The morphology phase diagram of biodegradable polymer blends of PDLLA, PCL, and PEO is presented and discussed. The phase diagram of PCL/high‐molecular‐weight PDLLA mixtures reveals an hour‐glass phase diagram. Upon lowering the molecular weight of PDLLA, a combined LCST/UCST develops that is intersected by the melting transition curve of PCL. The observed liquid/liquid phase separation and crystal/isotropic phase transition are compared with the theoretical liquidus/solidus curves obtained by solving the combined Flory‐Huggins and phase‐field free energies self‐consistently. A similar study is extended to the binary phase diagrams of PEO/PDLLA and PCL/PEO. Of particular interest is that the prism‐type phase diagram of the ternary blends provides a complete description of the overall phase behavior. magnified image

Genistein is a phytochemical with a broad range of desirable biological activity for wound healing. However, its poor bioavailability requires developing a new method for fabricating an appropriate carrier vehicle to deliver genistein in a sustained manner. Based on the guidance afforded by the ternary phase diagram of poly(D,L-lactic acid) (PDLLA), poly(ethylene oxide) (PEO), and genistein blends, certain selective compositions were electrospun. We obtained a uniformly smooth surface morphology in unmodified and genistein-modified PEO/PDLLA fibers, documented by scanning electron microscopy. Moreover, wide-angle X-ray diffraction and 1H NMR studies revealed that the genistein molecules, successfully incorporated in the blends, remained chemically stable after electrospinning. Besides surface wettability and dimensional stability of the electrospun mats, the released genistein amount has been evaluated as a function of PEO concentration. Our biocompatibility investigations suggest that genistein-modified PEO/PDLLA electrospun mats exhibit strong antioxidant and anti-inflammatory activities which indicate they have potential applications for wound dressings.

In an effort to alleviate the well‐known toxicity effect of phthalate derivatives on human health, genistein (G) modified epoxidized soybean oil (ESBO) has been investigated as an alternative “green” plasticizer for poly(vinyl chloride) (PVC) with potential application in medical products. As evidenced by a single glass transition that shifts systematically with composition in conjunction with the melting point depression of G crystals, ESBO is not only a good plasticizer to PVC, but also miscible with G. Moreover, ESBO is an excellent compatibilizer to the immiscible PVC/G pair. Furthermore, PVC/ESBO/G ternary blends revealed complete miscibility in the amorphous state. Of particular interest is that ESBO‐plasticized PVC is thermally curable with G at elevated temperatures above 220 °C and affords relatively stable G modified ESBO‐plasticized PVC for blood contact medical applications such as blood bags and hemodialysis tubings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46472.

Solid-liquid phase diagrams of binary crystalline blends of genistein with poly(ethylene oxide) (PEO) and poly(ethylene glycol) (PEG) were established experimentally and theoretically based on the combined Flory-Huggins free energy of liquid-liquid phase separation and the phase field free energy pertaining to crystal solidification. The liquidus lines obtained self-consistently were found to agree well with trends of depressed crystal melting transitions in genistein/PEO and genistein/PEG blends, exhibiting eutectic phase behavior. Of particular importance is the lowering of the eutectic temperature of the genistein/PEO blend by about 60 °C upon switching to the genistein/PEG system. The occurrence of interspecies hydrogen bonding between genistein molecules and both PEO and PEG chains, albeit weak, was noticed by Fourier transform infrared spectroscopy. The improved solubility of genistein in PEG can be attributed not only to lowering of the molecular weight of PEG utilized, but also to its terminal hydroxyl groups. This eutectic melting approach by PEG solvent is sufficiently effective in solubilizing genistein crystals that development of genistein-containing drugs might be feasible for injection and/or oral administration.

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