Nanomanufacturing, Volume 3, Issue 1 (March 2023) – 7 articles

In conventional chemical and electrochemical oxidation methods, it is very difficult to control the active centers, and the average prepared polymers are short and wide. The use of an electric field creates the most stable intermediate form of active centers, as well as permitting a longer half-life. Therefore, this increases the physical resistance and electrical conductivity of the polymer. In this paper, polycarbazole nanofibers were prepared using an electric field, reporting on its influences on the polymerization of carbazole. Therefore, its electrical conductivity and some physical properties were investigated. We observed the nanofibers’ shape, increasing electrical conductivity, thermal resistance and a higher molecular weight with the synthesized polycarbazole under an electric field compared to the polymer synthesized in the same conditions in the absence of an electric field. First, we chemically synthesized polycarbazole at different times. Additionally, to find the optimizing conditions, we changed certain parameters, such as the ratio of the obtained molar of initiator to monomer, the oxidant, initiator and solvent, separately, and compared the obtained results. Then, we repeated this reaction in the best conditions and under different electric fields in constant time, allowing us to characterize the shape, mass and conductivity. Next, the polymerization was carried out at the best electric field in different times. Finally, the best time and amount of electric field for polymerization were determined. The electrical conductivity of polycarbazoles was studied with the four-probe method. The conductivity of the films oxidized using FeCl₃ (dry) and protonated with p-toluenesulfonic acid (PTSA) at 3 h was higher than 8.9 × 10⁻⁴ S/cm under a 12 KV/m electric field. Additionally, the results showed an enhanced thermal resistance to ageing. Full article

Three-dimensional (3D) printing has gained increasing attention for its unique ability to create geometrically complex designs, which not only can be used for mass manufacturing but also has environmental and economic benefits. Additionally, as far as the food industry is concerned, this emerging technology has the potential to personalize products in terms of shape and/or nutritional requirements creating a wide range of food items with specially made shapes, colors, textures, tastes, and even nutrition using suitable raw materials/food components. In the future, 3D food printing could make complex food models with special interior design. This review gives attention to intelligent food packaging. Point-of-use machinery for manufacturing smart packaging, with a 3D printing approach, enables the use of multifunctional smart components and is self-identifying and highly sensitive, while using biocompatible non-toxic materials is cheaper than traditional manufacturing methods. This would create smart food packaging and in turn prevent customers from purchasing unsuitable food and thus reduce food waste. Future studies can make the process more compatible and efficient with a wide variety of materials that could be used to improve the 3D printing process. Full article

Different methods which could be used to produce colloidal dispersions of polyaniline (PANI) nano-objects without templates are described. While the methods are non-deterministic, different nano-objects (nanospheres, nanofibers, nanobelts, nanorice, nanotubes, nanorods, nanodisks, etc.) can be produced. Those most used are: (i) solution polymerization with steric stabilizers (SPS) to produce nanospheres, (ii) interfacial polymerization (IP) to produce nanofibers and (iii) solution polymerization in the presence of additives (SPA) to produce nanotubes. Oxidation of aniline in aqueous solution could produce nanotubes, nanofibers and other shapes by controlling mass transport/concentration of reactants, pH, and the presence of oligomers/additives. The different models proposed to explain the formation of various nano-objects are discussed. Mechanochemical polymerization (MCP) could produce nanofibers or nanospheres by controlling the aniline/oxidant ratio. PANI nanospheres of tunable sizes can also be produced by nanoprecipitation (NPT) of preformed PANI from its solutions using an antisolvent. The geometrical constraints to the small nano-objects made of high-molecular-weight rigid polymers are described. The conditions to produce nanostructures also affect the intrinsic properties of PANI (conductivity, crystallinity, and electroactivity). Selected technological applications of PANI nano-objects manufactured as colloidal dispersions without templates are discussed. Based on the reviewed work and models, future lines of work are proposed. Full article

This article fundamentally reviews progress in the design and manufacturing of three-dimensional (3D) graphene-based nanocomposites for technical applications. The 3D graphene nanostructures have been manufactured using techniques like the template method, chemical vapor deposition, sol-gel, freeze-drying, hydrothermal technique, and other approaches. The nanofoam has been reinforced in polymers to achieve superior structural, morphological, and physical characteristics of the ensuing polymer/graphene nanofoam nanocomposites. The polymer/graphene nanofoam nanocomposites have been manufactured using the approaches like direct template method, in situ technique, infiltration process, and other methods. The 3D nanofoam- and polymer-based nanostructures have shown high specific surface area, suppleness, electron transport, thermal conduction, mechanical resilience, and other physical properties. The technical applications of hierarchical graphene nanofoams have been observed in the fields of radiation shielding, solar cells, supercapacitors, fuel cells, and other applications. Full article

In order to study the relationship between the rheology of a surfactant’s concentrated dispersions and the oil and water liquid crystals from which O/W nanoemulsions (NEs) can be produced by water dilution, the phase diagram of a model SOW (surfactant–oil–water) system was constructed. The dispersion’s compositions to be characterized by rheology were chosen in the diagram’s regions that contain liquid crystal phases. For this, the dilution lines S/O = 25/75, 55/45, and 70/30 with a water content of 20 and 40 wt% (corresponding to surfactant concentrations between 15 and 55 wt%) were chosen. By adding these dispersions to a water pool, NEs were obtained, and it was shown that droplet size distribution depends on the amount of the liquid crystal phase in the initial dispersion and its rheology. The study of the oscillatory amplitude of the dispersion showed a linear viscoelastic plateau (G’ > G”) and a softening deformation region (G” > G’), indicating a viscoelastic behavior of the dispersions. The study was carried out at a constant temperature of 30 °C, and the results show that rheological characterization by itself is not enough to predict that monomodal droplet distributions are obtained. However, the presence and quantity of lamellar liquid crystal phase are important to obtain monodisperse and kinetically stable NEs. Full article

This review article highlights essential manufacturing strategies for the formation of graphene reinforced polymeric nanocomposites. For graphene reinforced thermoplastic, thermosetting and conducting matrix nanomaterials have been manufactured using solution casting, melt blending, in situ polymerization, electrospinning, 3D printing, and several other techniques. Solution processing has been well thought-out as an advantageous technique, relative to melt mixing, in terms of graphene dispersion in polymeric matrices. An in situ polymerization process has also been considered valuable to form homogeneously dispersed polymer/graphene nanocomposites having superior physical characteristics. Nevertheless, the manufacturing techniques for polymer/graphene nanocomposites have relative advantages and disadvantages to be considered for graphene-based nanocomposites. Moreover, numerous challenges need to be overcome to optimize the processing parameters for the fabrication of high-performance polymer/graphene nanocomposites. Full article