AbstractPolyacrylamide and poly(acrylic acid) form a water‐insoluble phase when solutions of the two having concentrations that are not too low are mixed. The insoluble complex contains nearly stoichiometric 1 : 1 ratios of acrylamide and acrylic acid. The phase behavior of the ternary system was studied as a function of the degree of neutralization, α, of poly(acrylic acid). The complex is not formed when α is high. The formation of the complex was studied by measurement of pH increases observed when poly(acrylic acid) was titrated with polyacrylamide to infer a degree of linkage, θ, between the two polymers. A Hill plot of the data showed that the association was cooperative when the molecular weight was high.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal characterization of poly(acrylic acid)J. J. Maurer, D. J. Eustace, and C. T. RatcliffeCite this: Macromolecules 1987, 20, 1, 196–202Publication Date (Print):January 1, 1987Publication History Published online1 May 2002Published inissue 1 January 1987https://doi.org/10.1021/ma00167a035RIGHTS & PERMISSIONSArticle Views3211Altmetric-Citations142LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (869 KB) Get e-Alertsclose Get e-Alerts

Phosphorus‐31 nuclear magnetic resonance spectroscopy has been used to determine the and concentrations of electroless Ni plating baths. The 31P NMR resonances of and are narrow and resolvable in alkaline solution, appearing at +8.0 and +4.7 ppm with respect to neat phosphoric acid, and are the only resonances detected in fresh and spent plating bath solutions. In the presence of proton coupling, these resonances appear as multiplets due to direct proton coupling, with characteristic coupling constants: for and = 566.4 Hz for . Although the compositions of alkaline baths can be monitored without additional sample treatment, the phosphorus resonances in acid baths are broad and overlapped indicating that the phosphite anions can compete and exchange with solvent molecules for solvation positions about the paramagnetic Ni2+. Strong Ni2+‐complexing agents, like EDTA2− and , are effective in displacing the phosphorus‐containing ligands from the Ni2+ coordination sphere, thus permitting species determination by 31P NMR. Compositions of the phosphorus species of Ni plating baths obtained by this method are reported and compared to results obtained by the traditional titration method. Monitoring of the and levels as a function of bath use is demonstrated using this approach.

High efficiency SnO2/n-Si and In2O3:Sn/n-Si solar cells have been fabricated which when encapsulated in EVA (ethylene vinyl acetate copolymers) and kept at temperatures below 200 °C exhibit long-term stability. However, in the absence of proper encapsulation or at high temperatures, it is possible for the properties of heterojunction SnO2/n-Si and In2O3:Sn/n-Si solar cells to suffer degradation through two distinct mechanisms, one optical and the other thermal in nature. In either case, losses in Voc can be correlated with changes in the dark current-voltage characteristics: light stress increases the dark saturation current J0, while heat stress decreases the diode quality faction n. Both degradation mechanisms are related to changes in the stored charges in the SiOx interphase region between the conducting oxide and the silicon. The thermal process is only relevant for temperatures above 300 °C, while the optical process is only evidenced if ultraviolet light is incident on the cell. Thus, cells kept at T<200 °C behind a suitable UV-absorbing filter remain stable indefinitely.

Optimization of the spray-deposition process, metal-grid pattern, and AR properties of SnO/sub 2/ and ITO films have yielded high efficiency SnO/sub 2//n-Si and ITO/n-Si cells. An efficiency of 14.6% has been achieved for a 4.2 cm/sup 2/ ITO/n-Si cell. And for large area (20 cm/sup 2/) cells the authors have obtained efficiencies of 13.6% and 13.8% for SnO/sub 2//n-Si and ITO/n-Si cells, respectively. High efficiency modules consisting of 2-inch diameter cells connected in series were made and shown to be compatible with the standard EVA encapsulation process used for p-n junction silicon cells. The authors have found that the UV-induced degradation in V/SUB oc/ can be restored by low temperature annealing. Many UV light absorbing material placed in front of the cells can eliminate degradation. In particular, SnO/sub 2//n-Si and ITO/n-Si cells encapsulated in EVA do not show any decrease in V/SUB oc/ and efficiency over an extended period of sunlight exposure.

