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Porous methylsilsesquioxane ͑MSQ, CH 3 SiO 1.5 ) films were created by making polymer blends with trimethoxysilyl norbornene ͑TMSNB͒ and triethoxysilyl norbornene ͑TESNB͒, where the polymer served as a sacrificial place-holder. Upon exposure to elevated temperatures, the polymers decomposed within the MSQ matrix to form nanosize voids in the films. Different pore microstructures were observed by transmission electron microscopy and atomic force microscopy, depending on the functional groups on the polymeric sacrificial material used. The differences in microstructure have been correlated to variations in the chemical reactivity between the sacrificial polymer and the MSQ matrix. Solid-state 29 Si and 13 C nuclear magnetic resonance, and Fourier transform infrared spectroscopy have been used to study the chemical structure of the TMSNB and TESNB:MSQ mixtures. Indications of a chemical bond between the TMSNB and the MSQ have been found in these mixtures; however, the same results were not observed for the TESNB system. The addition of an acid catalyst to the TESNB was found to induce a reaction between the TESNB sacrificial polymer and the MSQ. The percent weight loss of the MSQ and its mixtures ͑with TMSNB and TESNB͒ were used to evaluate the polymer residue. F161 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.210.126.199 Downloaded on 2015-05-23 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.210.126.199 Downloaded on 2015-05-23 to IP Figure 15. Chemical structure showing the chemical bond between the TM-SNB polymer and the MSQ matrix as determined from 29 Si NMR.Journal of The Electrochemical Society, 149 ͑12͒ F161-F170 ͑2002͒ F169 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.210.126.199 Downloaded on 2015-05-23 to IP

A commercially available spin-on glass ͑methylsilsesquioxane, MSQ͒ was modified by the introduction of porosity. The porosity reduced the effective dielectric constant of the MSQ by the incorporation of air. The pores were created by adding a sacrificial polymer ͑substituted norbornene polymer͒ to the silsesquioxane matrix. The sacrificial material was thermally decomposed to form nanosize voids within the films. The physical and electrical properties of the porous films were studied as a function of the reactivity of the sacrificial polymer with the glass, and the loading and molecular weight of the sacrificial polymer. Transmission electron microscopy was used to evaluate the porous microstructure. Cross-sectional images show pores of nearly spherical geometry with 5-20 nm diam. The dielectric constant and the index of refraction of the porous MSQ were lower after the decomposition of the sacrificial material. The dielectric constant decreased from 2.7 for a nonporous MSQ film to ϳ2.2 for a film with 30 wt % loading of the sacrificial polymer. In a similar way, the index of refraction was reduced from 1.42 to 1.29 for the porous MSQ film. The mechanical properties were evaluated using nanoindentation techniques. This paper focuses on the significant improvements observed upon introduction of porosity to the films. The fracture toughness, or the resistance to crack propagation, increased dramatically with porosity, as compared with the nonporous MSQ films. As a result, thicker MSQ films can be fabricated without spontaneous cracking. The elastic modulus and the hardness of the porous films were measured and showed a reduction in both properties with increasing porosity in the film.

In this study, the mechanical and chemical properties of a series of sulfonated poly(styrene-isobutylene-styrene) (SIBS) block copolymers were evaluated using a combination of nanoindentation, dynamic mechanical analysis (DMA), elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), water absorption, and small angle X-ray scattering studies (SAXS). The materials properties were characterized as a function of the sulfonation percent in the block copolymers, as well as a result of the counterion substitution with Mg 21 , Ca 21 , and Ba 21 . Nanoindentation studies revealed that the elastic modulus (E) and hardness (H) increase with sulfonation up to a certain level, at which point, the effect of water content further hinders any mechanical reinforcement. The incorporation of counter-ions increases E and H, but the results are dependent upon the size of the counter-ion. DMA results showed that the polymer maintained the glass transition temperature (T g ) of the polyisobutylene (PIB) segment (260 C) regardless of the sulfonation level or counter-ion substituted. However, both the shoulder of the PIB T g (230 C), which was probably caused by a Rouse-type motion, as well as the T g of polystyrene (105 C) disappeared upon sulfonation. Counter-ion substitution increased the storage modulus of the rubbery plateau, which is indicative of a stronger and more thermally stable crosslinked complex formation. Additional unique relaxations were observed with the counter-ions, and could be attributed to the stretching/rotation of the SAO bond and the interaction of the cations with the oxygen in the sulfonic group. FTIR results also revealed a unique shifting of the asymmetric SAO band when counter-ions were added.