Electrical Percolation Research Articles

PMMA/SWCNT Composites with Very Low Electrical Percolation Threshold by Direct Incorporation and Masterbatch Dilution and Characterization of Electrical and Thermoelectrical Properties.

In the present study, Poly(methyl methacrylate) (PMMA)/single-walled carbon nanotubes (SWCNT) composites were prepared by melt mixing to achieve suitable SWCNT dispersion and distribution and low electrical resistivity, whereby the SWCNT direct incorporation method was compared with masterbatch dilution. An electrical percolation threshold of 0.05-0.075 wt% was found, the lowest threshold value for melt-mixed PMMA/SWCNT composites reported so far. The influence of rotation speed and method of SWCNT incorporation into the PMMA matrix on the electrical properties and the SWCNT macro dispersion was investigated. It was found that increasing rotation speed improved macro dispersion and electrical conductivity. The results showed that electrically conductive composites with a low percolation threshold could be prepared by direct incorporation using high rotation speed. The masterbatch approach leads to higher resistivity values compared to the direct incorporation of SWCNTs. In addition, the thermal behavior and thermoelectric properties of PMMA/SWCNT composites were studied. The Seebeck coefficients vary from 35.8 µV/K to 53.4 µV/K for composites up to 5 wt% SWCNT.

Quantum Mechanical Study of the Dielectric Response of V2C-ZnO/PPy Ternary Nanocomposite for Energy Storage Application

With the proliferation of electronic gadgets and the internet of things comes a great need for lightweight, affordable, sustainable, and long-lasting power devices to combat the depletion of fossil fuel energy and the pollution produced by chemical energy storage. The use of high-energy-density polymer/ceramic composites is generating more curiosity for future technologies, and they require a high dielectric constant and breakdown strength. Electric percolation and Interface polarization are responsible for the high dielectric constant. To create composite dielectrics, high-conductivity ceramic particles are combined with polymers to improve the dielectric constant. In this work, ternary nanocomposites with better dielectric characteristics are created using a nanohybrid filler of V2C Mxene-ZnO in a polypyrrole (PPy) matrix. Then, the bonding and the uneven charge distribution in the ceramic/ceramic contact area are investigated using quantum mechanical calculations. This non-uniform distribution of charges is intended to improve the ceramic/ceramic interface’s dipole polarization (dielectric response). The interfacial chemical bond formation can also improve the hybrid filler’s stability in terms of structure and, consequently, of the composite films. To comprehend the electron-transfer process, the density of state and electron localization function of the ceramic hybrid fillers are also studied. The polymer nanocomposite is suggested to provide a suitable dielectric response for energy storage applications.

Enhanced electrical and electromagnetic interference shielding performance of immiscible poly(vinylidene chloride)/poly(lactic acid)/multi‐walled carbon nanotube composites via constructing filler‐wrapped porous structure

AbstractHerein, immiscible poly(vinylidene fluoride)/poly(lactic acid) (PVDF/PLA) blends filled with multi‐walled carbon nanotubes (MWCNT) were fabricated by a facile solution flocculation method. A co‐continuous structure was formed at the blend ratio of 50v/50v. By extracting PLA, MWCNTs were found wrapped on the surface of porous PVDF. The electrical percolation threshold of porous composites is 0.25 wt.%, which is much lower than compact composites (2 wt.%). By comparing the electromagnetic interference shielding effectiveness (EMI SE) between compact and porous composites, the EMI SE of compact composites containing 15 wt.% MWCNT is ca. 30 dB, whereas 60 dB for the porous composites at the same filler loading. The enhanced shielding performance is derived from the porous structure and densely packed MWCNT on the PVDF surface that facilitates the multiple reflections of electromagnetic waves. This work provides a new thought in fabricating high performance EMI material by effectively tuning filler distribution in polymer blends.

