We have measured the diffusion of deuterated polystyrene of molecular weight 90 3 10 3 in various matrices of hydrogenated polystyrene as a function of distance from an attractive interface, oxide-covered silicon. Surprisingly long-range effects are observed. Diffusion rates an order of magnitude slower than bulk persist up to 10R g (radius of gyration) from the interface of either the diffusant or matrix polymers. The slowdown is independent of matrix molecular weight over a broad range. However, mixing of polymers within the matrix strongly influences the rates of diffusion.[S0031-9007(97)

The nanophase separated hard segment domains in solvent cast films of a segmented polyurethane and a segmented polyamide elastomer were imaged in real space using phase and topographical information from tapping-mode AFM techniques. A styrene triblock copolymer was used as a control to demonstrate the contrast mechanisms. For the segmented polyurethane and polyamide elastomers, contrast results from local stiffness variations of hard domains beneath a ca. 1 nm thick soft segment overlayer. Domain sizes and dispersity, shape, orientation, spacing, and uniformity in space are uniquely extracted from these real space AFM data. The ca. 7 nm diameter domains were relatively symmetric and uniformly space filling in the polyurethane. They were lamellar or sheetlike in the segmented polyamide elastomer, with a high aspect ratio and no curvature. There was no obvious correlation of lamellae orientation with macrocrystal aggregate (spherulite) position in the polyamide copolymer, while no such aggregates exist in the polyurethane.

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The structural development of a segmented poly(urethane-urea) (PUU) elastomer containing a low concentration of hard segment during deformation was studied by simultaneous mechanical and optical measurements (rheooptical techniques). Specifically, in-situ wide-angle X-ray diffraction and smallangle X-ray scattering using synchrotron radiation and time-resolved Fourier transform infrared spectroscopy were applied to investigate the segmental orientation of PUU chains during cyclic elongation and recovery. Formation of two different domain microstructures is characterized with changes in strain. These microstructures consist of lamellar hard domains and highly stressed nanofibrils consisting of alternating hard and crystalline soft domains. By comparing the X-ray scattering and vibrational spectroscopic data, a morphological model of hard-and soft-segment microphase separation, orientation, and strain-induced crystallization in the soft segments was obtained.

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AFM methods were applied to resolve the surface and near-surface morphology of the ionic domains in Nafion membranes, Surlyn ionomers, and other ionomers. The ionic clusters were resolved by a new tapping AFM method where low oscillation amplitudes were used, and tip−ionic domain interactions were apparently able to dominate the signal allowing nanometer-level resolution of the domains. In other operating modes, the fluoropolymer crystal or aggregate domains were imaged using tapping AFM by the normal “stiffness” contrast. By sequential images taken under different AFM conditions, the “softer” fluorine-depleted regions were found to contain ionic domains in the same topographical areas, and the changes due to swelling by water were examined in one case. A third AFM operating mode was used to examine the composition in the outermost few angstroms of the surface. Data proving the existence of a very thin fluorine-rich “barrier” layer covering the entire surface of Nafion are obtained, and its relevance to vapor versus liquid water penetration is discussed.