Determination of thermodynamic and transport properties of solvents and non solvents in poly(L‐lactide‐co‐glycolide)

Abstract

Thermodynamic properties, partition coefficient, and diffusion coefficients of the various solvents (acetone, dichloromethane, trichloromethane, ethyl acetate, ethyl alcohol, tetrahydrofuran, and water) in poly(lactide-co-glycolide) (PLGA) at infinite dilution of the solvent have been determined by inverse gas chromatography (IGC). In IGC method, which is based on the characteristic equilibrium partitioning of a solute between a mobile phase and a stationary phase, a small pulse of solvent is introduced into the column and by the aid of retention volume of the solvent, several polymer solvent interaction properties, namely retention volume (V g ), infinitely dilute weight fraction activity coefficient (O 1 1 ), Flory-Huggins interaction parameter (w), and solubility parameters of the polymer (d 1 2 ) can be determined. The thermodynamic results indicated that trichloromethane and dichloromethane were the most suitable solvents among all the solvents studied for PLGA. The partition (K) and diffusion coefficients (D p ) of various solvents at infinite dilution of the solvent were calculated by using the model developed by Pawlisch et al. (Macromolecules 1987, 20, 1564. The optimum K and D p values that best fit the data were found and the model predicted experimental data very well. So IGC method is a powerful tool for the determination of thermodynamic and diffusion properties of solvent in polymer at infinite dilution of the solvent.

Predicting the Miscibility and Rigidity of Poly(lactic-co-glycolic acid)/Polyethylene Glycol Blends via Molecular Dynamics Simulations

“…Experimental data would further support these observations in that PLGA solubility in water dramatically worsens above a certain size as it is well accepted that PLGA oligomers smaller than 1,100 g/mol are water soluble . Both values of v for PLGA in water and acetonitrile are in line with experimental polymer–solvent interactions measured by inverse gas cromatography (IGC). , …”

“… 46 Both values of v for PLGA in water and acetonitrile are in line with experimental polymer–solvent interactions measured by inverse gas cromatography (IGC). 47 , 48 …”

“…46 Both values of v for PLGA in water and acetonitrile are in line with experimental polymer−solvent interactions measured by inverse gas cromatography (IGC). 47,48 In addition to the radius of gyration, the persistence length P l was also estimated for the PEG and PLGA chains (Figure 2b), following the methods described in Section 2.3.2. Given that P l differs under Θ conditions as compared to a good solvent, 49 the persistence length of PLGA was computed in both acetonitrile and water and compared to that of PEG in water (P l = 0.37 ± 0.02 nm in good accordance with previous findings (P l = 0.37 ± 0.04 nm) (Figure 2b).…”

Microsphere-Based Seamless Scaffolds Containing Macroscopic Gradients of Encapsulated Factors for Tissue Engineering

“…Ethanol, on the other hand, is an organic solvent of higher polarity, which is arguably a more common chemical in tissue engineering protocols (applied as a sterilizing agent) and possesses an ability to physically attach aliphatic polyesters. As predicted by the Hildebrand theory involving the polymer/solvent solubility,45 ethanol is a poor solvent for PLG in comparison to dichloromethane. When ethanol came in physical contact with PLG, dissolution of a thin surface layer of PLG microspheres was previously observed,46 typically resulting in the formation of a “skin layer” or a “thin film” around the microsphere, as can also be evidenced from the SEM images (Fig.…”

Redox and thiol–ene cross-linking of mercapto poly(ε-caprolactone) for the preparation of reversible degradable elastomeric materials

“…where V so is the molar volume of the solvent (64.341 mL.mol À1 for CH 2 Cl 2 ), F p is the volume fraction of the polymer in the swollen gel equal to 1/Q w0 and c is the Flory solvent-polymer interaction parameter (c z 0.64). 29 M c,exp of 1550 g.mol À1 and 1500 g.mol À1 were calculated for EM SS and EM TH , respectively. These values are in good agreement with the theoretical molecular weight between cross-links M c,theo ¼ 1720 g.mol À1 calculated by taking into account the molecular weight of the polymer precursor and the substitution degree (Table 1).…”