Synergistically toughened silicone rubber nanocomposites using carbon nanotubes and molybdenum disulfide for stretchable strain sensors

Stretchable rubber nanocomposites have been investigated for detection in piezoresistive strain sensors. Tensile toughness must be improved while maintaining stretchability to realize high-performance, robust, stretchable nanocomposites. We investigate a stretchable and synergistically toughened silicone nanocomposite-based, piezoresistive strain sensor using multiwalled carbon nanotubes (MWCNTs) and molybdenum disulfide (MoS2). One-dimensional MWCNTs mechanically reinforce the silicone rubber matrix, improving tensile strength by 95% but decreasing fracture strain by 27% at 5 phr, providing an electrical percolation network. Adding two-dimensional nanolayers of MoS2 as a single filler increases fracture strain from 205% (unfilled) to 320% (5 phr MoS2), possibly due to cure retardation in the silicone rubber, preventing over-curing. Silicone nanocomposites exhibit improved tensile toughness at 8.46 kJ/m3 for 5-phr MWCNT-MoS2 hybrids due to the synergistic effects of the hybrid filler, a 125% improvement over unfilled rubber. Nanocomposites maintain a low elastic modulus (<0.45 MPa) suitable for stretchable sensors. The nanocomposite utility is demonstrated as body-attachable, piezoresistive strain sensing with a gauge factor of ∼25.95 (100%<Δε<155%), stretchability of up to 155%, and durability of over 5000 cycles. Toughened nanocomposites with MWCNT and MoS2 hybrid fillers could be useful for applications requiring robust stretchability and sensitivity.

Carbon nanotube network formation and configuration/morphology on reinforcing and conductive performance of polymer-based nanocomposites

The present research work shows that carbon nanotube network formation and configuration/morphology play significant role in mechanical and conductive performance of polymer-based nanocomposites. Using several experimental techniques and theoretical approaches, the main entities of the established networks with aligned and random morphology were identified, the underlying mechanisms of network formation and the nature of its building blocks were revealed, and the corresponding network effects on the mechanical and electrical performances of such nanocomposites using single-walled carbon nanotubes in low- and high-density polyethylene matrices were thoroughly studied. Results show that the formed network is in majority constructed from nanotube bundles, considered as stiff rod-like Brownian particles, geometrically entangled at the critical volume fraction φcv (geometrical percolation threshold). The geometrical percolation threshold was found to be independent of the network morphology (aligned of injection molded samples and random of compression molded samples). Moreover, the mechanical and rheological properties were found to be independent of the nanocomposite morphology. However, the electrical performance of such materials was surprisingly different, strongly dependent on the morphology (aligned versus random as defined above). The random configuration significantly decreases the transition of the nanocomposites from isolator to conductor. The electrical percolation threshold, φcve, was found to be by one order of magnitude lower than the corresponding geometrical threshold, thus profoundly improving the conductivity of such nanocomposites. This key discovery enables the production of not only highly reinforced and conductive nanocomposites, but also the ones with remarkable conductivity and flexibility with minimal addition carbon nanotubes.

Impact of electrical percolation on mechanical, thermal and flame properties of carbon filler‐epoxy composites

AbstractHybrid combination of carbon fillers is utilized in an epoxy matrix to enhance DC/AC conductivity and dielectric constant. Influence at electrical percolation on mechanical strength, thermal stability, co‐efficient of thermal expansion (CTE), and flame properties have been investigated since proper balance of the properties is critical. Multiwalled carbon nanotube and graphene nanoplatelets of different weight proportions are incorporated in epoxy matrix to understand their impact of electrical, mechanical and thermal properties. It is observed that weight fraction of the carbon fillers at electrical percolation tends to deteriorate the mechanical and flame properties, minimally influences thermal stability while decreasing the CTE. The weight fractions below the electrical percolation are observed to enhance mechanical and flame properties as compared to percolation level. Though the formation of network of carbon fillers is responsible for enhancement of electrical conduction and CTE, the synergy of carbon fillers is not evident in mechanical and flame properties due to dominating influence of aspect ratio, orientation, and alignment. DC conductivity of 3 × 10−6 S/m, AC conductivity of 4 × 10−2 S/m at 8 MHz is observed at electrical percolation. However, composite reveals 5% to 10% reduction in mechanical strength, while the thermal stability and glass transition (126°C) are minimally affected at percolation. Co‐efficient of thermal expansion improves to 2 × 10−6/°C and heat deflection temperature increases to 140°C. Flame properties reveal divergent trends. The need for proper balance of electrical, thermal and mechanical properties at electrical percolation is emphasized.

