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A series of bis(phenoxyketimine)titanium dichloride complexes are prepared and analyzed as catalysts for living, isoselective propylene polymerization upon activation with methylaluminoxane (MAO). Mechanical testing has shown that each of these polymers have exhibited good elastomeric properties.

The effects of surface roughness on the deformations and loading and unloading forces of various polymeric surfaces were studied. The results show that depending on the nature of the roughness and also the load time some polymer surfaces may exhibit a roughness-dependent adhesion but a sharp roughness-independent repulsive regime while others a=having the same RMS roughness may exhibit an adhesion that is largely independent of the roughness.

Interfaces between donor and acceptor semiconducting polymers are critical to the performance of polymer light-emitting diodes and organic solar cells. Similarly, interfaces between a conjugated polymer and a dielectric play a critical role in organic thin-film transistors. Often, these interfaces are difficult to characterize with conventional methods. Resonant soft x-ray reflectivity (R-SoXR) is a unique and relatively simple method to investigate such interfaces. R-SoXR capabilities are exemplified by presenting or discussing results from systems spanning all three device categories. We also demonstrate that the interfacial widths between active layers can be controlled by annealing at elevated temperature, pre-annealing of the bottom layer, or casting from different solvent mixtures. The extension of R-SoXR to the fluorine K absorption edge near 698 eV is also demonstrated. [ABSTRACT FROM AUTHOR]

Partial (Auger) yield near edge x-ray absorption fine structure (NEXAFS) is a structural analytical technique that has been primarily used to measure the spatial orientation and chemical bonding of small molecules on solid (i.e., inorganic or semiconductor) surfaces. In this article we demonstrate that the building block (BB) scheme proposed by Outka and co-workers [Phys. Rev. Lett. 59, 1321 (1987)] for analyzing NEXAFS spectra can be applied to model the molecular orientation of larger molecules, provided one accounts properly for kinetic energy losses of the Auger electrons traversing through the sample and hence the attenuation in measured Auger yield. We test the applicability of the proposed "modified" BB (MBB) model by measuring the orientation of a self-assembled monolayer (SAM) of -O[sub 1.5]Si-(CH[sub 2])[sub 2]-(CF[sub 2])[sub 8]F, SF-SAM (SiO[sub x]), deposited on top of SiO[sub x]-covered silicon wafer as a function of the entrance grid bias (EGB) of the channeltron photoelectron detector. Our measurements of the EGB-dependent electron escape depth reveal that a crude depth profiling within the top ≈5 nm of the sample is possible by increasing the negative EGB on the channeltron detector, at the highest bias thus selecting only the Auger electrons, which have suffered negligible energy loss. In addition, we discuss how the order parameter method introduced recently by Stöhr and Samant [J. Electron Spectrosc. Relat. Phenom. 98-99, 189 (1989)] can be used to determine the molecular orientation of large organic molecules on surfaces. We also show that by accounting for energy losses of the NEXAFS Auger electrons (attenuation of measured Auger yield), the corrected order parameter (COP) approach gives good estimates of the orientation of molecules. We present a comparison between the MBB and COP models using experimental data collected from NEXAFS experiments from semifluorinated (SF) mesogens, -(CH[sub 2])[sub x](CF[sub 2])[sub y]F, which... [ABSTRACT FROM AUTHOR]

A norbornene monomer containing MeldrumEs acid is effectively copolymerized with polyethylene by using a nickel [alpha]-iminocarbaxamidato complex, which has provided high-melting, semicrystalline polymers with a tunable incorporation of the functional comonomer. The studies have shown the ability to tune cross-linked polyethylene properties by comonomer incorporation and have also analyzed the valuable structure/property relationships in these materials.

Novel binuclear complexes are prepared by linking two nickel centers through a bis(benzyl) fragment. Monotonic and step-cyclic stress-strain tests have shown that the materials have displayed large strains at break and excellent elastic recoveries at large strains and that materials with desirable properties are not achieved by using a mononuclear initiator has shown the advantage of growing the polymer via a telechelic mechanism.

The interfaces of conjugated polyelectrolyte (CPE)/poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) bilayers cast from differential solvents are shown to be very smooth and sharp by using resonant soft X-ray reflectivity (RSoXR). The results have shown that the nonpolar MEH-PPV layer is not much disturbed by casting the CPE layer from a polar solvent and a baseline is used for understanding the role of interfacial structure.

A system is designed consisting of a symmetric poly(styrene-b-2 vinyl pyridine) (PS-PVP) diblock copolymer matrix containing nanoparticles whose surfaces can be modified to be energetically similar to one of the blocks or amphiphilic with respect to the two blocks. By incorporating the particles into the block copolymer matrix, precise control of the location of the particles within the matrix is demonstrated by varying the composition of ligands on the particle surfaces.

A method is demonstrated to self-assemble metal nanoparticle into two-dimensional lattices. The periodic hole pattern of photoresist (PR) fabricated on GaAs substrate by holographic lithography is highlighted.

Presents information on a study which considered the swelling of a polymer glass by sorption of a small molecule penetrant in a regime characterized by so-called case-II diffusion. Methodology of the study; Results and discussion.

Presents information on a study which considered front formation and steady-state front motion in a one-dimensional polymer system undergoing case-II diffusion. Analysis of the problem with a steady-state moving front; Results of the study; Conclusions.

Presents a study which investigated the problem of adhesion at the interface between two polymers using a fracture mechanics approach. Effect of viscoelastic deformation of the bulk polymers; Micromechanical behavior of the interface on the fracture toughness of the interface; Formulation of the governing equations for a small scale yielding problem.

Presents a study that demonstrated the existence of a maximum viscoelastic energy dissipation at a characteristic interface crack velocity which depends on micromechanical properties of the interface, the viscoelastic properties of the bulk polymers and the specimen dimensions. Limitations of the small scale yielding analysis; Formulation of governing differential equations for interface crack growth; Description of the constant adhesive stress model.