Polydimethylsiloxanes surface composition

Chen, Gardella and Kumler106 have studied a series of polydimethylsiloxane-polystyrene block copolymers and examined the surface composition by ATR-FTIR and XPS. For AB-type PS-PDMS diblock copolymers (26) with siloxane block molecular weights of between 38,000 and 99,000, the surface was found to be exclusively polydimethylsiloxane down to a depth of 10 nm by XPS. ATR-FTIR, which samples... 

Zhu, R. Hoshi, T. Sasaki, D. Usui, R. Hagiwara, T. Yano, S. Sawaguchi, T., Surface Properties and Depth Analysis of Polyethylene/Polydimethylsiloxane Composite Prepared by Using Supercritical Carbon Dioxide. Polym. J. 2010, 42,562-566. 

Shindou, T. Katayama, S. Yamada, N. Kamiya, K., Effect of Composition on Surface Properties of Polydimethylsiloxane-Based Inorganic/Organic Hybrid Films. J. Sol-Gel Sci. Technol. 2004, 30, 229-237. 

Sometimes, a highly permeable third layer, e.g., polydimethylsiloxane, is used between the sublayer and toplayer and serves as an intermediate layer or gutter. When the surface of the sublayer is highly porous, it is often difficult to deposit a thin selective coating directly. Also when the toplayer is composed of a glassy polymer it is often difficult to obtain this layer defect-free. Under these circumstances the three-layer membrane or double composite membrane may be a good approach [31]. 

The reflectivity of the solution-air interface was measured for polydimethylsiloxane solutions in toluene. In such systems, the polymer is known to be attracted at the surface because of the negative increment of the surface tension (--S mN/m). Two isotopic compositions were tested, and they are characterized respectively by ya = 4.321 and yb = -0.98 (see Eq.(H)). Ideally in the experiment, the polymer molecular weight Mu,)i and the monomer volume fraction (j>i should be independent of composition. This was however not exactly achieved ... 

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