Piezoresistive behavior of DLP 3D printed CNT/polymer nanocomposites under monotonic and cyclic loading

This study examines the piezoresistive behavior of MWCNT/polymer composites fabricated by the digital light processing (DLP) technique. A photocurable nanocomposite resin feedstock possessing low viscosity with excellent printability and high conductivity was developed for DLP 3D printing of bulk and cellular geometries. By optimizing the resin composition and synthesis route, electrical percolation was achieved at an ultra-low MWCNT loading of 0.01 phr (parts per hundred resin), providing a conductivity of 3.5 × 10−5 S m−1, which is significantly higher than the values reported in the extant works for similar nanocomposites. Reducing the MWCNT content also enhanced the piezoresistivity of the nanocomposite due to longer inter-MWCNT distances in the percolating conductive network. Under quasi-static tensile loading, the nanocomposite with 0.01 phr MWCNT loading showed gauge factors of 2.40 and 4.78, corresponding to the elastic and inelastic regime, respectively. Quasi-static cyclic tensile tests with constant strain amplitudes (within elastic regime) revealed that the response of the nanocomposite was affected by viscoelastic deformation, which caused significant changes in the material’s strain sensing performance between consecutive load cycles. Finally, the developed resin was used to realize a self-sensing gyroid lattice structure, and its strain and damage sensing capabilities were demonstrated.

Effect of specific surface area on the rheological properties of graphene nanoplatelet/poly(ethylene oxide) composites

The rheological properties of poly(ethylene oxide) containing graphene nanoplatelets (GNPs) having different specific surface areas (SSAs) are studied using steady shear and small amplitude oscillatory shear experiments. A series of GNPs having SSAs ranging from 175 ± 5 to 430 ± 13 m2/g was prepared using a thermomechanical exfoliation process. The complex viscosity, moduli, and yield stress of the composites increase with SSA, whereas electrical and rheological percolation threshold concentrations decrease, suggesting that higher SSAs promote filler network formation. Modeling of small amplitude oscillatory shear data using a two-phase model confirms that hydrodynamic effects dominate at low concentrations below 8 wt. %, where the particles are noninteracting. At higher concentrations, the response is dominated by filler-phase contributions. We demonstrate that the two-phase model parameters can be used to track the exfoliation of graphite into GNPs. Fitting of rheological percolation curves using Utracki and Lyngaae–Jørgensen models at low concentrations (noninteracting regime) resulted in aspect ratios between 19 and 76. At high concentrations (interacting particles), the aspect ratios determined by the Krieger–Daugherty model ranged between 5 and 24 due to aggregation. The highest aspect ratios (defined as the ratio of major dimension to minor dimension) were associated with GNPs that had the highest SSA of 430 m2/g. Strain sweeps revealed that the critical strain for the onset of nonlinear viscoelasticity scaled with SSA above the percolation threshold. The scaling relationships of the critical strain and storage modulus with volume fraction were used to infer the fractal dimensions of filler networks.

Corrosion, electrical and thermal behaviour of graphene modified polyester powder coatings

This work investigates polyester powder coatings containing graphene on aluminium alloy AA6060. The coatings were developed with a multifunctional approach in order to combine efficient barrier properties and high electrical and thermal conductivity. Graphene contents up to 10 wt% were introduced in the composite powder coatings. The barrier properties were investigated by means of electrochemical impedance spectroscopy (EIS) in 0.1 M NaCl solution. This technique was also employed to obtain information about the electrical parameters of the coatings. Although barrier properties remain high over immersion times up to 35 days, a strong increase of coating capacitance and a decrease of coating resistance were observed by EIS for the coatings with graphene content above 1 wt%. Impedance data were interpreted on the base of the electrical percolation theory in order to correlate the increase of capacitance and the decrease of the resistance to the existence of graphene-rich agglomerates in the composites coatings. Moreover, the thermal behaviour of the composite powder coatings was preliminarily evaluated indicating that the introduction of graphene can improve heat dissipation.

PET/Graphene Nanocomposite Fibers Obtained by Dry-Jet Wet-Spinning for Conductive Textiles.

The combination of polyethylene terephthalate (PET), one of the most used polymers in the textile industry, with graphene, one of the most outstanding conductive materials in recent years, represents a promising strategy for the preparation of conductive textiles. This study focuses on the preparation of mechanically stable and conductive polymer textiles and describes the preparation of PET/graphene fibers by the dry-jet wet-spinning method from nanocomposite solutions in trifluoroacetic acid. Nanoindentation results show that the addition of a small amount of graphene (2 wt.%) to the glassy PET fibers produces a significant modulus and hardness enhancement (≈10%) that can be partly attributed to the intrinsic mechanical properties of graphene but also to the promotion of crystallinity. Higher graphene loadings up to 5 wt.% are found to produce additional mechanical improvements up to ≈20% that can be merely attributed to the superior properties of the filler. Moreover, the nanocomposite fibers display an electrical conductivity percolation threshold over 2 wt.% approaching ≈0.2 S/cm for the largest graphene loading. Finally, bending tests on the nanocomposite fibers show that the good electrical conductivity can be preserved under cyclic mechanical loading.

