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Binary polymeric mixtures containing pluronic F127 (PF) and methylcellulose were prepared to generate new thermosensitive matrices. The small-angle X-ray scattering (SAXS) behavior of PF/MC blends was investigated in relation to the temperature-dependent phase transition and rheological characteristic. Although 11% w/w PF (11PF) cannot form gel, the test tube tilting method and rheological analysis showed that the incorporation of 4% w/w methylcellulose (MC) into 11PF (11PF/MC) enabled the system to form gel upon heating. In addition, adding MC lowered the gelation temperature of 17% w/w PF (17PF). The ordered structure of these gels exhibited a face-centered cubic phase at intermediate temperature above the gelation temperature; the steep upturn of the SAXS curves was observed in the small scattering vector range at high temperatures (55–70 °C). The presence of MC might cause an MC-assisted interconnected network of micelles. At high temperatures, the gelation possibly involved MC-assisted intermicellar organization of PF as well as the gel network of MC. Etidronate sodium was incorporated into the matrices, and the drug did not significantly affect the thermosensitive gelation and the ordered structure of the polymeric systems. Furthermore, this study indicated that 11PF/MC was sol at 25 °C and became gel at body temperature of 37 °C. Therefore, blending PF with MC is a potential strategy for tailoring the thermosensitive performance of the in situ gelling preparation for drug delivery. [ABSTRACT FROM AUTHOR]

This study is the first report on the preparation of mesoporous carbon/silica (MCS) nanocomposites with tunable mesoporosity and hydrophobicity using natural rubber (NR) as a renewable and cheap carbon source. A series of mesoporous nanocomposites based on NR and hexagonal mesoporous silica (HMS) were prepared via an in situ sol–gel process and used as precursors; then, they were converted into MCS materials by controlled carbonization. The NR/HMS precursors exhibited a high dispersion of rubber phase incorporated into the mesostructured silica framework as confirmed by small-angle X-ray scattering and high-resolution transmission electron microscopy. An increase in the carbonization temperature up to 700 °C resulted in MCS nanocomposites with a well-ordered mesostructure and uniform framework-confined wormhole-like channels. The NR/HMS nanocomposites possessed high specific surface area (500–675 m2 g−1) and large pore volume (1.14–1.44 cm3 g−1). The carbon content of MCS (3.0–16.1 wt%) was increased with an increase in the H2SO4 concentration. Raman spectroscopy and X-ray photoelectron spectroscopy revealed the high dispersion of graphene oxide-like carbonaceous moieties in MCS materials; the type and amount of oxygen-containing groups in obtained MCS materials were determined by H2SO4 concentration. The enhanced hydrophobicity of MCS nanocomposites was related to the carbon content and the depletion of surface silanol groups, as confirmed by the water sorption measurement. The study on the controlled release of diclofenac in simulated gastrointestinal environment suggests a potential application of MCS materials as drug carriers. [ABSTRACT FROM AUTHOR]

The effect of adding GA to 1 % (w/v) TSX on the phase transitions was detected by tube inversion and optical changes. The size of the aggregated domains and the morphology of the GA/TSX blends in the gel states were investigated using SAXS and an optical microscope, respectively, at 25 °C. Turbidity and tube inversion determinations showed that 1TSX, 0.2GA/1TSX and 0.4GA/1TSX could not form a gel but the blends of 0.6GA/1TSX, 0.8GA/1TSX and 1GA/1TSX formed turbid gels and exhibited a thermoreversible phase transformation. Upon heating, the gel-to-sol temperatures were between 42 and 52 °C and increased with an increase of the GA concentration. Upon cooling, the sol-to-gel temperatures were between 26 and 36 °C with the lower temperatures for the lower concentrations of GA in the blends. According to SAXS analyses, molecular aggregation appeared in the blends that exhibited the gelling ability with an aggregation domain of 2.2-2.9 nm. The size of the aggregation domain increased as the GA concentration increased. Fibrillation was observed for the gels of 0.6GA/1TSX, 0.8GA/1TSX and 1GA/1TSX from the optical micrographs. Furthermore, the blends of GA/TSX caused synergistic antioxidant activity as determined by a reduction of the DPPH radicals. In addition, these GA/TSX gels exhibited a sustained release of GA by a non-Fickian mechanism. These gels may have a potential use for the topical delivery of GA. [ABSTRACT FROM AUTHOR]

The loading and morphology of zinc oxide (ZnO) affect the bonding and segmentation in commercial polyurethane (PU) coatings. By virtue of surface modification, hexagonal ZnO microprisms can be uniformly dispersed in PU matrix even at a loading as high as 25 wt%. However, the disruption of ZnO fillers can be observed with the suppression of characteristic PU absorption bands in Fourier transform infrared (FT-IR) spectra and the enthalpy reduction in differential scanning calorimetry (DSC) thermograms. The morphological effect is highlighted by the significant changes in DSC and FT-IR spectra when hexagonal ZnO is substituted with the sword-like counterpart. The results suggest that more sword-like ZnO can be loaded in PU coatings with a less disruption in bonding and segmentation. [ABSTRACT FROM AUTHOR]