The growth-starting supercooling ∆T G , defined as a supercooling at which a crystal starts to grow on cooling, was measured for the (100) face of a potassium dihydrogen phosphate (KDP) crystal on which an Al (III) impurity had been adsorbed beforehand. When adsorption was made onto the nongrowing (100) face at a low supercooling value of ∆T A ) 0.6 °C, the measured values of ∆T G were successfully explained with a mathematical model considering the Langmuir equilibrium (or instantaneous) adsorption. On the contrary, smaller values of ∆T G were obtained when adsorption was made on the growing (100) face at a high supercooling value of ∆T A ) 6.0 °C. These smaller values obtained for the adsorption at ∆T A ) 6.0 °C are concluded to be due to an insufficient amount of the adsorbed Al (III) impurity, and the adsorption is shown to proceed more slowly onto the growing (100) face compared to the nongrowing face.

The growth rate of a crystal in the presence of impurity depends on the history of supercooling. This behavior is called growth rate hysteresis (GRH). In this paper, GRH is described by using a mathematical model. This mathematical model is devised by considering the pinning mechanism of Cabrera and Vermilyea, the two-dimensional Gibbs−Thomson effect on step movement and slow adsorption of impurity species on a crystal surface. The model explains, reasonably but qualitatively, experimental literature data on GRH that its magnitude becomes large as the supercooling-changing rate R is decreased or the impurity concentration c is increased. The model also shows a possibility that the reverse effect of these two factors (R and c) on GRH may occur in the range of their small values and it predicts the GRH behavior over a wide range of experimental conditions. Limitations of the model are also discussed.

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This paper describes a reliable method to selectively produce metastable R-form glycine crystals with a controlled size in batch cooling crystallization. Seeding had a large effect both on the polymorphism and the size distribution of the product crystals. In the case of sufficient seed loadings of the R-form crystals, the metastable R-form crystals were obtained selectively as a product. Simultaneously, the crystal size distribution became unimodal with no fine crystals. However, at low seed loadings, mixtures of both the metastable R-and stable γ-form crystals were obtained. The measurement of supersaturation transient suggested that the low supersaturation caused by the growth of sufficient seeds played a key role in suppressing nucleation of the metastable R-and γ-form crystals, whereas, with no seeding, only the stable γ-form crystals were obtained. The seeding technique presented here could be a general and practical method to produce metastable polymorphs with controlled crystal size.

This paper describes the one-pot synthesis of a polyglycidol (PG)-based polymer, poly(ethoxyethyl glycidyl ether) (PEEGE)-b-[hyperbranched polyglycerol (hbPG)-co-PEEGE]x/y, its micelle formulation, and the ability to encapsulate a model therapeutic molecule. Amphiphilic block copolymers were prepared by the sequential addition of ethoxyethyl glycidyl ether (EEGE) to glycidol. The composition of the block copolymers varied from 62:38 to 92:8. Block copolymers with composition x:y≥66:34 were soluble only in organic solvents. Micelles were formulated by injection of deionized water into a tetrahydrofuran block copolymer solution with or without pyrene as a model hydrophobic molecule. The critical micelle concentration was 18.2-30.9 mg/L, and the micelle size was 100-250 nm. The pyrene-containing micelle rapidly collapsed on acidic exposure, allowing conversion of hydrophobic PEEGE to hydrophilic PG, thus, facilitating the release of the encapsulated pyrene. Cytotoxicity data showed high biocompatibility of PG-based block copolymers, suggesting their potential as a drug delivery carrier.