A combined experimental and theoretical study of phase behavior and structure in binary systems of block copolymers and a selective solvent is presented. The block copolymers used here consist of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO), and the solvent is water, selective for the PEO block. The concentration−temperature phase diagrams of (EO)8(PO)47(EO)8 (Pluronic L92) and (EO)11(PO)70(EO)11 (Pluronic L122) in water have been determined experimentally. These two block copolymers are unique in that they form both normal (H1, “oil-in-water”) and reverse (H2, “water-in-oil”) hexagonal lyotropic liquid crystalline structures in binary systems with water over the same temperature range. This is the first time the H2 structure is reported in a binary PEO−PPO−PEO/water system. Thereafter, the predicted phase diagram of (EO)20(PO)69(EO)20 in water is given, employing a self-consistent mean-field lattice theory with internal degrees of freedom. The free energy for a number of possible microstructures was calculated as a function of the polymer concentration, and the extensions of the one-phase and two-phase regions were established. The model predicted the composition and temperature stability ranges of disordered solution, micellar solution, normal hexagonal, lamellar, reverse hexagonal, and reverse cubic ordered phases which appeared at increasing (EO)20(PO)69(EO)20 concentration, in good agreement with the experimental Pluronic L122 phase behavior. Moreover, the model provides the volume fraction profiles for the PEO, PPO, and water components in the self-assembled microstructures, information which is not readily accessible from experiments. Finally, an increased segregation among the species and an increased domain spacing at increasing polymer length were found. The data are consistent with the scaling behavior predicted for the domain size in weakly segregating block copolymer systems.

We could show that the amount of drug escaping filtration in a realistic throat model under realistic delivery conditions predicts the typical total lung deposition in trained healthy adult subjects in the absence of significant exhaled mass. We could further show that by using combinations of throat models and flow profiles that represent realistic deviations from the typical case, variations in ex-cast deposition reflect between-subject variation in lung deposition. Further, we have demonstrated that ex-cast deposition collected either by a simple filter or by a cascade impactor operated at a fixed flow rate using a mixing inlet, to accommodate a variable flow profile through the inhaler, predicts equally well the lung deposited dose. Additionally, the ex-cast particle size distribution measured by this method may be relevant for predicting exhaled fraction and regional lung deposition by computational models.

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Ternary poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO)/ water/oil systems have been studied theoretically with a lattice mean-field theory. Phase diagrams for three PEO-PPO-PEO block copolymers are presented, and the existence of the ordered cubic micellar, hexagonal, lamellar, reverse hexagonal, and reverse cubic micellar phases as well as disorded water-rich and water-poor phases was considered. It was found that the length of the EO blocks strongly affected the phase behavior. The lamellar phase was studied in more detail with respect to the domain spacing and interfacial area per PEO block at different compositions and to the polymer conformations. The degree of looplike conformations and of bridging conformations across the apolar domain (PO + oil) was found to be dependent on the apolar domain thickness. Comparison with experimentally determined phase diagrams and lamellar domain spacings was also made.