High-density Polyethylene Substrate Research Articles

Cold spray deposition of high density polyethylene composite powders

In this paper, we investigate the use of the cold spray additive manufacturing technique to deposit micron-sized composite particles of high-density polyethylene (HDPE) compounded with either micron or nanometer sized particles of silicon dioxide (SiO2) or copper (Cu). In this study, the mass fraction of the SiO2 and copper particles added into the final composite powders was varied between 0.5 % and 9.1 % and the deposition efficiency of each composite powder was measured. Deposition of the composite powders onto an HDPE substrate was successful even at the highest particle loadings tested. In each case, an optimal mass fraction of silicon dioxide or copper particles was observed with a maximum value of deposition efficiency larger than that of the pure HDPE. For the silicon dioxide composite powders, the deposition efficiency nearly doubled compared to the pure HDPE powders. The improvement of deposition efficiency at moderate particle loadings is likely due to the increase in the impact kinetic energy of the particles resulting from the increase in the density of the composite powders. While the decrease in deposition efficiency at high particle loadings is likely the result of the increased coverage of the silicon dioxide and copper particles on the surface of the HDPE powders limiting the interaction between the HDPE of the composite powder with the HDPE substrate. SEM images show that it is possible to create a smooth, dense, and uniform thin-film polymer composite coating using cold spray.

Novel antibacterial nanoscale glass surfaces coated with vanadium pentoxide/phosphorus pentoxide (V2O5-P2O5) thin film by the thermionic vacuum arc plasma

In the present study, vanadium pentoxide/phosphorus pentoxide (VP, 50%V2O5 + 50% P2O5) glasses is synthesized by traditional melt-quenching method, and Thermionic Vacuum Arc (TVA) is used to deposit the VP-bulk glass on high-density polyethylene (HDPE) and glass substrates. Morphological, X-ray diffraction (XRD) and Raman analysis showed VP thin films are homogeneous, uniform and nanosized structures on both substrates, and it has a glass structures. Deposition of the VP thin films significantly (p<0.05) increases the hydrophilicity of HDPE substrates decreasing the water contact angle from 80.57°±4.09° to 33.11°±1.37° Escherichia coli O157:H7 ATCC 35150, Listeria innocua ATCC 33090, and Staphylococcus aureus ATCC 6538P are totally inhibited by both VP-coated substrates after 2-h of contact time. Modified Kirby-Bauer tests prove the antibacterial activity of VP-coated HDPE substrates was higher than VP-coated glass substrates against all bacteria. The highest zone of inhibition (43.33±1.77 mm) is observed against Staph. aureus on VP-coated HDE substrates. The study proves the nanoscale structure of the deposited VP thin films is effective in demonstrating antibacterial activity.

Dopamine-Based Copolymer Bottlebrushes for Functional Adhesives: Synthesis, Characterization, and Applications in Surface Engineering of Antifouling Polyethylene.

Nonpolar materials like polyolefins are notoriously challenging substrates for surface modification. However, this challenge is not observed in nature. Barnacle shells and mussels, for example, utilize catechol-based chemistry to fasten themselves onto all kinds of materials, such as boat hulls or plastic waste. Here, a design is proposed, synthesized, and demonstrated for a class of catechol-containing copolymers (terpolymers) for surface functionalization of polyolefins. Dopamine methacrylamide (DOMA), a catechol-containing monomer, is incorporated into a polymer chain together with methyl methacrylate (MMA) and 2-(2-bromoisobutyryloxy)ethyl methacrylate (BIEM). DOMA serves as adhesion points, BIEM provides functional sites for subsequent "grafting from" reactions, and MMA provides the possibility for concentration and conformation adjustment. First, the adhesive capabilities of DOMA are demonstrated by varying its content in the copolymer. Then, terpolymers are spin-coated on model Si substrates. Subsequently, the atom transfer initiator (ATRP) initiating group is used to graft a poly(methyl methacrylate) (PMMA) layer from the copolymers, with 40% DOMA content providing a coherent PMMA film. To demonstrate functionalization on a polyolefin substrate, the copolymer is spin-coated on high-density polyethylene (HDPE) substrates. A POEGMA layer is grafted from the ATRP initiator sites on the terpolymer chain on the HDPE films to provide antifouling characteristics. Static contact angle values and Fourier transform infrared (FTIR) spectra confirm the presence of POEGMA on the HDPE substrate. Finally, the anticipated antifouling functionality of grafted POEGMA is demonstrated by observing the inhibition of nonspecific adsorption of the fluorescein-modified bovine serum albumin (BSA) protein. The poly(oligoethylene glycol methacrylate) POEGMA layers grafted on 30% DOMA-containing copolymers on HDPE show optimal antifouling performance exhibiting a 95% reduction of BSA fluorescence compared to nonfunctionalized and surface-fouled polyethylene. These results demonstrate the successful utilization of catechol-based materials for functionalizing polyolefin surfaces.

