydrocracking route for the management of surgical face masks, made of polypropylene, into liquid fuels. Hydrocracking experiments were performed at 325 ℃ and 10 bar cold H2 pressure over Ni-loaded HY and steamed HY zeolites. Ni-loaded steamed Y zeolite demonstrated to be the best catalyst leading to considerably high conversion (100 wt%) and selectivity to liquids (85.5 wt%). The increase in the external surface area and mesoporous volume that improved the bulk polymer molecules diffusion, combined with the uniformly dispersed Ni particles and the additionally generated Lewis acidity, were at the origin of the observed behaviour. This catalyst also showed reasonable stability and ability to be thermally regenerated. From the environmental perspective, life cycle assessment shows the benefits of hydrocracking over pyrolysis and incineration.Therefore, our results demonstrate that Ni-loaded steamed Y zeolites could be promising catalysts for the upcycling of surgical face masks to gasoline range fuels, with minimum environmental impacts.

Pressure of Linear and Ring Polymers Confined in a Cavity.

Nanoscale confinement of polymers in a cavity is central to a variety of biological and nanotechnology processes. Using the discrete WLC model we simulate the compression of flexible and semiflexible polymers of linear and ring topology in a closed cavity. Simulation reveals that polymer pressure inside the cavity increases with the chain stiffness but is practically unaffected by the chain topology. For flexible polymers, the computed dependence of pressure on the cavity size and polymer concentration is consistent with the scaling behavior expected for bulk polymers in a good solvent. However, the scaling behavior of semiflexible polymers is only in partial agreement with the theory prediction, with discrepancies arising from a continuous transition between regimes in chains of moderate lengths. The computed segment density profiles endorse the propensity of semiflexible polymers to concentrate beneath the cavity surface and thus elevate the pressure. The compaction of polymers by compression into the disordered globule or growing toroidal structure is documented.

Responsive polymer thin films

Responsive polymer thin films

Effect of polymer architecture on the adsorption behaviour of amphiphilic copolymers: A theoretical study

HypothesisPolymer architecture is known to have significant impact on its adsorption behaviour. Most studies have been concerned with the more concentrated, “close to surface saturation” regime of the isotherm, where complications such as lateral interactions and crowding also additionally affect the adsorption. We compare a variety of amphiphilic polymer architectures by determining their Henry’s adsorption constant (kH), which, as with other surface active molecules, is the proportionality constant between surface coverage and bulk polymer concentration in a sufficiently dilute regime. It is speculated that not only the number of arms or branches, but also the position of adsorbing hydrophobes influence the adsorption, and that by controlling the latter the two can counteract each other. MethodologyThe Self-consistent field calculation of Scheutjens and Fleer was implemented to calculate the adsorbed amount of polymer for many different polymer architectures including linear, star and dendritic. Using the adsorption isotherms at very low bulk concentrations, we determined the value of kH for these. FindingsIt is found that the branched structures (star polymers and dendrimers) can be viewed as analogues of linear block polymers based on the location of their adsorbing units. Polymers containing consecutive trains of adsorbing hydrophobes in all cases showed higher level of adsorption compared to their counterparts, where the hydrophobes were more uniformly distributed on the chains. While increasing the number of branches (or arms for star polymers) also confirmed the known result that the adsorption decreased with the number of arms, this trend can be partially offset by the appropriate choice of the location of anchoring groups.

Single-Chain Mechanics at Low Temperatures: A Study of Three Kinds of Polymers from 153 to 300 K

The single-chain mechanics of three kinds of polymers (i.e., polydimethylsiloxane, polyoxymethylene, and poly(methyl methacrylate)) has been investigated from room temperature to 153 K by atomic force microscopy-based single-molecule force spectroscopy in high vacuum and a theoretical model. The stretched part of the individual polymer chain can be regarded as an isolated chain. In the broad range of temperature, the isolated chain shows a gradual change in single-chain mechanics, which can be depicted nicely by an elastic model. Further analysis shows that with thermal fluctuation, the single bonds (e.g., Si–O or C–O) in the backbone of an isolated chain can rotate freely in the temperature range in the timescale of single-molecule manipulation. To our best knowledge, this is the first experimental study on the single-chain mechanics at cryogenic temperatures, which validates the theoretical prediction that the transition temperature of an isolated chain is much lower than that of the corresponding bulk polymer material.

