Poly dielectric constant polymer composites

Poly(imide)s as a class of polymer exhibit a range of properties, such as high Tg, excellent thermal stability, high chemical resistance, low dielectric constant and ease of fabrication, which have lead to important uses in the semiconductor and advance composite industries. In addition, the high aromatic content of many of these polymers and consequent high stability to ionizing radiation, leads to usage of poly(imide) films and composites in the nuclear and aerospace industries. 

Efforts at loading titanium oxide nanoparticles in PVA (commercially available from Nanophase) have been reported [65], In this report, titanium nanoparticles are dispersed in an aqueous solution of PVA with poly(melamine-co-formaldehyde). The solution is spun onto substrate and heated to generate a cross-Unked polymer-nanoparticle dielectric. A modest enhancement of dielectric constant is achieved for 600-nm thick films. Thin-film transistors using this composite show excellent pen-tacene mobility (> 0.2 cm V s ) and reasonable on/off ratios 10. Vj- —TV is reasonably high, suggesting static charge at the dielectric-semiconductor interface. 

CNT-polymer composites at very low nanotube loadings exhibit substantial electrostrictive strains when exposed to an electric field that is dramatically lower than that required by neat polymers. Zhang et al. have shown that the crystallinity. Young s modulus, dielectric constant, electrostrictive strain, and elastic energy density of electrostrictive poly(vinylidene fluoride-trifluor-oethylene-chlorofluoroethylene) P(VDF-TrFE-CFE)] can be simultaneously improved by inclusion of only 0.5 wt% of MWNTs. At an applied electric field of 54 MV m the 0.5 wt% nanocomposite generates a strain of 2%, which nearly doubles that of pure P(VDF-TrFE-CFE) polymer. 

PMMA- and poly(a-methyl-st)rrene)-PI block copolymer [9,10] blend solution containing polyurethane and PAA [11] and polyacrylamide- and PMMA-grafted PI [12]. They have achieved 10-30% decrease in a dielectric constant of polyimide films, and low-fc porous films ( fc 2.2) have been provided. Also, other methods, such as using water droplets and LiCl crystal as templates, and extracting a porogen polymer from composite PI film by supercritical CO2, have been known [47-49]. On the other hand, we have obtained ultralow-fc porous films by depositing porous PI MPs onto substrates [18,20]. 

Surface tension of a polymer solution can be controlled by judicious selection of the solvent. The very different surface tensions of poly(vinyl chloride) (PVC) solution at constant concentration in various DMF/THF mixtures are shown in Fig. 4.5a. Note, however, that on changing the solvent composition the viscosity also increases threefold at constant polymer concentration (Lee, K. H., et al. 2002). DMF is a polar solvent with a high dielectric constant (36.7 at 25°C) and high boding point (153°C), whereas THF has a low dielectric constant (7.6 at 25°C) as well as a low boiling point (65°C). 

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