Solubilities of nonvolatile solutes in polymers from molecular thermodynamics

Abstract

Because there is no simple, general method for measuring solubilities of nonvolatile solutes in a polymer, this work presents a thermodynamic framework for estimating such solubilities from infinite‐dilution distribution‐coefficient data for aqueous solutions of the solute in equilibrium with the polymer. The experimental infinite‐dilution distribution coefficient is related to that calculated from a molecular‐thermodynamic model (Flory–Huggins). The three binary Flory parameters are obtained from water–solute and water–polymer data, and from the solute's distribution coefficient. Solubilities of 19 nonvolatile aromatic solutes were estimated in three polymers: ethyl‐vinyl acetate copolymer (EVAc) with 33 (EVAc33), 45 (EVAc45) wt. % vinyl acetate content, and poly(vinyl acetate) (PVAc) at 25°C, where most of the solutes are solids. For some of these systems, predicted solubilities are compared with new experimental results. The calculations reported here may be useful for various applications, including the design of membrane processes or drug‐delivery systems, and for packaging technology for foods, chemicals, and pharmaceuticals.

High Performance Thermoplastic/Thermosetting Composites Microstructure and Processing Design Based on Phase Separation

“…Considering the fact that the heat of vaporization of a macromolecule can not be measured experimentally, it is a common practice to calculate δ using the corresponding value of the solubility parameter of its monomers as substitute. Fedor, Van Krevelen et al's group additivity, computer simulation (Lewin et al, 2010) and thermodynamic analysis (Fornasiero et al, 2002;Utracki＆Simha, 2004) are also used widely in literature. Bicerano (Bicerano, 2002) developed a topological approach to calculate δ values based on the interaction index method, whereby group contribution is not necessary, δ can be deduced based on the polymeric chemical structure.…”

The Ubiquitous Issue of Cross-Mass Transfer: Applications to Single-Use Systems

“…Flory-type isotherms are the most relevant for thermoplastics and thermosets. They are suitable not only for homo and copolymers [23,24], but also for liquids simulating bioproducts such as methanol, ethanol, isopropanol, and water-ethanol mixtures [68,69,70]. At low concentration levels, Flory isotherms are linearized and recast into dimensionless Henry isotherms:qi,j(t,x*)=Ljtrue∑k=1…mlkCi,k(t=0)pi,j(t,x*)=ki,j⋅ui,j(t,x*) for i=sA,sB and j=0…m where qi,j(t,x) is the local dimensionless partial pressure of solute i at position x and time t .…”

“…Additionally, incorrect descriptions of mass transfer can lead to biased reasoning and underestimate the real level of migration. As an example, the accumulation of apolar substances in aqueous contacting phases is likely to be underestimated either because solubility in water and back-diffusion are misrepresented [22,23,24] or because reactivities in water have been neglected [25,26,27,28,29,30]. Migration modeling reviewed in [31] has been used for decades for authorizing new substances, validating polymer recycling processes, and compliance testing in both the US and EU.…”

Off-Lattice Flory–Huggins Approximations for the Tailored Calculation of Activity Coefficients of Organic Solutes in Random and Block Copolymers

“…In our case, Table 3 shows that several solutes are solid in ambient conditions. The corrections of fugacities, expressed as the solid/ liquid ratio ( f i S /f i L ) pure i , have been tabulated for the considered solutes by Fornasiero et al 25 For a pure solid (S) or liquid (L), the fugacity of a pure condensed phase is defined as (see eq 3− 39 of Prausnitz et al 50 ):…”

“…In the next section, the main elements of the off-lattice generalized Flory− Huggins theory are presented for multicomponent mixtures as well as the set of reference data. Flory−Huggins coefficients inferred by Fornasiero et al 24 from experimental distribution coefficients between water and three ethylene vinyl acetates (EVA) 25 were chosen as validation sets. Besides their analogies with monomers and additives used in printing inks, the 19 considered aromatic solutes are nonvolatile and capable of creating multiple weak hydrogen bonds with EVA.…”