Rechargeable pore-filled composite hollow fiber membranes for water vapor separation

We propose a new method of using high-density polyethylene (HDPE) ultrafiltration hollow fibers, which are inexpensive but difficult to use as a dehumidification membrane. Dehumidification membranes have a wide range of applications and can also offer the benefit of water recovery. Conventional membranes for gas separation consist of a substrate and a thin layer that selectively permeates a desired gas. However, low-cost substrates such as HDPE are limited in their application due to the presence of large pores that prevent defect-free thin layer formation. To address the issue of large pores, we utilized hydrogels made from viscous solutions, that can be stably positioned in large pores. Specifically, we filled the pores of the HDPE substrate with hydrogels consisting of glycerin, polyvinyl alcohol (PVA), and glutaraldehyde (GA). The pore-filled membranes capable of separating water vapor were 40GPGM and 50GPGM, which were filled with 40GPM (40 wt% glycerin/1 wt% PVA/0.5 wt% GA) and 50GPG (50 wt% glycerin/1 wt% PVA/0.5 wt% GA), respectively. Since the pore-filled membranes were filled with viscous hydrogels, they could be washed and recharged. Accordingly, they showed good rechargeability when measuring properties during multiple pore-filling and washing processes. The water vapor permeance/selectivity/water flux of the pore-filled membranes were measured at various temperatures and feed flow rates. The water vapor permeance/selectivity/water flux of 40GPGM and 50GPGM measured at 35 °C and 3.5 L/min were 3400 GPU/110/0.12 kg/m2∙hr and 2398 GPU/469/0.14 kg/m2∙hr, respectively. After continuous operation for 30 days, it was confirmed that the pore-filled membranes had good long-term stability.

Antibacterial efficiency of cadmium thin films deposited by the thermionic vacuum arc

In this study, thin films of the pure Cadmium (Cd) were deposited on glass and high-density polyethylene (HDPE) samples by the Thermionic Vacuum Arc (TVA) method. The structural and surface morphological properties of Cd thin-films were investigated using X-ray diffraction patterns (XRD), field emission scanning electron microscope (FE-SEM), and atomic force electron microscope (AFM). The water contact angle (WCA) was determined by a Krüss DSA100 model goniometer. The antibacterial activities of the Cd-coated and uncoated samples were investigated by direct-contact test and modified Kirby-Bauer test against Escherichia coli O157:H7 ATCC35150, Staphylococcus aureus ATCC6538P and Listeria innocua ATCC33090. Cd thin films deposited on both samples were found to be in crystalline form. The Crystallite size of the films deposited on glass and HDPE were calculated as 52.1 and 72.5 nm, respectively. The SEM and AFM depict the Cd films uniform distribution of grains. The root mean square (Rms) surface roughness of Cd thin film was found as 39.3 nm and 70.3 nm on glass and HDPE substrates, respectively. The WCA measurements showed the cadmium coatings increased the hydrophobicity of glass and HDPE samples. Direct-contact test showed both Cd-coated samples totally inhibited E. coli O157:H7 and L. innocua strains after 2-h of contact time. Modified Kirby-Bauer test indicated the Cd-coated HDPE samples showed the highest antibacterial activity against L. innocua however Cd films did not have any antibacterial activity for both samples against S. aureus.