Parametric extraction and internal analysis of fullerene-based polymer bulk heterojunction solar cell

This paper present device model simulation describing the current-voltage characteristics of polymer/fullerene bulk heterojunction solar cell. In the research paper an organic photovoltaic device with PPV/PCBM [poly (2-methoxy-5-{3’,7’-dimethyloctyloxy}-p-phenylene vinylene) and {6,6}- phenyl C61-butyric acid methyl ester] was simulated via Silvaco TCAD 2-D simulation tool. PCBM acts as acceptor and PPV is donor. The models used to simulate the device were Langevin for recombination, s.binding and a.singlet. Simulation of these type of devices is an vital approach to project and predict the cell performance. Under the illumination of one sun (AM 1.5) the simulated organic cell showed a short circuit current density (JSC) of 28 A/m2, open circuit voltage (VOC) of 0.84 Volt and a fill factor (FF) of 52.51%, the resulting maximum efficiency of the PPV/PCBM organic solar cell is 1.22%.

Self-consistent Sierpinski iteration of toughening mechanism in elastomer undergoing scaled segment-chain-network

Understanding working principles and toughening mechanisms of soft elastomers has been a huge challenge due to their significant scaling effects from molecules to bulk polymer. In this study, by combining Sierpinski fractal and scaling theory, an extended Kelvin model is developed to investigate the mechanical behaviour of the soft elastomer undergoing scaled segment-chain-network. According to the scaling theory, a radial distribution function was initially introduced to explain the diffusion and relaxation behaviours of molecular segments with the Sierpinski fractal features. The self-consistent iteration of the Sierpinski fractal is then used to describe the scaling effects of segments and networks. Rubber elasticity of the polymer network is further formulated based on the self-consistent iteration equation and scaling theory. A constitutive stress–strain relationship is also derived to explore the toughness mechanism and working principle in the polymer elastomer. Finally, the effectiveness of the proposed model is verified using finite-element analysis and experimental results reported in the literature, to explore a scaling insight into toughening mechanisms of elastomers governed by the self-consistent Sierpinski iteration.

Thermomechanical characteristics of green nanofibers made from polylactic acid: An insight into tensile behavior via molecular dynamics simulation

All-atom molecular dynamics simulations are conducted to elucidate the thermomechanical characteristics of polylactic acid nanofibers with a diameter range of 1.93 nm–5.4 nm. Nanofibers undergo tensile deformations from which elastic, yield, softening and fracture phases are recognized and mechanical parameters are evaluated by tracking the stress, energy and geometrical evolutions at each phase. Special attention is devoted to the fracture phase where a new method is proposed to calculate the energy release rate during crack propagation which is a crucial factor in fracture mechanics. The effect of nanofibers' diameter, temperature and the deformation strain rate on fracture properties, moduli of resilience and toughness, yield stress, Young's modulus and Poisson's ratio is studied. Monitoring the variation of the internal energy components during deformation reveals the dominance of bond and van der Waals contributions in the deformation mechanism. Finally, a comparison of nanofiber parameters with that of the bulk polymer shows that compared to the thermal properties, the mechanical parameters are more affected by the confinement of the nanofibers.

Shish-kebab crystallites initiated by shear fracture in bulk polymers: 2. Crystallization on shearing

Shish-kebab crystallites are initiated by the oriented precursors of the ordered structures in the flow processing of polymer materials. In our previous work, we have proposed that the sporadic local events of shear fracture and their memory are responsible for the heterogeneous initiation of shish-kebab crystallites in the shear flow of bulk polymers. Upon the cessation of the Poiseuille-flow-like force field in the binary polymer blends of two chain lengths, our dynamic Monte Carlo simulations demonstrated the formation of precursor and shish-kebab crystal structure at a low temperature. In the present work, we further investigated the boundary conditions of precursor formation at low temperatures while maintaining the force gradients reflecting the global shear rates. The phase diagram of morphological features upon the variations of temperatures and force gradients reveals that steady shish precursors survive at higher temperatures and larger force gradients than the region for shish-kebab crystallites, appearing as responsible for the subsequent shish-kebab formation upon cooling with or without shear cessation. The results are consistent with the related experimental observations and evidence the pre-ordering structure existing before shear-induced polymer crystallization.

