Research

 

Synthesis of Conductive and Magnetic Nanomaterials

NPNL has expertise in the synthesis and customization of various types of conductive and magnetic nanomaterials, including carbon nanotube, graphene, graphene nanoribbon, metallic nanowires, and metallic nanoparticles. Carbon nanotubes are synthesized using the chemical vapor deposition technique, graphene and its derivatives are synthesized using the Hummers’ method, hydrothermal reduction, thermal reduction and electrochemical exfoliation techniques, graphene nanoribbons are synthesized using alloy intercalation technique from the parent carbon nanotubes, metallic nanowires and nanoparticles are synthesized by the hydrothermal and AC electrodeposition techniques. The synthesized nanofillers are multifunctional and can be used in various applications, such as electrical, dielectric, mechanical, thermal, optical, tribological, gas sensing, hydrophobic, biosensing, and wastewater treatment.

 

Undoped and nitrogen-doped carbon nanotubes appropriate for EMI shielding and charge storage, respectively. HRTEM images of (a) parent carbon nanotube and (b) graphene nanoribbon. (c) and (d) show schematics of fully and partially longitudinally opened carbon nanotube, respectively. Few-layer graphene oxide synthesized by the Hummers’ method. Silver nanowires with an average diameter and length of 25 nm and 3.2 μm, respectively, synthesized by the AC electrodeposition technique.

 

Arjmand M, Ameli A, Sundararaj U. Featured Back-Cover Photo. Journal of Macromolecular Materials and Engineering. 2016; 301(5): 640.

Arjmand M, Sadeghi S, Khajehpour M, Sundararaj U. Carbon Nanotube/Graphene Nanoribbon/Polyvinylidene Fluoride Nanocomposites: Rheological and Dielectric Properties. Journal of Physical Chemistry C, 2017; 121: 169-181.

Arjmand M, Abbasi Moud A, Li Y, Sundararaj U. Outstanding Electromagnetic Interference Shielding of Silver Nanowire: Comparison with Carbon Nanotube. RSC Advances, 2015; 5: 56590-56598.

Arjmand M, Sundararaj U. Effects of Nitrogen Doping on X-band Dielectric Properties of Carbon Nanotube/Polymer Nanocomposites. ACS Applied Materials & Interfaces, 2015; 7: 17844-17850.


 

Conductive/Magnetic Polymer Nanocomposites as Polymer-based Dielectrics, Electrostatic Discharge and Antistatic Materials and Electromagnetic Interference (EMI) Shields

Polymers have been identified as versatile candidates toward electrical applications due to their lightweight, low cost, corrosion resistance, easy processability, and improved design options. However, the electrically insulative and non-magnetic nature of polymers makes them inapplicable for applications where a specific range of electrical conductivity is required. The employed solution is to incorporate conductive and/or magnetic materials (fillers) into the polymer matrix. Polymer composites containing conductive/magnetic fillers have been shown to feature both the intrinsic physical properties of the polymers and an adjustable electrical conductivity/magnetic permeability, arising from the formation of a conductive/magnetic filler network within the polymer matrix. Changing the conductive filler content makes it possible to develop an insulative, semi-conductive or conductive composite. The polymer composites in the insulative, semi-conductive and conductive regions are suitable as dielectric materials, electrostatic discharge (ESD) and antistatic materials, and electromagnetic interference shields, respectively. It is worth noting that, due to the multifunctionality of nanofillers, the developed nanocomposites could feature other enhanced properties such as thermal, mechanical, hydrophobic and barrier.

 

Percolation curve of typical conductive filler/polymer composites Electrospun nanofiber mats of polyamide 6/polyaniline coated with nitrogen-doped carbon nanotubes Flexible mats of poly(vinylidene fluoride)/copper nanowire nanofibers Segregated hybrid poly(methyl methacrylate)/graphene/magnetite nanocomposites for electromagnetic interference shielding

 

Arjmand M. Electrical Conductivity, Electromagnetic Interference Shielding and Dielectric Properties of Multi-walled Carbon Nanotube/Polymer Composites. PhD Thesis, University of Calgary, 2014.

Santos JPF, da Silva AB, Arjmand M, Sundararaj U, Bretas RES. Nanofiber of Poly(Vinylidene Fluoride)/Copper Nanowire: Microstructural Analysis and Dielectric Behavior. European Polymer Journal, 2018; 101: 46-55.