Tuning the detection limit in hybrid organic-inorganic materials for improving electrical performance of sensing devices

Research in hybrid electronics has included advances in materials, devices and architectures. However, in practice, controversy still exists on some details which limit hybrid materials to high-performance applications, such as processing–structure–design–property relations. This paper describes a practical approach to enhancing the sensing performance of a prototype ammonia gas sensor based on electrical conductivity changes, percolation theory and current limitation to a semiconducting polymer-metal oxide medium. This device is based on fully-gravure printed polyaniline/indium - tin oxide nanocomposites, Pani100−xITOx [0 ≤ x≤ 100% (wt/wt)], layers on a freestanding high-density polyethylene substrate. We find that the electrical current of the device decreases and tends to saturate as the gas concentration increases, and the value of this electrical current limit (IL) depends on x: the higher the value of x, the smaller the IL, when the current that flows through the electronic device was dominated by the ITO-nanoparticle filled PAni, which increase the concentration of hopping carriers and contribute to the desired electrical response of a heterogeneous gas sensor. In this regime, we find a good linear relationship between x and ammonia concentration. These findings suggest new directions for future research on the development and investigation of organic-inorganic devices in which the electrical current variation is desired for enhanced sensitivity and stability of hybrid sensors.

Improving the adhesion of polyethylene surfaces using Side-Chain crystalline block copolymer

While polyethylene is widely used in consumer products, its use in other applications is limited because of low adhesive properties. In this study, the adhesive properties of high-density polyethylene were improved by a facile chemical treatment which was no require the special equipment or reagents. This simple treatment enabled the homogeneous modification of a polyethylene surface by dipping in a dilute solution containing a side-chain crystalline block copolymer (SCCBC) for a short time. SCCBC comprises of a block copolymer with one monomer containing long alkane side chains that form the side-chain crystalline units and the other that contains functional monomers. The adhesive strength of the high-density polyethylene film modified by SCCBC, as determined using a T-peel test and tensile shear test, was stronger than the non-modified high-density polyethylene substrate. Furthermore, this facile method imparted these strong adhesive properties to high-density polyethylene over a wide variety of treatment conditions such as temperature of SCCBC solution, concentration, dipping time and types of solvent.

EFFECT OF ADDING BORON CARBIDE (B4C) TO POLYMER FOR PRODUCING SURFACE COMPOSITE BY FRICTION STIR PROCESSING

Friction stir processing (FSP) is a new solid state technique, it is employed for theimprovement of the mechanical properties of a material and the production of surface layercomposites instead of conventional processing technologies. This research aims to study theability of applying Friction Stir Processing (FSP) to modify the surface of high densitypolyethylene (HDPE) reinforcing by B4C with a particle size of 0.4?m, Groove in themiddle of HDPE surface made to fill by B4C. Varity in the groove depth (0.6, 1.2 and1.8)mm used according to B4C ratio on HDPE substrate particles. Friction stir process wascarried out, using tool with cylindrical shape of pin and shoe tool to produce surface layercomposite. The effect of processing parameters including rotational and transverse speeds onthe mechanical properties of composite layer was studied. Wear test results show apronounced improvement in wear resistance of HDPE surface through reinforcementadditions of B4C at a ratio (5%, 10% and 15% ), where wear rate improved by (60%, 71%and 63%) respectively, as compared with as received HDPE, the surface compositeHDPE/B4C have good wear resistance. Hardness test results indicate that the hardness ofcomposite layer reinforced with (5%,10% and 15%) particles improved by( 26%, 35% and28% )respectively as compared with received HDPE. OM revealed that high tool rotationalspeed resulted in homogeneous distribution of B4C particles and vice versa.

Experimental and theoretical investigation of sensing parameters in carbon nanotube-based DNA sensor.

Nowadays, sensitive biosensors with high selectivity, lower costs and short response time are required for detection of DNA. The most preferred materials in DNA sensor designing are nanomaterials such as carbon and Au nanoparticles, because of their very high surface area and biocompatibility which lead to performance and sensitivity improvements in DNA sensors. Carbon nanomaterials such as carbon nanotubes (CNTs) can be considered as a suitable DNA sensor platform due to their high surface-to-volume ratio, favourable electronic properties and fast electron transfer rate. Therefore, in this study, the CNTs which are synthesised by pulsed AC arc discharge method on a high-density polyethylene substrate are used as conducting channels in a chemiresistor for the electrochemical detection of double stranded DNA. Moreover, the response of the proposed sensor is investigated experimentally and analytically in different temperatures, which confirm good agreement between the presented model and experimental data.

