High Performance Aromatic Polyimides ( Pis )

In the modern world, it is near impossible to live in an environment where one is not exposed and reliant upon the use of polymers. From credit cards to nappies; plastic bottles to prescription glasses, the applications of polymers encompass an endless range of everyday necessities. However, the significance of synthetic polymers was not universally recognised until its initial introduction as polyethylene during World War II. During the combat, they served as a critical material for insulated radar electronics (ACC, 2005).

Nano-composite plastics and carbon nanotubes have been utilized for industrial and consumer packaging, the later offering an improved packaging solution for electronics components by making the materials used lighter and stronger. Nano-porous silica is a high porous, low-density solid material that supports various temperatures making it a great insulation product that can be applied in a wide range of fields from pipe insulation to refrigerators and even microelectronics. Nanoparticle based colloids are employed in the manufacturing of sunscreens, paints, and printer inks and nano-coatings can be applied in order to obtain scratch resistant surfaces. Composite nano-materials can be considered the basis for all the other current and future commercial applications of nanotechnology.

This strength thus makes it more durable than the current polymer membranes that are in use. Its thinness results in less resistance during the process of pushing solvent molecules across the semipermeable membrane. Consequently, less pressure needs to be generated, cutting the energy costs of desalination by between 15-46% . In order for the graphene to work as a semipermeable membrane, it must contain pores, created to accommodate the exact size of a solvent particle but small enough to prevent the solute from flowing through. For desalination, the ideal size of the pores is one nanometer .

Wang, Y., Chen, K.S., Mishler, J., Cho, S.C., and Adroher, X.C. (2011)A Review of Polymer ElectrolyteMembrane Fuel Cells: Technology, Applications, and Needs on Fundamental Research, Applied Energy, 88, (4), pp. 981-1007.

Polymers have been changing the way we live for over 100 years. Their availability and diverse qualities ensure that they are always in high demand, and new polymers are always being discovered. Where does this leave the now commonplace polymers which once were ubiquitous in commerce? Polymers such as polyoxybenzylmethylenglycolanhydride (Bakelite) and polytetrafluoroethylene (PTFE) were first synthesised in 1907 and 1938 respectively, making them old by polymer standards. Although the original polymer applications are now redundant, they have found uses in new areas of society. This dynamic aspect of polymers is due to their unique structure. Polymers are created from many small molecules (or monomers) reacting with each other, and arranging

PPV, otherwise known as polyphenylene vinylene are electric conductors that processed into tiny films which emit a bright fluorescent yellow light which could potentially be a replacement for LEDS in electronics. PPV is prepared from p-xylene-bis and the addition of acetonitrile-tetrabutylammonium tetrafluoroborate and from there, the product is treated with heat to eliminate diethyl sulfide, HCL, and ethyl sulfide to form the final product, PPV. Similarly, another method, called direct chemical polymerization, formed PPV but it was only in the form of powder which could not be turned into tiny films for commercial use. In lab, we learned that PPV precursor can be synthesized in a one step reaction from p-xylene using NBs. In the reaction with

The major differences of these two chemical bonds are shown obviously in the lab. Metals has larger density values, higher hardness than polymers and able to conduct electricity while polymers is not able to. To understand the distinction in atomic bonding, one can utilize the knowledge in his

Around 150 years ago, there was no such thing as plastic or any synthetic materials that were widely used. The invention of plastic gave us the ability to produce materials that cannot be made from natural substances alone. At first the benefit of creating synthetic materials was greatly overlooked for many years, but over time the benefits became more evident. Polyethylene’s first discovery was actually made on accident. In 1899, Hans von Pechmann discovered polyethylene at the bottom of a test tube in his laboratory (Sharp 18). He was convinced that this chemical was a waste product that could be found after chemical reactions had taken place. Making this assumption, he disregarded the chemical for what seemed to be practical reasons at the

Sometimes, the greatest breakthrough originates from something simple. In the case of graphene, the breakthrough started when scientists began to slice graphite, a common substance present in pencil, atom by atom. When it reaches to an atom thick, each single layer is known as graphene. It turns from being a humble pencil lead to a revolutionary material that may earn the title ‘material of the decade’. The properties of graphene are extraordinary, it is recorded as the best electrical and thermal conductor in the world. Even though the material is known to be harder than a diamond, it successfully shocked scientists for its flexibility. These facts sparked the curiosity of scientists and encouraged them to explore more of this material.