Grain boundary barriers play a dominant role in the transport properties of polycrystalline silicon. As a result, resistivity and Hall measurements in polysilicon, when interpreted in the normal manner used for single crystals, do not represent in general the same physical entities as in single crystals. The bulk of the grain is more conducting and has a larger free carrier concentration than the barrier. However, the Hall voltage, from which the carrier concentration and mobility are computed, arises from both the bulk and the barrier region. For small grains (< 10μm) the contribution to the Hall voltage from the barrīer region is dominant, while for large grains (≥ 100μm) the bulk dominates. There is a transition region between the two. The magnitudes of the contributions depend on the relative size and resistivity of the grain and the boundary. Thus the interpretation of the data varies with grain size. Doping also affects the relative contribution of the bulk and barrier regions. It is not necessary to invoke carrier depletion within the grain to account for the observed mobility minimum.

The objectives of the project are: 1) to develop cell fabrication procedures to further define the maximum capabilities of the conducting oxide/silicon heterojunction solar cells; 2) to optimize the spray fabrication technique for making reproducible high efficiency cells; 3) to assess the stability and the projected lifetime of the cell structure; 4) to identify through appropriate measurements the effects of grain boundaries and intragrain defects on the electronic transport mechanisms in thin-film polycrystalline silicon; and 5) to determine the feasibility of a large-scale fabrication process. Progress is reported.

Upon electrolysis of aqueous zinc bromide solutions containing unsymmetrically substituted, cyclic quaternary ammonium bromides, both zinc metal and a bromine‐rich liquid are produced. Data, reported for N‐ethyl, N‐methylmorpholinium (1), N‐methoxymethyl, N‐methylpiperidinium (2), and N‐chloromethyl, N‐methylpyrrolidinium (3) bromides suggest that the bromine‐rich liquid is a fused salt and separates from the aqueous solution because of insolubility and density differences. The separation process of the bromine fused salt from the aqueous solution is represented as a partitioning of bromine between two phases and is dependent upon electrolysis state‐of‐charge, quaternary ammonium bromide, bromide ion concentration, and temperature. The bromine‐fused salts have properties dependent on composition. Selected examples of densities, specific resistances, viscosities, and polarization are given. Bromine, in the form of a dense, stable, conductive liquid, is useful in circulating zinc‐bromine batteries.

The effects of grain size on Hall measurements in polycrystalline silicon are analyzed and interpreted, with some modifications, using the model proposed by Bube. This modified model predicts that the measured effective Hall voltage is composed of components originating from the bulk and space-charge regions. For materials with large grain sizes, the carrier concentration is independent of the intergrain boundary barrier, whereas the mobility is dependent on it. However, for small grains, both the carrier density and mobility depend on the barrier. These predictions are consistent with experimental results of mm-size Wacker and μm-size neutron-transmutation-doped polycrystalline silicon.

An ambient temperature, rechargeable lithium/titanium disulphide cell with a lithium thiocyanate-1,3dioxolane (DOL)-1,2-dimethoxyethane (DME) organic electrolyte was investigated. Electrolyte compositions of 2.5–3.5 molal LiSCN in solvent compositions from 100% DOL to 0.80∶0.20::DOL∶DME were tested. NMR, infrared spectroscopy and linear-sweep voltammetric studies indicated that the electrolyte was thermally and electrochemically stable, except for the slow formation of dioxolane oligomers. Test cells contained 10–30 mAh cm−2 of TiS2 with two- to sixfold excess of Li in parallel-plate, prismatic configuration. Performance delivered 80–90% of theoretical charge on first discharge and showed not only a rate-dependent cycle life, but also sensitivities to the (anode loading)/(cathode loading) ratio and cathode charge density. Cells with 10–15 mAh cm−2 of TiS2 and four to sixfold excess Li operated 35–50 cycles atC/5 toC/15 rates, while 30 mAh cm−2 cathodes with 3∶1 ∶∶anode: cathode ratio cycled 10–20 cycles atC/10. Results of half-cell studies, performance variation with temperature and overcharge and overdischarge behaviour of the cells are presented. Possible causes of the loss of efficiency during cycling are discussed.