Numerical Simulations of the High-Velocity Impact of a Single Polymer Particle During Cold-Spray Deposition

In this paper, deposition of polymer powders was studied numerically for the cold-spray deposition technique. In cold spray, a solid particle is impacted on a substrate at high velocity. The deformation and heating upon impact have been shown to be enough to result in particle deposition and adhesion even without melting the particle. Here, a systematic analysis of a single high-density polyethylene particle impacting a semi-infinite high-density polyethylene substrate was carried out for initial velocities ranging between 150 and 250 m/s using the finite element analysis software ABAQUS Explicit. A series of numerical simulations were performed to study the effect of a number of key parameters on the particle impact dynamics. These key parameters include particle impact velocity, particle temperature, particle diameter, composition of the polyethylene particle, surface composition and the thickness of a polyethylene film on a hard metal substrate. The effect of these parameter variations on the particle impact dynamics were quantified by tracking the particle temperature, deformation, plastic strain and rebound kinetic energy. The trends observed through variation of these parameters provided physical insight into the experimentally observed window of deposition where cold-sprayed particles are mostly likely to adhere to a substrate.

Microstructure of Activated Carbon Particles Coated on High Density Polyethylene (HDPE) for Wastewater Treatment Application

This research aims to study the effect of activated carbon particles in adsorption of the methylene blue as a replacement of wastewater treatment when coated on a high density polyethylene (HDPE) substrate (e.g. flat sheet and cosmo ball substrates). Prior to coating, the activated carbon has been cleaned using tab water to remove ashes which blocks the activated carbon pores. Coating was done by applying epoxy material using brushing technique, and then sprayed the activated carbon on epoxy either manually or using spray machine. The thickness and morphological of the coatings were characterized using Scanning Electron Microscopy (SEM). Analyses conducted have confirmed that granuler activated carbon coating layers ranged between 100 to 500 μm have been successfully deposited on different shapes of HDPE substrates. The coatings deposited on HDPE substrate produced high surface roughness of around 7 μm. The ability of the coated samples in removing the colour of methylene blue is believed due to the high porosity of the activated carbon(AC). The surface area has been increased dramatically if compared with uncoated substrate since the BET of activated carbon is 426 m2/g .

Effect of Substrate Interferences from High‐Density Polyethylene on Association of Simulated Ignitable Liquid Residues with the Corresponding Liquid

The effect of substrate interferences from high-density polyethylene (HDPE) on the ability to associate an ignitable liquid residue with the corresponding liquid standard, using statistical procedures, is demonstrated. Gasoline, kerosene, and lighter fluid, at three different evaporation levels, were spiked onto HDPE and subsequently burned to generate simulated ignitable liquid residues (ILRs). Samples were extracted using a passive headspace procedure and analyzed by gas chromatography-mass spectrometry. The total ion chromatograms were subjected to data pretreatment procedures prior to principal components analysis and Pearson product moment correlation. Using the combination of these statistical procedures, simulated ILRs were successfully associated with the corresponding liquid type, despite the presence of compounds inherent to the HDPE substrate, as well as those resulting from pyrolysis of the substrate.

Immobilized MWCNT support osteogenic cell culture

The broad use of versatile, strong, lightweight multi-walled carbon nanotubes (MWCNT) for use in biomaterial applications is tempered by ongoing debate about their safety. Recent reports suggest that factors such as their diameter and surface coating affect their function and cytotoxicity. The cell culture surfaces used in the current study were made of MWCNT immobilized in a high-density polyethylene substrate, differentiating it from most studies of MWCNT cytotoxicity. The purity, chemical functionalization, and immobilization of MWCNT were evaluated to elucidate their effect on MWCNT behavior relative to controls. While purity was found not to be significant in determining the behavior of cells on MWCNT relative to standard controls, the presence of carboxyl functional groups was generally associated with reduced cell metabolic activity, proliferation, and differentiation as measured using the MTS assay, nucleic acid incorporation, and alkaline phosphatase expression, respectively. This study demonstrates that the culture of osteogenic cells on surfaces made of nonfunctionalized and immobilized MWCNT is associated with a level of cell growth and differentiation comparable to those of standard tissue culture controls.