Santos JPF, Arjmand M (co-first author), Melo GHF, Chizari K, Sundararaj U, Bretas RES. Electrical Conductivity of Electrospun Nanofiber Mats of Polyamide 6/Polyaniline Coated with Nitrogen Doped Carbon Nanotubes. Materials and Design, 2018; 141: 333-341.

Sharif F, Arjmand M (co-first author), Abbasi Moud A, Sundararaj U, Roberts E.P.L. Segregated Hybrid Graphene/Magnetite/PMMA Polymer Nanocomposites Towards Electromagnetic Interference Shielding. ACS Applied Materials and Interfaces, 2017; 9:14171-14179.

Arjmand M, Chizari K, Krause B, Pötschke P, Sundararaj U. Effect of Synthesis Catalyst on Structure of Nitrogen-doped Carbon Nanotubes and Electrical Conductivity and Electromagnetic Interference Shielding of their Polymeric Nanocomposites.  Carbon, 2016; 98: 358-372.


 

Development of Nanomaterials and Polymer Nanocomposites toward Gas (Ammonia) Sensing

Recently, there has been significant interest in the identification and detection of ammonia in a specific environment. Ammonia (NH3), a highly toxic gas, widely exists in the air, soil and water. For humans, the skin, eyes, and respiratory tract can be injured by high concentrations of NH3 (ca. >300 ppm). Ammonia is also naturally produced in the human body by various metabolic activities. In the medical sector, the presence of excessive amounts of ammonia in exhaled human breath can be treated as indications of several diseases related to dysfunctions of liver and kidneys. Hence, the detection of ammonia gas is very important in terms of both environmental, as well as health monitoring sectors. To detect ammonia, the use of traditional analytical techniques, such as mass spectrometry, is limited because of the slow response time and the large size of these instruments. Accordingly, there is a need to develop cost-effective gas sensing technologies that are reliable, portable, and highly sensitive. The application of chemiresistive materials, materials whose electrical conductivity varies upon exposure to a gas analyte, as the sensing elements in electronic noses has been widely investigated. Intrinsically conductive polymers, conductive nanofillers, and conductive filler/polymer nanocomposites (CPNs) have recently attracted the attention as chemiresistive gas sensors. 

 (Left): Preparation of nitrogen-doped reduced graphene oxide/polyaniline nanocomposites toward ammonia sensing; (Right): Synergism between polyaniline and nitrogen-doped reduced graphene oxide toward ppm sensing of ammonia. 

Tanguy N, Arjmand M, Yan N. Nitrogen-Doped Graphene Polyaniline Nanocomposites for Ultrasensitive Ammonia Gas Detection. To be submitted to Carbon.

Tanguy N, Arjmand M, Yan N. Facile Route for the Preparation of Water Dispersible Phosphorus Doped Reduced Graphene Oxide. To be submitted to Nature Communications.

Tanguy N, Arjmand M, Zarifi MH, Yan N. Wireless Ammonia Sensor based on Polyaniline/Phosphorous doped Graphene Nanocomposites Immobilized on Microstrip Resonators. To be submitted to ACS Nano.


 

Development of Polymer-based Friction Materials for Brake Pads for Automobile and Railroad Industries

According to a statistical summary released in February 2015 by the US Department of Transportation, failing of vehicle’s components accounts for about 2% of vehicle crashes, and 22% of such failures arise from brake pad problems. Therefore, choosing an appropriate composite toward the effective and safe performance of the brake friction materials is a challenging task. Friction composites, as a part of a vehicle safety system, should hold some characteristics such as high wear resistance, low weight, durability, low noise, stable friction coefficient, availability and low price. To fulfill the mentioned features, more than ten ingredients are incorporated within a friction material, categorized into four distinct classes of materials, viz., binder, fibrous ingredient, filler, and friction modifier. In NPNL, we seek to explore polymer-based friction materials to satisfy the requirement of high-tech industries such as aerospace, automobile and railroad. 

Ahmadijokani F, Shojaei A, Arjmand M (corresponding author), Alaei Y, Yan N. Effect of Short Carbon Fiber on Thermal, Mechanical and Tribological Behavior of Phenolic-based Brake Friction Materials. Composites Part B, 2018, 168: 98-105.

Ahmadijokani F, Shojaei A, Arjmand M (corresponding author), Alaei Y, Yan N. Tribological Behavior of Phenolic-based Brake Friction Materials: Effect of Carbon Fiber Reinforcement. Wear, 2018, 420: 108-115. 

Arjmand M, Shojaei A. Tribological Characteristics of Rubber-based Friction Materials. Tribology Letter 2011; 41(2): 325-336.