Vapor‐induced swelling of supported methacrylic and siloxane polymer films: Determination of interaction parameters

Abstract

White light reflectance spectroscopy is applied to monitor vapor-induced thickness changes of polymer films, supported on suitable silicon substrates. Assuming unidirectional swelling due to the constraining support, the equilibrium volume swelling of four methacrylic polymers and two siloxane-based copolymers upon exposure to various activities of water, methanol, ethanol, and ethyl acetate vapor, at 30 C is evaluated. The deduced sorption isotherms were fitted to the Flory-Huggins equation and interaction parameters, as well as solubility coefficients at infinite solute dilution, were deduced for each binary system. The relative sorption capacity of the different classes of polymers toward the four vapors are in line with the expected solubility interactions between solvent and solute.

Capacitive sensor arrays for the real time detection of volatile organic compounds

“…The sorptive capacity of various polymeric materials, in the form of thin supported films, towards different analytes, has been previously determined by an optical methodology. Based on the deduced polymer-analyte Flory-Huggins interaction parameters, at a given water vapor concentration, PHEMA presented the highest sorptive capacity compared to different methacrylic polymers [15]. In line with these findings, at each humidity level, the response of the IDE covered with PHEMA (shown in Fig 4), is clearly higher compared to that of IDE coated with the less hydrophophilic PEMA.…”

Utilizing vapor swelling of surface-initiated polymer brushes to develop quantitative measurements of brush thermodynamics and grafting density

“…These methods can yield very different polymeresolvent interaction parameters due to the influence of concentration on that interaction parameter, and the existence of higher order interactions (such as third virial coefficients) where polymer chains self-interact, whether due to inter-chain or intrachain interaction. Vapor swelling has been used to determine c for the polymeresolvent and polymerepolymer interactions recently in conjugated [54] and crosslinked [55] polymer thin films, where overall chain solubility is poor. Recent experiments by Wagman et al evaluate swelling in monolayers of biomacromolecules in water vapor, modifying existing Flory theory to include ternary interactions between polymer, water, and vacant sites [56].…”

Polymer‐BaTiO3 composites: Dielectric constant and vapor sensing properties in chemocapacitor applications

“…The capacitance changes Δ C of a pure PBMA sensor, as well as of composite PBMA −BaTiO 3 sensors, upon exposure to 5000 ppm of each of the four analytes, are shown in Figure 9. The sorptive capacity of PBMA increases in the following order: H 2 O<MeOH<EtOH< AcOOEt, with extremely low levels of sorption of H 2 O 26. In this case, due to the reverse order of ε s , pure PBMA sensor exhibits a much lower differentiation towards the four analytes as compared with the pure PHEMA sensor, with responses Δ C moderately decreasing as we move from AcOOEt to H 2 O.…”

“…The change ΔC of the pure‐PHEMA sensor due to the corresponding changes in the dielectric constant of the polymeric layer are determined by the amount of analyte sorbed in conjunction with the latter's dielectric constant. The sorptive capacity of various polymeric materials, in the form of thin supported films, towards the four analytes studied here, has been previously determined by an optical methodology 26. On the basis of the deduced polymer‐analyte Flory‐Huggins interaction parameters, at a given analyte activity, sorption in pure PHEMA films was found to follow the order AcOOEt≪H 2 O<EtOH<MeOH.…”