Improved interfacial adhesion of membrane electrode assemblies using polymer binders and pore-filling membranes in alkaline membrane fuel cells

The development of alkaline membrane fuel cells (AMFCs) will enable the use of non-platinum catalysts and hydrocarbon-based electrolyte membranes. Such catalysts are intrinsically stable and have activities similar to that of platinum in an alkaline environment. A pore-filling membrane has been made from a porous, high-density polyethylene substrate to fabricate durable, AMFC membrane electrode assemblies (MEAs). Because of the low binding ability of the hydrocarbon ionomer in the preparation of AMFC MEAs, polymer binders were added to the catalyst slurries to form a firmly bound interface. A content of 20 wt% polyethylene (PE) binder, the same material as the porous substrate in the pore-filling membrane, exhibits the best attachment of the non-platinum catalyst particles to the pore-filling, hydrocarbon anion-exchange membranes. The addition of a PE binder improves adhesion at the MEA interface and diminished contact resistance. The improved durability of the MEA is confirmed by continuous, constant-voltage operation. Adhesion between the cathode catalyst layer and the pore-filling membrane is also investigated after mild hot-pressing to test the use of decal method in the fabrication of AMFCs. The catalyst layer with the PE binder was completely transferred to the pore-filling membrane at 50 °C and 30 bar cm−2, but not for the PTFE binder.

Micropunching Lithography for Generating Micro- and Submicron-patterns on Polymer Substrates

Conducting polymers have attracted great attention since the discovery of high conductivity in doped polyacetylene in 1977(1). They offer the advantages of low weight, easy tailoring of properties and a wide spectrum of applications(2,3). Due to sensitivity of conducting polymers to environmental conditions (e.g., air, oxygen, moisture, high temperature and chemical solutions), lithographic techniques present significant technical challenges when working with these materials(4). For example, current photolithographic methods, such as ultra-violet (UV), are unsuitable for patterning the conducting polymers due to the involvement of wet and/or dry etching processes in these methods. In addition, current micro/nanosystems mainly have a planar form(5,6). One layer of structures is built on the top surfaces of another layer of fabricated features. Multiple layers of these structures are stacked together to form numerous devices on a common substrate. The sidewall surfaces of the microstructures have not been used in constructing devices. On the other hand, sidewall patterns could be used, for example, to build 3-D circuits, modify fluidic channels and direct horizontal growth of nanowires and nanotubes. A macropunching method has been applied in the manufacturing industry to create macropatterns in a sheet metal for over a hundred years. Motivated by this approach, we have developed a micropunching lithography method (MPL) to overcome the obstacles of patterning conducting polymers and generating sidewall patterns. Like the macropunching method, the MPL also includes two operations (Fig. 1): (i) cutting; and (ii) drawing. The "cutting" operation was applied to pattern three conducting polymers(4), polypyrrole (PPy), Poly(3,4-ethylenedioxythiophen)-poly(4-styrenesulphonate) (PEDOT) and polyaniline (PANI). It was also employed to create Al microstructures(7). The fabricated microstructures of conducting polymers have been used as humidity(8), chemical(8), and glucose sensors(9). Combined microstructures of Al and conducting polymers have been employed to fabricate capacitors and various heterojunctions(9,10,11). The "cutting" operation was also applied to generate submicron-patterns, such as 100- and 500-nm-wide PPy lines as well as 100-nm-wide Au wires. The "drawing" operation was employed for two applications: (i) produce Au sidewall patterns on high density polyethylene (HDPE) channels which could be used for building 3D microsystems(12,13,14), and (ii) fabricate polydimethylsiloxane (PDMS) micropillars on HDPE substrates to increase the contact angle of the channel(15).

Development of a portable isotropic neutron spectrometer

A portable neutron spectrometry and dosimetry measurement device is in the process of development, which will be capable of accurate characterisation of neutron fields. The instrument is an amalgamation of two well-known techniques the Bonner-sphere and the surface barrier detector.Recent developments in semiconductor materials have allowed the growth of large-area thin-film based semiconductors upon high density polyethylene substrates, on which this detector is formed. Herein we discuss three plausible detection devices and test their results.