CNT ink as an electrode additive for an effective hybrid conductive network in silicon microparticle/graphite anodes

Conductive additives are receiving much attention as they can play an important role in the challenging intrinsic properties of Si anode in lithium-ion batteries. Hence, these carbonaceous materials not only facilitate electrical percolating pathways but also secure structural integrity within the electrode. However, the intrinsic properties of conventional conductive materials such as point-to-point contact of carbon spheres and severe entanglement of CNT make it difficult to achieve an efficient conductive network in the electrode. Here, we use well-dispersed CNT ink as an additive for a homogeneous conductive network in silicon microparticle/graphite (SiMP/Gra) electrodes. By using the CNT ink with Super P particles, a unique hybrid conductive network, composed of 0D and 1D carbon materials, was formed in the SiMP/Gra electrode. To find an optimized conductive structure, a series of electrodes with different weight ratios between CNT and Super P was prepared and electrochemically tested. Through the investigation, the 1 wt% of CNT ink addition makes the best electrochemical performance. The superior performance of SiMP/Gra CNT ink 1.0 wt% electrode can be explained by the optimized hybrid conductive network with Super P cluster bridges between CNT strands. Furthermore, the optimal CNT-Super P hybrid network effectively grasps SiMP/Gra particles and connects electrode components, resulting in improved electrical conductivity and structural integrity upon repeated cycles. The described CNT ink additive concept and the hybrid conductive network could be useful suggestions in electrode design, considering conductive structure and electrochemical performance.

Influence of carbon nanofiller geometry on EMI shielding and electrical percolation behaviors of polymer composites

The effects of carbon nanofiller geometry on the electrical percolation behavior, electromagnetic interference (EMI) attenuation, and EMI attenuation mechanisms of polymer composites were investigated. Polylactic acid (PLA) filled with carbon nanotubes (CNT), graphene nanoplatelets (GNP), or a hybrid mixture of CNT:GNP were prepared by melt mixing to formulate composites of random nanofiller dispersion and distribution states. The CNT-based composite showed higher EMI attenuation performance and electrical conductivity than the GNP-based and CNT:GNP-based composites. In addition, the CNT-based composite showed a higher ability to attenuate the EMI by absorption than the GNP-based and CNT:GNP-based composites. It is speculated that fiber-like geometry and the smaller surface area of CNT compared to GNP have reduced the reflection of the radiation at the composite external surface and facilitated the dissipation of radiation by absorption due to the effective 3D network within the PLA matrix.

Enhancement of 3D Printability by FDM and Electrical Conductivity of PLA/MWCNT Filaments Using Lignin as Bio-Dispersant.

To increase the applications of FDM (fusion deposition modeling) 3D printing in electronics, it is necessary to develop new filaments with good electrical properties and suitable processability. In this work, polymer composites filament-shaped with superior electrical performance based on polylactic acid (PLA) carbon nanotubes and lignin blends have been studied by combining solution mixing and melt blending. The results showed that composites achieve electrical percolation from 5 wt.% of nanotubes, with high electrical conductivity. Moreover, the introduction of a plasticizing additive, lignin, improved the printability of the material while increasing its electrical conductivity (from (1.5 ± 0.9)·10-7 S·cm-1 to (1.4 ± 0.9)·10-1 S cm-1 with 5 wt.% carbon nanotubes and 1 wt.% lignin) maintaining the mechanical properties of composite without additive. To validate lignin performance, its effect on PLA/MWCNT was compare with polyethylene glycol. PEG is a well-known commercial additive, and its use as dispersant and plasticizer in PLA/MWCNT composites has been proven in bibliography. PLA/MWCNT composites display easier processability by 3D printing and more adhesion between the printed layers with lignin than with PEG. In addition, the polyethylene glycol produces a plasticizing effect in the PLA matrix reducing the composite stiffness. Finally, an interactive electronic prototype was 3D printed to assess the printability of the new conducting filaments with 5 wt.% of MWCNT.

