Infinite-Dilution Activity Coefficients of Polar and Nonpolar Solvents in Solutions of Hyperbranched Polymers

Abstract

Infinite-dilution activity coefficients are measured for several polar and nonpolar solvents in hyperbranched polymers using inverse gas chromatography in the temperature range 40-160 °C. Two kinds of polymers are studied: comb polymers and dendritic polymers. The combs are poly(styrene-co-maleic anhydride) with alkyl side chains of different lengths (C12, C22). The solvents are: acetone, toluene, tetrahydrofuran (THF), and chloroform. Solvent solubility in the combs depends on the ratio between the polar backbone and the nonpolar side chain of the polymer. The dendrimers are amine-terminated poly(propylenimine) of generation 2 to 5. The solvents are: methanol, ethanol, ethyl acetate, toluene, and THF. Solvent activity coefficients change with respect to the dendrimer generation number, reaching a minimum at generation 4. Because the dendrimers are basic, the solvent quality is higher for slightly acidic solvents, such as methanol and ethanol. Flory's interaction parameters are calculated for the solvent/dendrimer systems.

Dendritic Polymers - Interdisciplinary Research and Emerging Applications from Unique Structural Properties

“…Polese et al reported measurements of infinite-dilution activity coefficients for polar and nonpolar solvents in comb polymers and polypropylenimine dendrimers of generation 2 to 5 [40]. Solvent activity coefficients at infinite dilution change with respect to the dendrimer generation number, reaching a minimum at generation 4 in the temperature range 333 to 413 K [40].…”

“…Solvent activity coefficients at infinite dilution change with respect to the dendrimer generation number, reaching a minimum at generation 4 in the temperature range 333 to 413 K [40]. Due to the exothermic formation of hydrogen bonding, alcohols can form hydrogen bonds with the dendrimer more easily at low temperatures and hence the solubility decreases with increasing temperature [40]. Since Polese et al used dendrimers with a basic character, slightly acidic solvents showed better solvent qualities than others (THF, toluene, ethyl acetate).…”

Measurements of mass-fraction activity coefficient at infinite dilution of aliphatic and aromatic hydrocarbons, thiophene, alcohols, water, ethers, and ketones in hyperbranched polymer, Boltorn H2004, using inverse gas chromatography

“…poly(styrene-co-maleic anhydride), or C 22 esterified poly(styrene-co-maleic anhydride)], using IGC were presented [32,33]. The values of the mass-fraction activity coefficient for these polymers X 1 12 were (at very high temperatures T > 360 K) from 3 to 40.…”

Temperature Dependent Studies of Molecular Interactions in a Low‐Molecular Weight Ester Diol Mixed with a Hyperbranched Polyester Additive

“…As opposed to our findings, which showed an increase in solubility with increasing temperature, it is reported that due to the exothermic formation of hydrogen bonding, alcohols can form hydrogen bonds with dendrimers more easily at lower temperatures and hence solubility decreases with increasing temperature. [41] Temperature dependent IR measurements could be used to prove the assumption that the weakening of H bonds is responsible for structural changes in the ester diol. The IR spectra of the pure hyperbranched polyester, the pure ester diol and the blend of ester diol with 1% of the hyperbranched polyester in the full mid-infrared spectral region at 25 8C are given in Figure 6.…”