Epitaxial crystallization of olefin block copolymers (OBCs) on uniaxially oriented isotactic polypropylene and high-density polyethylene films

The epitaxial crystallization behavior of olefin block copolymers (OBCs) on uniaxially oriented isotactic polypropylene (iPP) and high-density polyethylene (HDPE) films has been investigated by transmission electron microscopy (TEM). The crystallizable blocks of the OBCs under investigation were epitaxially nucleated by both iPP and HDPE substrates and epitaxial growth of OBC lamellae was observed. Epitaxial crystallization of the OBCs has been found for slow and fast cooling conditions from the melt which pointed to the strong interaction between the polyolefin substrates and the OBCs. However, the epitaxial morphology of the OBCs strongly depends on their octene concentration difference (Δ C8) between crystallizable and non-crystallizable blocks, which probably is related to the OBC segregation strength in the melt. With high Δ C8 the development of epitaxial crystallization of the OBC was restricted within isolated crystalline domains surrounded by the amorphous phase. In contrast, with low Δ C8 the oriented lamellae of the OBC were distributed homogeneously on iPP but formed separated crystalline domains on HDPE, which has a stronger nucleation capability than iPP on the crystalline OBC blocks because of its similar molecular architecture. Our study points to epitaxy as another reason for the strong interaction between OBC and polyolefins which causes the advanced compatibilization behavior of OBCs when compared with conventional random copolymers.

Photocatalytic degradation of methylene blue in water solution by multilayer TiO 2 coating on HDPE

A multilayer photocatalytic TiO 2 coating on a high-density polyethylene (HDPE) disk was found to degrade aqueous methylene blue in a batch reactor study. The TiO 2 coating was fabricated by a low-temperature method using polyurethane resin (PU) as a barrier layer for HDPE and as a binding agent for two TiO 2 layers. Adequate adhesion between the HDPE substrate and PU barrier in aqueous environment was ensured with an oxygen plasma treatment. The photocatalytic effect of immersed TiO 2 coating on the degradation of methylene blue in aqueous solution was monitored by UV–vis spectrometry as a function of UV-illumination time. Samples were allowed to adsorb methylene blue in the dark for 1 h before the UV-degradation experiments were started. The percentages of methylene blue degraded during 6 h UV illumination ( λ = 365 nm) varied from 80% to 92%. The degradation followed pseudo-first order reaction kinetics, and the observed rate constants ( k obs) were between 0.27 and 0.43 h −1.

Construction issues surrounding a portable four-band neutron detection system

Solid state-based surface barrier detectors (SBDs) have been employed in neutron radiation dosimetry for over half a century, each combination of detector featuring positives and pitfalls. Here the implications of constructing a portable neutron spectrometer device, based upon moderating high-density polyethylene substrates and utilising different types of large-area solid state SBDs, are discussed.

3D porous polymeric conductive material prepared using LbL deposition

In this work a 3D porous polymeric conducting material is derived from a multi-percolated polymer blend system. The work has focused on the preparation of low surface area porous substrates from polymer blends followed by the deposition of polyaniline conductive polymer (PANI) on the internal porous surface using a layer-by-layer (LbL) technique. The approach reported here allows for the percolation threshold concentration of polyaniline conductive polymer (PANI) to be reduced to values of no more than 0.19%. Furthermore, depending on the amount of PANI deposited, the conductivity of the porous substrate can be controlled from 10 −15 S cm −1 to 10 −3 S cm −1. Ternary and quaternary multi-percolated systems comprised of high-density polyethylene (HDPE), polystyrene (PS), poly(methyl methacrylate) (PMMA) and poly(vinylidene fluoride) (PVDF) are prepared by melt mixing and subsequently annealed in order to obtain large interconnected phases. Selective extraction of PS, PMMA and PVDF result in a fully interconnected porous HDPE substrate of ultra-low surface area and highly uniform sized channels. This provides an ideal substrate for subsequent polyaniline (PANI) addition. Using a layer-by-layer (LbL) approach, alternating poly(styrene sulfonate) (PSS)/PANI layers are deposited on the internal surface of the 3-dimensional porous polymer substrate. The PANI and sodium poly(styrene sulfonate) (PSS) both adopt an inter-diffused network conformation on the surface. The sequential deposition of PSS and PANI has been studied in detail and the mass deposition profile demonstrates oscillatory behavior following a zigzag-type pattern. The presence of salt in the deposition solution results in a more uniform deposition and more thickly deposited PSS/PANI layers. The conductivity of these samples was measured and the conductivity can be controlled from 10 −15 S cm −1 to 10 −5 S cm −1 depending on the number of deposited layers. In the case of a porous sample which can be crushed, applying a load to the substrate can be used as an additional control parameter. In that sample a high load results in higher conductivity with values as high as 10 −3 S cm −1 obtained. The work described above has focused on very low surface area porous substrates in order to generate a conductive device with the lowest possible concentration values of polyaniline, but high surface area substrates can also be readily prepared using this approach.