Multi-functional medical grade Polyamide12/Carbon black nanocomposites in material extrusion 3D printing

Carbon black (CB) modified polyamide 12 (PA12) nanocomposites (PA12/CB) were fabricated through melt mixing extrusion for a range of different filler weight-to-weight ratios (0.1%, 0.5%, 1.0%, 2.5%, 5.0%, and 10.0%). Filaments fabricated via thermomechanical extrusion, were employed to manufacture electrothermally conductive nanocomposites, through 3D Printing Fused Filament Fabrication (FFF). Mechanical performance was assessed, whilst, the electrical percolation threshold was identified, with the nanocomposites exhibiting electrical conductivity for a filler ratio of 2.5 wt% and above. Scanning Electron Microscopy (SEM) was conducted to reveal nanocomposite’s fracture mechanisms. Dynamic Mechanical Analysis (DMA) tests revealed a stiffening mechanism, while the antibacterial response of the nanocomposites for two bacteria was also investigated through a screening process, i.e., Escherichia coli (E. Coli) and Staphylococcus aureus (S. aureus). The highest reinforcement was observed at the PA12/CB 5.0 wt% nanocomposite material. The increase of the nanofiller concentration increased the electrical conductivity and the antibacterial performance of the nanocomposites. A better biocidal response was found against the S. aureus bacterium than the E. Coli bacterium. The studied nanocomposites, exhibited multifunctional behavior, suitable for various applications requiring enhanced mechanical performance, such as free-of-shape and stretchable conductors, circuitry resistors, Joule-heating elements, piezoresistive sensors, etc., as well as medical supplies.

Ionic Liquids as Alternative Curing Agents for Conductive Epoxy/CNT Nanocomposites with Improved Adhesive Properties

Good dispersion of carbon nanotubes (CNTs) together with effective curing were obtained in epoxy/CNT nanocomposites (NCs) using three different ionic liquids (ILs). Compared to conventional amine-cured epoxy systems, lower electrical percolation thresholds were obtained in some of the IL-based epoxy systems. For example, the percolation threshold of the trihexyltetradecylphosphonium dicyanamide (IL-P-DCA)-based system was 0.001 wt.%. The addition of CNTs was not found to have any significant effect on the thermal or low-strain mechanical properties of the nanocomposites, but it did improve their adhesive properties considerably compared to the unfilled systems. This study demonstrates that ILs can be used to successfully replace traditional amine-based curing agents for the production of electrically conductive epoxy/CNT NCs and adhesives, as a similar or better balance of properties was achieved. This represents a step towards greater sustainability given that the vapor pressure of ILs is low, and the amount needed to effectively cure epoxy resins is significantly lower than any of their counterparts.

Hybrid assembly of polymeric nanofiber network for robust and electronically conductive hydrogels

Electroconductive hydrogels have been applied in implantable bioelectronics, tissue engineering platforms, soft actuators, and other emerging technologies. However, achieving high conductivity and mechanical robustness remains challenging. Here we report an approach to fabricating electroconductive hydrogels based on the hybrid assembly of polymeric nanofiber networks. In these hydrogels, conducting polymers self-organize into highly connected three dimensional nanostructures with an ultralow threshold (~1 wt%) for electrical percolation, assisted by templating effects from aramid nanofibers, to achieve high electronic conductivity and structural robustness without sacrificing porosity or water content. We show that a hydrogel composed of polypyrrole, aramid nanofibers and polyvinyl alcohol achieves conductivity of ~80 S cm−1, mechanical strength of ~9.4 MPa and stretchability of ~36%. We show that patterned conductive nanofiber hydrogels can be used as electrodes and interconnects with favorable electrochemical impedance and charge injection capacity for electrophysiological applications. In addition, we demonstrate that cardiomyocytes cultured on soft and conductive nanofiber hydrogel substrates exhibit spontaneous and synchronous beating, suggesting opportunities for the development of advanced implantable devices and tissue engineering technologies.

Recyclable and super-stretchable conductive elastomeric composites with a carbon nanostructure interconnected network structure for effective thermal management and excellent electromagnetic wave suppressor

ABSTRACT The increasing demand for flexible electronics and portable gadgets has resulted in an increase in the amount of emitted EM radiation in recent years. Conductive carbon black (VCB XC 72) is a quasi-graphitic structure of clustered carbon particles that was deemed an ideal material for the development of extremely flexible electromagnetic interference (EMI) shielding materials. The sequential solution and melt mixing process has been used to generate a flexible and recyclable zinc oxide cross-linked, and VCB XC 72 nanofiller reinforced EMI shielding material. The ionic cross-linked network, created by other self-clustering ion duplets of Zn2+ ions, gave rise to the amazing recycling and reprocessing abilities of carboxylated acrylonitrile butadiene rubber (XNBR). The cross-linked XNBR and conductive black combination formed a tunable inferential framework that provided absorption, reflection, and multiple reflection shielding mechanisms. Based on the findings of the morphological study, it has been determined that the scattered and distributed carbon black clusters included inside XNBR rubber are creating the pathway for electrical hopping. As a result, the electrical percolation threshold has been lowered, and EMI shielding has significantly improved. The rubber composites had improved thermal characteristics in addition to having outstanding mechanical performances. Hopefully, these findings will pave the way forward for the development of smart electronic devices and environmentally friendly EMI shielding materials.

