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ToF-SIMS quantitative analysis has been tested using copolymers with well-defined structures and polymer blends with controllable interaction. It has been shown that quantitative analysis is possible using the most characteristic ions. Secondary ions with similar molecular structures behave very similarly in terms of quantitative analysis. However, the results have also indicated the presence of matrix effects for certain secondary ions. In particular, H-bonding which is a common interaction phenomenon in polymers has been identified as a source of matrix effects. H-bonding mainly affects fragments that directly accept protons and from the point of view of quantitative analysis those fragments are not suitable.

Blends of 50 wt% of poly(vinyl chloride) (PVC) and 40 wt% of styrene butadiene rubber (SBR) with 10 wt% of acrylonitrile butadiene rubber (NBR) as the compatibilizer were prepared in a Haake mixer. An inversion of phase continuity was observed when the sulfur concentration was changed from 0.0 to 2.0 parts per hundred parts of resins (phr) in the blends containing an NBR with an acrylonitrile content of 29.5 wt% (NBR-29). The SBR phase, which is continuous in the unvulcanized blend, changes progressively into the dispersed phase as sulfur concentration increases. This is explained by the viscosity increase of the rubber caused by crosslinking. There is no phase inversion as a result of increasing sulfur concentration when the compatibilizer NBR-29 was replaced by an NBR with an acrylonitrile content of 40 wt% (NBR-40). The SBR phase is discrete in the unvulcanized blend with NBR-40 as the compatibilizer. A change in phase continuity occurs during processing of the vulcanized PVC/NBR-29/SBR (50/10/40) blends. A torque peak in the torque curve during processing is correlated to the transition of the PVC phase continuity. There is a gradual increase in the torque curve after the torque peak. The rubber particle size decreases as a result of such a post-peak increase in the torque. The torque peak and the post-peak increase in the torque are absent in the case of the binary blends (PVC/NBR and PVC/SBR). The post-peak increase in the torque is attributed to the interfacial reaction between SBR and NBR that resides in the PVC phase. A novel method developed recently was applied to study the interface development during processing. An interface with a higher rubber concentration develops during processing of the compatibilized blends.

The blends of poly(hydroxyether of bisphenol A) (phenoxy) and poly(vinyl acetate) (PVAc) were prepared through in situ polymerization, i.e., the melt polymerization of diglycidy ether of bisphenol A (DGEBA) and bisphenol A in the presence of PVAc. The polymerization reaction started from the initial homogeneous ternary mixture of PVAc/DGEBA/bisphenol A; the phase separation induced by reaction occurred as the polymerization proceeded. The phenoxy/PVAc blends with PVAc content up to 20 wt % were obtained and were further characterized by the solubility, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electronic microscopy (SEM). The results indicate that no intercomponent reaction occurred during the in situ polymerization. All the blends display separate glass transition temperatures (Tg's) the very fine phase-separated morphology was obtained by this polymerization blending method. Mechanical tests show that the prepared blends exhibited substantial improvement of mechanical properties, especially in impact strength, which could be ascribed to the formation of the fine phase-separation morphology during in situ polymerization. The thermogravity analysis (TGA) of the blends showed that the thermal stability of the PVAc-rich phases in the blends was enhanced in comparison to the pure PVAc due to the synergistic contribution of the two phases in energy transportation.

The electrical conductivity, current-voltage characteristics and morphology of carbon black-filled immiscible blends of poly(vinylidene fluoride)(PVDF) and high density polyethylene (HDPE) were investigated. Carbon black (CB) had stronger affinity to HDPE than to PVDF, resulting in its selective localization in the HDPE phase. The CB content and PVDF/HDPE volume ratio were the two main factors influencing the electrical conductivity, current-voltage characteristics, and morphology. At a fixed PVDF/HDPE volume ratio of 1/1, a percolation threshold of 0.037 volume fraction of CB was observed, and that value was much lower than that for conventional CB-filled polymer composites. At a fixed CB content (10 wt% CB), a maximum electrical conductivity was observed at a PVDF/HDPE volume ratio of 2.75. An increase in CB content in the composites with a fixed PVDF/HDPE volume ratio (1/1) and an increase in PVDF content in composites with a fixed CB content (10 wt%) greatly decreased the domain size of the PVDF phase. A positive-temperature-coefficient effect was used to determine the location of CB in the blends.