A first-principles study of 1D and 2D C60 nanostructures: strain effects on band alignments and carrier mobility

In the breakthrough progress made in the latest experiment Hou et al (2022 Nature 606 507), 2D polymer was exfoliated from the quasi-hexagonal bulk crystals. Bulk polymer with quasi-tetragonal phase was found to easily form 1D fullerene structure with molecules connected by C=C. Inspired by the experiment, we investigate the strain behaviors of 1D and 2D polymers by first-principles calculations. Some physical properties of these low dimensional polymers, including structural stability, elastic behavior, band alignment and carrier mobility, are predicted. Compared with fullerene molecule, 1D and 2D polymers are metastable. At absolute zero temperature, 1D bears a uniaxial tensile strain less than 11.5%, and 2D monolayer withstands a biaxial tensile strain less than 7.5%. At 300 K, ab initio molecular dynamics confirm that they can withstand the strains of 9% and 5%, respectively. Strain engineering can adjust the absolute position of the band edge. In the absence of strain, carrier mobility is predicted to be µ e = 398 and µ h = 322 for 1D polymer, and = 34 and = 1487 for 2D polymer. Compared with other carbon based semiconductors, these polymers exhibit high effective mass, resulting in low mobility.

Probing Interfacial Behavior and Antifouling Activity of Adsorbed Copolymers at Solid/Liquid Interfaces.

Polymers containing poly(ethylene glycol) (PEG) units can exhibit excellent antifouling properties, which have been proposed/used for coating of biomedical implants, separation membranes, and structures in marine environments, as well as active ingredients in detergent formulations to avoid soil redepositioning in textile laundry. This study aimed to elucidate the molecular behavior of a copolymer poly(MMA-co-MPEGMA) containing antiadhesive PEG side chains and a backbone of poly(methyl methacrylate), at a buried polymer/solution interface. Polyethylene terephthalate (PET) was used as a substrate to model polyester textile surfaces. Sum frequency generation (SFG) vibrational spectroscopy was applied to examine the interfacial behavior of the copolymer at PET/solution interfaces in situ and in real time. Complementarily, copolymer adsorption on PET and subsequent antiadhesion against protein foulants were probed by quartz-crystal microbalance experiments with dissipation monitoring (QCM-D). Both applied techniques show that poly(MMA-co-MPEGMA) adsorbs significantly to the PET/solution interface at bulk polymer solution concentrations as low as 2 ppm, while saturation of the surface was reached at 20 ppm. The hydrophobic MMA segments provide an anchor for the copolymer to bind onto PET in an ordered way, while the pendant PEG segments are more disordered but contain ordered interfacial water. In the presence of considerable amounts of dissolved surfactants, poly(MMA-co-MPEGMA) could still effectively adsorb on the PET surface and remained stable at the surface upon washing with hot and cold water or surfactant solution. In addition, it was found that adsorbed poly(MMA-co-MPEGMA) provided the PET surface with antiadhesive properties and could prevent protein deposition, highlighting the superior surface affinity and antifouling performance of the copolymer. The results obtained in this work demonstrate that amphiphilic copolymers containing PMMA anchors and PEG side chains can be used in detergent formulations to modify polyester surfaces during laundry and reduce deposition of proteins (and likely also other soils) on the textile.

Nonlinear dynamical performance of microsize piezoelectric bridge-type energy harvesters based upon strain gradient-based meshless collocation approach

In the current exploration, the size-dependent nonlinear dynamical performance of piezoelectric bridge-type energy harvesters at microscale is analyzed. The proposed microbeam-type energy harvesters are made of a lightweight agglomerated nanocomposite polymeric passive bulk reinforced with carbon nanotubes (CNTs) and integrated with piezoelectric facesheets. In order to perform a highly accurate analysis, the modified strain gradient continuum elasticity is adopted within the framework of the quasi-3D beam theory incorporating various microstructural-dependent strain gradient tensors. Thereafter, the size-dependent nonlinear coupled electromechanical differential equations are solved numerically via employing the meshless collocation technique using a combination of the radial basis and polynomial basis functions to avoid any possible singularity. It is demonstrated that by increasing the amount of CNTs inside clusters, the effect of strain gradient tensors on the reduction in the value of induced deflection in microsized energy harvester decreases from 25.57% to 22.65% for simply supported boundary conditions, and from 33.96% to 31.56% for clamped boundary conditions. Also, the average of achieved voltage by the microsized energy harvesters increases from 245.1 mv to 262.8 mv for simply supported boundary conditions, and from 79.5 mv to 96.7 mv for clamped boundary conditions.