Spark plasma sintered graphene/copper calcium titanate ceramic composites with negative permittivity and enhanced thermal conductivity

Ceramic composites with negative permittivity have provoked considerable interests of researchers in electronic and dielectric devices due to the extraordinary electromagnetic performance in radio-frequency (RF) region. Herein, graphene/CaCu3Ti4O12 (GR/CCTO) ceramic composites were spark plasma sintered, of which the dielectric and thermal properties were demonstrated at RF region. An electrical percolation was identified with GR content varying from 10 wt% to 14 wt% which presenting as a dramatic increase of ac conductivity. The conduction mechanism changed from hopping conductivity to metal-like conductivity. Meanwhile, the real permittivity (ε′) turned from positive to negative which indicating an intrinsic transition of dielectric response mechanism. Therefore, Drude model was applied to elucidate the RF negative permittivity (ε' < 0) which manifesting the low-frequency plasmonic state of delocalized electrons in composites. The constructed GR networks in composites also leaded to the enhanced thermal conductivity due to the dominating contribution of phonon vibration in GR sheets. Besides, theoretical models of capacitive and inductive equivalent circuits were used on impedance spectra which successfully clarified the inductive character of negative permittivity. This work benefits expounding the generation and regulation mechanism of negative permittivity and will be favorable to exploring brand-new applications of ceramic composites.

Local electrical conductivity of carbon black/PDMS nanocomposites subjected to large deformations

The full-field microscale electrical behavior of polydimethylsiloxane (PDMS) matrix composites with 12 wt% (below the electrical percolation threshold) and 20 wt% (above the electrical percolation threshold) carbon black (CB) nanoparticles was obtained with the aid of Conductive Atomic Force Microscopy (C-AFM) as a function of uniaxial tensile strain. A comparison between the macroscale and the microscale 2D strain fields showed that 25 × 25 μm2 specimen domains can serve as a representative surface element (RSE) to describe the macroscale mechanical response under finite deformations. The same surface domain size was shown to serve as RSE for the local electrical behavior of CB/PDMS nanocomposites at small and large strains. The transverse specimen contraction due to the Poisson’s effect increased the through-thickness conductivity of 12 wt% CB specimens, with a rapid increase in the total electric current measured at the scale of the RSE taking place above 23% uniaxial true strain. The locally dominant tunneling conductance in the undeformed specimen state transitioned to a combination of Ohmic (linear local current-voltage (I–V) characteristics) and tunneling (parabolic local I–V characteristics) at 35% uniaxial true strain. In comparison, the local I–V characteristics of undeformed PDMS composites with 20 wt% CB were a combination of Ohmic (contributing the majority of the total current) and tunneling. Upon application of 35% uniaxial true strain the vast majority of local conduction sites became Ohmic, while the total electric current at the scale of the RSE increased relatively linearly with applied strain.

Chemiresistive Polymer Percolation Network Gas Sensor Created with a Nanosphere Template

AbstractThe sensitivity and limits of detection (LOD) of chemiresistive gas sensors can often be improved by increasing the surface area of the sensing material that interacts with the analyte. This process is referred to as nanostructuring. Nanostructured polypyrrole (PPy) chemiresistive sensors for ammonia detection were created with the aid of a nanosphere template. Polystyrene nanospheres are deposited to form a template between interdigitated electrodes, and chronoamperometry is then used to grow PPy between the electrodes within the gaps of the nanospheres. The PPy growth is controlled to create electrical percolation networks. After removal of the nanospheres by dissolving them, the percolation behavior and sensing response of the nanostructured PPy sensors are investigated. The nanostructured percolation sensors show higher sensitivity and lower LOD to ammonia than percolation networks prepared without nanosphere templates. An optimal nanostructured ammonia percolation sensor with a chemiresistive sensitivity of 2.59 ± 0.20% ppm−1 and a LOD of 71 ± 6 ppb is obtained.