Polyimides are high performance polymers with excellent electrical properties, high thermal stability, and high strength and stiffness at elevated temperatures. They also have a high chemical resistance and are therefore typically not soluble in common solvents. Because of solubility issues the molecular weight (MW) and molecular weight distribution (MWD) of polyimides is near impossible to obtain and in some cases the data listed is based on soluble precursors to the particular polyimide of interest. These precursors are typically only soluble in amide solvents and because of this the results obtained are questionable due to strong interactions that the polymer, mobile phase/eluent, and stationary phase/column have with one another due to the polyelectrolyte effect.

This phenomenon is a result of the separation of carbon from the metal carbide, which occurs at a high rate upon cooling, in Ni grains and occurs heterogeneously at the various grain boundaries. Thus, carbon can precipitate out of the grain boundaries, resulting in greater thickness of graphene at the edges of a layer. However, extremely high quality uniform monolayers of graphene have been deposited using polycrystalline copper foils, on diameters of up to 76 cm2,10. Raman analysis shows that copper foils treated at atmospheric pressure, show up to 95% monolayer coverage, with 5% bi-layer or tri-layer graphene10. These values are not related to the growth time or the rate of heating and cooling. In addition, copper foils are relatively cost-efficient and are etched simply with solvents that are readily available. Chemically etching the transition metal is the best method to transfer graphene deposited on the substrate, resulting in free floating graphene membranes.

Graphene is a form of carbon which has recently been receiving a great deal of attention. Some have come to call it “the wonder material” due to its many extraordinary properties. Although isolated in 2004, graphene's properties had been calculated decades earlier. It consists of a single layer of carbon atoms arranged in a hexagonal lattice. A single sheet of graphene is stronger than steel and yet remains very flexible, retaining all of its properties despite being bent and unbent multiple times. It is able to sustain extremely high electric current densities, is impermeable to all gasses, has a thermal conductivity double that of diamond and a very high electron mobility at room temperature. It is also easily chemically functionalized,

However, polymer composites with conductive fillers are influenced by the interconnectivity of the conducting fillers within the polymer matrix. A conducting polymer has many advantages like reduced weight, lower density, flexibility of control of conductivity and lower manufacturing costs [3], [4]. In recent years, polymer based carbon filled composites consisting of a sandwich of a conductive polymer between a conductor and microwave absorber have been used in wideband microwave shielding [5]. The most frequently used EM absorbers consist of materials with high dielectric losses and magnetic loss materials. These materials include carbon filament [6], carbon fiber (CF) [7], carbon nanotubes [8], [9], carbon black [10], graphite [11], graphene oxide [12], metal fiber [13] and ferrites [14].

Fig.5 shows the XRD patterns for pure PVdF-HFP, undispersed GPE and nanocomposite gel films dispersed with different amount of Al2O3 and MgAl2O4 nanofillers. The characteristic XRD peaks of PVdF-HFP, observed at Bragg angles, 2θ ~17.7˚, 20.0˚, 26.5˚, 38.4˚, 39.0˚, 45.0˚ and 65˚ indicate its semi-crystalline nature (Fig. 5a). The XRD pattern of undispersed GPE shows a broad hump between 12˚ and 28˚ (Fig. 5b) which shows the predominant amorphous nature of the GPE. The PVdF-HFP peaks at 17.7˚, 28.0˚, 26.5˚ overlap in the broad peak and the peaks at 38.4˚, 39.0˚, 45.0˚ and 65˚ disappear. These changes reveal that the liquid electrolyte dominates the crystallographic feature of PVdF-HFP in GPE and functions as a plasticizer

This paper covers advantages of organic semiconductors over the conventional one’s and also the use of organic semiconductors and polymers to make OLED’s and PLED’s.