Fluoroalkyl silane

Surface treatment has also been used to modify the threshold voltage as well as measured mobility in pentacene and Cgo TFTs [60]. These transistors have a heavily doped silicon/silicon oxide gate dielectric structure where alkyl, aUcylamine, and fluoroalkyl silanes are used to modify the Si02. Evaporated pentacene and Cgo form the active p- and n-type semiconductors. The experimental effect of these monolayer treatments is to alter Vj and effective mobility dramatically (see Table 3.2.3). For pentacene, the mobility decreases from -F, -CH3, untreated, -NH2, with a similar shift in Vj from 17 to -11V. The opposite trend is observed for Cgo, in which mobility is largest for the untreated material and smallest for the fluorinated SAM. In the case of Vji the alkylamine SAM shows the lowest VjOi 5.3 V. The underlying reasons for these trends are not completely understood. What is intriguing is how dramatic... 

ZnO A simple method of electrochemical deposition was adopted to prepare conductive hydrophobic ZnO thin films [504]. These ZnO films were fabricated by overpotential electrochemical deposition at room temperature, and the surface modified by a (flu-oroalkyl)silane showed superhydrophobic properties. The prepared thin films were treated with a methanol solution of hydrolyzed (heptadecafluorode-cyl)trimethoxysilane (CH30)3Si(CH2)2 (CF2)7CF3, 1.0 wt %) for 3 h and subsequently heated at 100 °C for 1 h. Wettability studies revealed that the surface of the as-prepared thin films showed a contact angle (CA) for water of 128.3 1.7°, whereas the superhydrophobic surface with a water CA of 152.0 2.0° was obtained by (fluoroalkyl) silane modification [504]. 

H. Zhou, H. Wang, H. Niu, A. Gestos, X. Wang and T. Lin. Fluoroalkyl silane modified silicone rubber/nanoparticle composite A super durable, robust superhydrophobic fabric coating. Adv. Mater, 24,2409-2412 (2012). 

However, most asymmetric 1,3-dipolar cycloaddition reactions of nitrile oxides with alkenes are carried out without Lewis acids as catalysts using either chiral alkenes or chiral auxiliary compounds (with achiral alkenes). Diverse chiral alkenes are in use, such as camphor-derived chiral N-acryloylhydrazide (195), C2-symmetric l,3-diacryloyl-2,2-dimethyl-4,5-diphenylimidazolidine, chiral 3-acryloyl-2,2-dimethyl-4-phenyloxazolidine (196, 197), sugar-based ethenyl ethers (198), acrylic esters (199, 200), C-bonded vinyl-substituted sugar (201), chirally modified vinylboronic ester derived from D-( + )-mannitol (202), (l/ )-menthyl vinyl ether (203), chiral derivatives of vinylacetic acid (204), ( )-l-ethoxy-3-fluoroalkyl-3-hydroxy-4-(4-methylphenylsulfinyl)but-1 -enes (205), enantiopure Y-oxygenated-a,P-unsaturated phenyl sulfones (206), chiral (a-oxyallyl)silanes (207), and (S )-but-3-ene-1,2-diol derivatives (208). As a chiral auxiliary, diisopropyl (i ,i )-tartrate (209, 210) has been very popular. 

Keywords Silanes fluoroalkyl-functional groups surface modification surface tension adhesion control lubrication silylating agents release agents. 

One type of R substituent that features only briefly in these reviews but which is growing in importance is the fluoroalkyl-containing group. There is renewed interest in fluorosilicone materials of all types including silanes. In line with the well-recognized low surface tension of aliphatic fluorocarbon-containing species, the prime interest is in the area of surface energy control. Examples of such silanes of all three types (n = 1, 2 and 3) have been reported and the purpose of this review is to summarize recent (last decade) developments in this topic. 

A final potential for these fluoroalkyl-functional silanes that must be mentioned is as bound antimicrobial agents. The use of alkyl quaternary ammonium silanes in this application is well known Plueddemann and Revis [25] have claimed fluoroalkyl-containing versions of these organosilicon quaternary ammonium antimicrobial compounds. 

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