In this study, a series of poly( l -lactic acid) (PLLA)/poly(ethylene oxide) (PEO) blends with different PLLA concentrations was prepared. Films of these blends crystallized with and without a coverslip were characterized by the presence and absence of banded structures, respectively. This difference in morphology was observed because the PEO component of the blends was oxidized at a high temperature (125 °C) in air without the protection of a coverslip. X-ray photoelectron spectroscopy (XPS) results showed that the surface of the blends crystallized in nitrogen without a coverslip contained mostly PLLA while the surfaces of the same blends crystallized under a coverslip contained only a moderately higher concentration of PLLA than their bulks. The migration of PLLA to the surface of the blends during crystallization in nitrogen when no coverslip was used was due to its low surface tension. Phase images obtained using atomic force microscopy (AFM) indicated that the banded structures consisted of valleys and ridges, which were in fact flat-on and edge-on lamellae, respectively. A detailed time-of-flight secondary ion mass spectrometry (ToF-SIMS) examination suggested that PLLA and PEO were located mainly on the surfaces of the ridges and valleys, respectively.

Blends of phenolphthalein poly(ether ether sulfone) (PES-C) with a thermotropic liquid crystalline copolyester (LCP) were prepared. Miscibility, morphology, thermal behavior, and mechanical properties of the PES-C/LCP blends with various compositions were studied by using differential scanning calorimetry (DSC), wide-angle x-ray diffraction (WAXD), dynamic mechanical analysis (DMA), tensile tests, and scanning electron microscopy (SEM). Both DSC and DMA studies showed that the blends have two glass transition temperatures (T g) corresponding to those of the PES-C-and LCP-rich phases, respectively. PES-C and LCP are partially miscible, the T g's varying with composition. Young's modulus increases slightly with increasing LCP content owing to the high modulus of LCP, whereas the tensile strength greatly decreases with increase of LCP content. The interfaces between PES-C and LCP are weakly bonded, with rather poor interaction. SEM observations revealed that the blends have a two-phase structure and...

Hydrogen bonding between poly(vinyl phenol) (PVPh) and poly(4-vinyl pyridine) (PVPy) was studied by time-of-flight secondary ion mass spectrometry (ToF-SIMS), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. Systematic studies were performed on various blends of PVPh and PVPy in different solvents, including ethanol and N,N-dimethylformamide (DMF). Both X-ray photoelectron spectroscopy and contact angle results showed no surface segregation of any component for the blends and complexes of PVPy and a low molecular weight PVPh. Excess of PVPh was found at the surface of the blends when a high molecular weight PVPh was used. However, after annealing at 90°C in a vacuum oven for five days, the surface and bulk compositions are the same. These findings reveal that the surface of blends of high molecular weight polymers may not be in the thermodynamic equilibrium state. The peak intensity of the characteristic pyridyl ions of the blends, especially the PVPh/PVPy complexes, such as the peak at m/z=106, was greatly enhanced by the hydrogen bonding. The quantitative relationship between the ion intensity and the surface composition was studied. A linear relationship was established between the intensity ratio of some of the characteristic ions and the surface concentration determined by XPS.

A method for determining the degree of relaxation of a clean metal surface from realistic LEED data is presented, using the complex Fourier transform of the beam intensity as a function of electron momentum (the Patterson function).

Exposure of a clean Ir(111) surface at room temperature to approximately 20 L of oxygen produces a sharp (2×2) LEED pattern. This LEED pattern can be caused by two fundamentally different adsorbate superstructures: a p (2×2) array of oxygen atoms (one‐quarter monolayer coverage) or three independent, equivalent domains of a (1×2) superstructure rotated 120° with respect to one another (half‐monolayer coverage). Dynamical calculations have been performed for the three most symmetric adsites on this surface: the on‐top site and the two different types of threefold sites for both the p (2×2) and the three domains of (1×2) superstructures. The results show that the oxygen adatoms, either forming a p (2×2) superstructure or the three domains of (1×2) superstructure rotated 120° with respect to one another, reside on the threefold site directly above a vacancy in the second substrate layer with an interlayer spacing of 1.30 A corresponding to an Ir–O bond length of 2.04 A.