SC-ISE

Infrared synchrotron micro-spectroscopy is also an appropriate method for identifying and visualizing the existence of localized water at buried interfaces, particularly between multilayers of polymers. It was recently shown that water inclusions can be imaged at the buried interface of solid-contact-ion-selective electrodes (SC-ISEs) [22]. In this study a poly(methyl metha-crylate)-poly(decyl methacyrlate) [PMMA-PDMA] copolymer was used. Since the PMMA-PDMA copolymer is known to be water repellent and unsuitable for water sorption at measurable levels in the bulk membrane, the detection (or non-detection) of water by reflectance SR-FTIR is symbolic of the presence (or absence) of localized zones of water at the buried interface of a solid-contact ISE employing PMMA-PDMA as the sensing membrane. In fact, SR-FTIR revealed the presence of micrometer-sized inclusions of water at the gold-to-membrane interface, whereas coupling a hydrophobic solid contact of poly(3-octylthiophene 2,5-diyl) (POT) prevented the accumulation of water at the buried interface (Fig. 2) [22]. 

Solid-state electrodes include devices in which the inner solution has been completely eliminated. The solution can be replaced with an all-polymer membrane formed directly on a metal reference electrode (CWE) a system of plasticized PVC (BMSA) or a substance with ionic-electron conductivity, a conductive polymer (SC ISE). 

Solid-contact ion-selective electrodes (SC-ISEs) are produced through direct application of a conductive polymer on an electron conductor (redox electrode) through electropolymerization, and then application of a thin film, typically a polymer (PVC) ion-selective membrane. 

As a part of the electrodes used in galvanic cells, the role of direct (internal) contact is to facilitate communication between the meter and the electrochemical cell. This is usually sohd contact (SC) and is referred to by names such as solid contact irai-selective electrodes (SC ISEs) or sohd contact reference electrodes (SC REs). The main reason for introducing sohd contact into indicator/working or reference electrodes is to eliminate their watery compartments, often called internal solution. This soluticm can be an obstacle in many appHcations where there are restrictive maintenance and/or service demands (e.g., in clinical chemistry), there is contamination of the sample by a leakage of the internal soluhon (e.g., in cellular biology), there is a need for other than a vertical position (e.g., in industrial process analysis), or specific reference electrode shapes (e.g., in disposable chnical analyzers) are required. 

The solid contact in the electrodes should correspondingly, in SC ISE and SC RE, support these two roles. 

The coated-wire ISEs represented the first major approach to the fabrication of SC ISEs based on polymeric manbranes. These electrodes involved coating the reference element directly with the ISM without having a thermodynamically defined interface, which obviously impeded their long-term potential stability. The failure of this straightforward approach in a number of practical... 

The slight CO2 sensitivity of 3DOM carbon-based solid contacts is similar with that of PEDOT SC ISEs (ca. 10 mV/h) and significantly less than of PPy-based ISEs (ca. 30 mV/h). 

S. Martin, J. Ha, J. Kim, T. Strong, G. Cha, and R. Brown, ISE arrays with improved dynamic response and lifetime, in Tech. Digest of the Solid-State Sensor, Actuator, and Microsystems Workshop, pp. 396-399. Hilton Head, SC (2004). 

At this point, we mention a further consequence of the universality principle alluded to above. For each universality class (such as that of the Ising model or that of the XY model, etc.) not just the critical exponents are universal, but also the scaling function F(H), apart from non-universal scale factors for the occurring variables (a factor for H we have expressed via the ratio C/B in eq. (84), for instance). A necessary implication then is the universality of certain critical amplitude ratios, where all scale factors for the variables of interest cancel out. In particular, ratios of critical amplitudes of corresponding quantities above and below Tc, A+j A [eq. (7)], C+jC [eq. (6)] and f+/ [eq. (38)] are universal (Privman et al., 1991). A further relation exists between the amplitude D and B and C 1 Writing M H -> oo) = XHl/ cf. eqs. (87) and (91), the universality of M(H) states that X is universal. But since 0 = B tfM H) = B t PXH = B] SC S H] X, a comparison with eq. (45) yields... 

Note that all these formulas also contain the result for the limiting case of short chains dynamics described by the Rouse model [139,140] if we formally put NjSsN in these equations. As will be discussed later (Sect. 2.5), there occurs a crossover in the static critical behavior from mean-field-like behavior where ocR e" with e = 1 — x/Xcrit> Sc u(0)cx N e to the nonclassical critical behavior with Ising model [73, 74] critical exponents cc8 , S ii(0) oce , vwO.63, y 1.24. This crossover occurs, as predicted by the Ginzburg criterion [76-79,148] for Ec°c 1/N or [78,9], equivalently for ccRg, N. It thus is seen that for N, = N the crossover from non-mode-coupled dynamics (for /R, to mode-coupled dynamics (for /R, P, /N) and the crossover... 

Detected ions Potentiometry with mebr. ISE Amperom. Condr Suppr. ictivity SC Direct uv Indirect... 

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