Polyimide nanocomposites applications

Figure 6.6 shows a scheme of the CIELab system. Park and Chang [20] prepared some polyimide nanocomposites films with pristine clay and analyzed the transparency and color change. This is an important aspect since colorless polyimide films have in particular been widely used in electro-optical devices and semiconductor applications. The measurements were obtained for 80 pm thick films by a spectrophotometer and the color coordinates on CIELab system were determined. 

PI nanocomposites have been prepared by various methods with different fillers. The nanocomposites might have many applications starting from barrier and thermal resistance to a compound with low coefficient of thermal expansion (CTE) [154-167]. These hybrid materials show very high thermal and flame retardation as well as barrier resistance and adhesion. Tyan et al. [158] have shown that depending on the structure of the polyimide the properties vary. Chang et al. [159] have also investigated the dependency of the properties on the clay modifiers. 

Polymeric nanocomposites are a class of relatively new materials with ample potential applications. Products with commercial applications appeared during the last decade [1], and much industrial and academic interest has been created. Reports on the manufacture of nanocomposites include those made with polyamides [2-5], polyolefins [6-9], polystyrene (PS) and PS copolymers [10, 11], ethylene vinyl alcohol [12-15], acrylics [16-18], polyesters [19, 20], polycarbonate [21, 22], liquid crystalline polymers [8, 23-25], fluoropolymers [26-28], thermoset resins [29-31], polyurethanes [32-37], ethylene-propylene oxide [38], vinyl carbazole [39, 40], polydiacethylene [41], and polyimides (Pis) [42], among others. 

Kovalev MK, Kalinina E, Androsov DA, Cho C. Synthesis of transparent and thermally stable polyimide-aramid nanocomposites -prospective materials for high-temperature electronic manufacture applications. Polymer 2013 54(l) 127-33. 

Thermoset polymers like polyimide, crosslinked sulfonated poly(ether ether ketone) and polyacrylate can be used for membrane applications. The presence of nanoparticle nucleates the nanopore formation with the assistance of an agent. The nanopore is responsible for the solvent separation and transportation. Membranes such as solvent filters, filters for bacteria and virus, and membrane for gas separation can be developed using clay-polymer nanocomposites [118-119]. 

Commercial membranes for CO2 removal are polymer based, and the materials of choice are cellulose acetate, polyimides, polyamides, polysulfone, polycarbonates, and polyeth-erimide [12]. The most tested and used material is cellulose acetate, although polyimide has also some potential in certain CO2 removal applications. The properties of polyimides and other polymers can be modified to enhance the performance of the membrane. For instance, polyimide membranes were initially used for hydrogen recovery, but they were then modified for CO2 removal [13]. Cellulose acetate membranes were initially developed for reverse osmosis [14], and now they are the most popular CO2 removal membrane. To overcome state-of-the-art membranes for CO2 separation, new polymers, copolymers, block copolymers, blends and nanocomposites (mixed matrix membranes) have been developed [15-22]. However, many of them have failed during application because of different reasons (expensive materials, weak mechanical and chemical stability, etc.). 

Polyimides are probably the most appropriate dass of polymers for the production of bicontinuous nanocomposites, in so far as they represent types of polymers that have been widely used in applications requiring stringent performance at high temperatures. The incorporation of continuous silica domains, therefore, is expected to enhance the high-temperature properties to bridge the gap between polymers and... 

This technique has found the following applications in addition to those discussed in Sections 10.1 (resin cure studies on phenol urethane compositions) [65], 12.2 (photopolymer studies [66-68]), and 13.3 (phase transitions in PE) [66], Chapter 15 (viscoelastic and rheological properties), and Section 16.4 (heat deflection temperatures) epoxy resin-amine system [67], cured acrylate-terminated unsaturated copolymers [68], PE and PP foam [69], ethylene-propylene-diene terpolymers [70], natural rubbers [71, 72], polyester-based clear coat resins [73], polyvinyl esters and unsaturated polyester resins [74], polyimide-clay nanocomposites [75], polyether sulfone-styrene-acrylonitrile, PS-polymethyl methacrylate (PMMA) blends and PS-polytetrafluoroethylene PMMA copolymers [76], cyanate ester resin-carbon fibre composites [77], polycyanate epoxy resins [78], and styrenic copolymers [79]. 

Polyimide layers are suitable matrix for incorporation of metal, salts, chromophores as nanoscale particles to obtain of nanocomposite materials. It was discussed the possibility of use polyimides in materials chemistry and nanomateiials, one of these applications is the use for making biomedical implants for neurology, ophthalmology, biosensor device and chips which are a powerful tool in clinical diagnostics. Another important trend is use in electronics and optoelectronics such as dielectric substrates and intermediate barrier layers, creating nanocomposite films with various nanosized particles such as dyes, metal, dielectric and other clusters. 

Tang Q-Y, Chan Y-C, Wong N-B, Qieungc R (2010a) Surfactant-assisted processing of polyimide/multiwall carbon nanotube nanocomposites formicroelectronics applications. Polym... 

Polyimides (PI) are widely used in microelectronics and photonics because of their outstanding electrical properties, heat resistance, and chemical stability [10-12], Pl/clay nanocomposites have been reported to reduce the coefficient of thermal expansion, amount of moisture absorption, and dielectric constant for improved performance in these application areas already mentioned [13-22], For example, Yano et al. [13] prepared a PI (pyromellitic anhydride-4,4 -oxydianiline)/clay composite film [(PMDA-ODA)/clay] by solution-mixing of polyamic acid (PAA) and a dimethylacetamide (DMA) dispersion of clay. They used dodecylamine as the clay modifier, and the film showed reduced thermal... 

The proposed chapter reviews the work done on 6FDA based fluorinated Pis with respect to its synthesis and various copolymers, polymerisation methods, poly(ether-imide), photosensitive polyimide, hyperbranched polyimide, addition polyimide, poly(amide-imide), poly(urethane-imide), poly(epoxy-imide), poly(ester-imide), poly(siloxane-imide), nanocomposites and non-linear optical polyimides. Finally, its application in electronics and use as a material for gas separation and corrosion protection are discussed. 

Chyi-Ming Leu Y-TC, Wei K-H (2003) Polyimide-side-chain tethered polyhedral oligomeric silsesquioxane nanocomposites for low-dielectric film applications. Chem Mater 15(19) 3721-3727... 

Yu Y-H, Yeh J-M, Lion S-J, Chen C-L, Liaw D-J, Lu H-Y, Preparation and properties of polyimide-clay nanocomposite materials for anticorrosion application , J. Appl. Polym. Sci., 2004 92 3573-82. 

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