Self standing films

The polyphenylenes were brittle and did not form self-standing films when cast from solution. Therefore, they were considered poor materials. The use of these polymers was instead investigated as additives in polystyrene to improve processing and mechanical properties. A mixture of polystyrene and hyperbranched polyphenylene (5%) was studied and the results showed that the melt viscosity, especially at high temperatures and shear rates, was reduced by up to 80% as compared to pure polystyrene. Also, the thermal stability of polystyrene... 

The CHCl3/Et0H/H20 (4 1 0.07) solution of the DNA-lipid complex (0.25 g) was cast on a Teflon plate and the solvent was evaporated slowly under the saturated vapor at room temperature. The obtained self-standing film was (ca. 60 xm thick) water-insoluble, and physically stable (Fig. 6a). The DNA film can be obtained also from the hot-press method. Here, the powder of the DNA-lipid complex was hot-pressed at 120 °C for 1 min under... 

Lamellar double hydroxides are part of, or are precursors of, a more general family of compounds designated as pillared layered structures (PLS). We quote some terms used to describe them (Mitchell 1990 Van Damme 1990). Pillared Layered Structures are nanocomposite materials prepared by linking molecules or colloids to a layered host. They exhibit a remarkably broad spectrum of structural, chemical, electronic, ionic, optical and magnetic properties, and provide supermesh host structures in which chemical reactions or physical processes can proceed under gas-phase conditions, but at liquid/solid state densities. They can be shaped as powders, pellets, or supported or self-standing films, and can be dispersed in solid or liquid matrices. 

Gunji, T. Itagaki, S. Kajiwara, T. Abe, Y Hatakeyama, T. Aoki, R., Preparation and Properties of Siloxane/Epoxy Organic-Inorganic Hybrid Thin Films, Self-Standing Films, and Bulk Bodies. Polym. J. 2009,41,541-546. 

Ookubo N et al (1993) Microscope observation of a self-standing film of porous silicon. Mater Sci Eng B20 324-327... 

Jifickova M, Demel J, Kubat P, Hostomsky J, Kovanda F, Lang K. Photoactive self-standing films made of layered double hydroxides with arranged porphyrin molecules. J Phys Chem C 2011 115 21700-6. 

Using 4-cyano-4 -pentylbiphenyl (5CB) as nanatogen and polysulfone (PSU) as a polymer matrix (Schane 7.1) in different mass ratios, PDLC systems were obtained as free self-standing films. 

For the preparation of membranes based on HBPI or LPI or HBPI and silicaa solution of either HBPAA or LPAA or a suspension of silica in HBPAA solution were spread onto a glass substrate (treated with chlorotrimethylsilane). The resulting thin layer was kept at 60 °C for 12 h, 100 °C for Ih, 150 °C for 1 h, 200 °C for 2 h and 250 °C for 1 h. The thickness of the self-standing films obtained was about 50-100 pm. 

Ogawa M., Igarashi T., Kuroda K. Preparation of transparent silica-surfactant nanocomposite films with controlled microstructures. Bull. Chem. Soc. Jpn. 1997 70 2833-2837 Ogawa M., Ikeue K., Anpo M. Transparent self-standing films of titanium-containing nanoporous silica. Chem. Mater. 2001 13 2900-2904... 

In electronics, polyimides are now extensively used in the form of self-standing films for flexible circuitry, deposited films for interlayer dielectrics, passivation and buffer coatings, moulding thermoplastic powders for PCBs, and adhesive pastes or tapes. The basic polyimide chemistry has been adapted to fulfill the specific requirements of these applications. A series of books provides complete information not only on the chemistry of polyimides but also on their utilization in electronics [4,23,24]. The following figures summarize the chemical formulae of the most important categories of polyimide precursors or precyclized polymers that are commonly used in electronics. 

Thermal expansion coefficients are determined by thermomechanical analysis using a dilatation-penetration probe for adhesive pastes and an extension probe for self-standing films. The output of the thermal analyzer equipped with a dilatation probe is a curve plotting the variation of adhesive thickness as a function of the temperature. 

GE www.ge.com) patented both the synthesis of a new dianhydride with two ether-hnking units and its use to produce poly(ether-imides). The production process, chemical, mechanical, and electrical properties of Ultem 1000 (www.sabic-ip.com) have been recently reviewed. Research at Occidental Chemical (www.oxychem.com) has focused on the synthesis of 4,4 -oxybis(l,2-benzenedicarboxylic acid) dianhydride (OPDA, 103) and on the poly-imides prepared from this compound and various aromatic diamines. For the past 15 years new poly (ether-imides) have been proposed as thermoplastic materials to produce adhesives, self-standing films, and interlayer dielectrics. Chemical formulae of typical ether-linked aromatic diamines are illustrated in Fig. 12.14. 

Zhao B, Cai R, Jiang S, Sha Y, Shao Z (2012) Highly flexible self-standing film electrode composed of mesoporous mtile Ti02/C nanofibers for lithium-ion batteries. Electrochim Acta 85 636-643... 

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