This paper considers the feasibility of replacing indium tin oxide (ITO) with spin-coated, polymer-based composite films that are filled with multiwalled carbon nanotubes (MWNTs). The coating mixture consists of a solvent with low volatility, a dissolved thermoplastic polymer, and MWNTs. The high aspect ratio of MWNTs and their good electrical conductivity enable electrical percolation at very low concentrations, so that films can be prepared that conduct electricity while retaining good optical transparency. Although the MWNTs are driven to aggregate by Van der Waals interactions, the high viscosity of the polymer/solvent solution enables the preparation of metastable, homogeneous dispersions. However, exposing the mixtures to shear leads to aggregation, the magnitude of which depends on the duration of the shear. This effect could be observed directly in spin-coated films using both optical microscopy and conductivity measurements, with aggregation causing a drop in conductivity at high nanotube loading, and more complex non-monotonic behavior at concentrations approaching the percolation threshold.

Journal of Dairy Science 67 (1984) 2723-2733. doi:10.3168/jds.S0022-0302(84)81630-6Received by publisher: 1983-08-22Harvest Date: 2016-01-04 12:20:07DOI: 10.3168/jds.S0022-0302(84)81630-6Page Range: 2723-273

sample compartment containing an integrating sphere. For precise comparisons, both solution and solid-state absolute quantum yield of luminescence efficiencies (±10 %) were obtained using an integrating sphere, as previously reported [13]. The excitation wavelength was 320 nm for all polymers, except PFT-A (409 nm). Solutions were deoxygenated with highly pre-purified nitrogen prior to the fluorescence measurements and the sample compartment was flushed with nitrogen for thin film measurements. Fluorescent spectra of the thin films, spin cast from CHCl 3 on quartz, had an optical density of~0.5. Spectra were recorded 22.5 normal to the incident light. [1] The general approach involves attaching the MIP onto the surface of a transducer that senses binding events between the MIP and the target analyte and sends a quantifiable signal to the user. This usually requires an MIP that has been prepared in a film format, and it is often necessary to control the thickness and porosity of the film in order to optimize the sensitivity of the device. Until now, the in situ synthesis of films, via the polymerization of vinyl-based monomers (i.e., how the vast majority of MIPs are prepared), has relied on awkward adaptations of bulk-polymerization techniques, resulting in poor control of film thickness and porosity, [2] or on the use of somewhat cumbersome surface-initiated polymerization methods. [3] Due to the physical properties of traditional imprinting mixtures (e.g., high volatility and, for some cases, excessively low viscosity), spin-coating and many other standard coating techniques have not been applied at all. [2] This communication addresses this problem by introducing a simple, quick, and robust technique for preparing MIP films. Spin-coating was used to spread a MIP pre-polymerization mixture onto a substrate, and UV photolysis was used to cure the films. A novel porogenic system, which consists of a low-volatility solvent and soluble, linear polymers, is a critical feature of this process. Both the porosity and the capacity of the imprinted films were greatly enhanced in the presence of the polymer porogen. Using a chiral template, we demonstrate that the selectivity of the MIP films produced by this method is compar-COMMUNICATIONS Received

The response of thin glassy films of polystyrene and poly(vinyl acetate) to a raster-scanned, sliding SFM tip was investigated. Several of the previously proposed mechanisms of the familiar scan-induced patterns are discussed. Increases in film volume and frictional response are quantified, and suggest that the observed tip-induced plastic deformation may relate to a second-order phase transition (glass-to-rubber) beneath the sliding tip. Analysis of the scan-induced patterns suggests a crazing mechanism for the observed plastic deformation. The susceptibility of the film to plastic deformation was examined as a function of scan geometry, applied load, and the gain of the feedback loop that maintains a constant applied load. An empirical quantity called the roughening susceptibility is defined and shown to be linear with respect to variations in the scan conditions. The roughening susceptibility is highly robust in quantifying the dependences on scan history and load. This finding will be further exploited in the second paper of the series, analyzing rate and temperature dependences and their relationship to the glass transition.

Multiple regression analysis was used to obtain prediction equations to measure individual and combination effects of CaCl2 and cysteine on gel texture parameters (hardness, cohesiveness, and springiness) and on compressible water of dialyzed whey protein concentrate (WPC) systems. Predicted maximum gel hardness occurred at 11.1 mM CaCl2 or 9.7 mM cysteine. Cysteine levels at 30 mM or above drastically reduced gel hardness. Cohesiveness tended to decrease with addition of either reagent.Reagent addition generally decreased gel springiness while compressible water increased. Response surface contour predictions suggested that increases in CaCl2 or cysteine in reagent combination systems decreased hardness and increased compressible water. Predicted cohesiveness and springiness maxima were at 13.9 mM cysteine and 18.4 mM CaCl2 and at 10.3 mM cysteine and 10.0 mM CaCl2, respectively. Significant 3• 2 interaction terms in the mathematical model for combined reagent effects were observed on hardness, cohesiveness, and compressible water in the WPC gel systems.

No abstract

Citrus oil components (from cold-pressed and terpeneless oils), which contribute substantially to flavor of orange juice, were shown to be absorbed into various polymeric materials [low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), and surlyn (S)] used in aseptic packaging. Equilibration of absorption took place within 4 days, while extraction of the oil constituents occurred in 24 hr when higher temperatures were used. Substantial absorption of oil constituents by LDPE and S occurred while highly crystalline polymers (PP and HDPE) did not absorb much. The degree of absorption also depended on the nature of the oil constituents. Absorption was higher for terpene constituents followed by sesquiterpenes and aldehydes. Swelling factors showed that highly crystalline polymers (HDPE and PP) swelled less than crystalline polymeric materials. Citrus oil affected the crystallinity of the polymers by lowering their melting point and percent crystallinity.

The response of a thin-film polystyrene melt to a raster-scanned scanning force microscope tip was investigated. At high temperatures the scanning process induced intricate pattern formation whose quantitative characteristics were compared at different temperatures and scan rates. The dependence of the patterns on temperature and scan rate was consistent with time−temperature superposition as described by the Williams−Landel−Ferry (WLF) equation. WLF analysis implies an increased glass transition temperature derived from elevated pressure beneath the tip. The latter provides an estimate of the radius of the affected film region near the tip.