Abstract:In this study, biodegradable microparticles of silk fibroin (SF)/chitosan (CS) blends with SF/CS blend ratios of 1:0, 2:1, 1:1, 1:2 and 0:1 (w/w) were prepared using the water-in-oil emulsification-diffusion method without any surfactants. An aqueous SF/CS blend solution and ethyl acetate were used as the water and oil phases, respectively. The plain SF had an irregular shape, while the CS microparticles were spherical. The blend microparticles were spherical in shape with a rough surface. Average microparticle sizes were in the range of 73-80 μm. The microparticle matrices had a sponge-like morphology. Conformational changes in the SF component, from random coil to the β-sheet form, were observed in the FTIR data. The dissolution of the blend microparticles was lower than those of the plain SF and CS microparticles. Microparticle density steadily increased and porosity slightly decreased as the amount of CS in the blend increased.
Summary: Organically modified montmorillonite (o‐MMT) in a room temperature addition cured silicone elastomer (PDMS) has been found to control the release of 2,4,2′‐trichloro‐2′‐hydroxy diphenylether (triclosan (TCS)) from the composite. The effect of o‐MMT gallery polarity on controlled release was investigated via different intercalants and the interaction of triclosan with the o‐MMT was investigated using flow micro‐calorimetry (FMC). The latter was found not to be a universal predictor of controlled release activity of the composite as combined TCS and PDMS interactions with MMT/o‐MMT leading to intercalation (observed using WAXS) and controlled release activity must also be considered. Southern Clay Products Cloisite® 15A (C15A) gave the most sustained release of TCS whilst also featuring a uniform gallery spacing in the composite. A pore structure based on self‐assembled C15A intercalant alkyl tails is tentatively proposed.
The stereocomplex polylactides (scPLAs) of the asymmetric poly(L-lactide)(PLLA)/poly(D-lactide) (PDLA) ratios from 80:20 to 60:40 were prepared via the simple melt blending method using an internal mixer at 200°C. An organo-modified clay, Cloisite® 30B, was used for nanocomposite preparation. The formation of the stereocomplex and nanocomposite structures were confirmed by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). An increase in the PDLA content could enhance the stereocomplex formation. The presence of Cloisite®30B decreased the melting temperature and crystallinity of the blends. This was due to the thinner crystalline size generated and/or more disordered crystals.
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