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pH-Sensitive organic-inorganic copolymers of hydrogels were developed as drug delivery systems (DDS) to improve the swelling behavior of polyacrylic acid (PAA). They were represented through FTIR, TGA and XRD characterization which revealed that the functional groups of methacryl-phenyl polyhedral oligomeric silsesquioxane (POSS) were successfully added to the acrylic acid (AA) molecular chains through radical solution polymerization. The DSC test results indicate that the addition of POSS could improve the thermal properties of the copolymers. The swelling properties at the pH range of 1.25-8.01 exhibited the pH sensitivity of POSS/AA copolymers (POSS- co-AA) and the lower swelling ratio in acidic conditions indicated that the DDS had low amount of release in SGF; this phenomenon suggested that the copolymer was available as DDS of theophylline. And it was proved by drug release curve and scanning electron microscopy. Since the addition of POSS reduced the release rate of theophylline and prolonged the release time of the drug, the concentration range of theophylline could remain low for an extended duration. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

Organic–inorganic nanocomposites comprising epoxy resins and polyhedral oligomeric silsesquioxanes (POSS) were prepared via in situ polymerization of 3,3′,5,5′-tetramethyl-4,4′-biphenyl diglycidyl epoxy resins and 4,4′-diaminodiphenylsulfone. The thermal, fire-retardant, and morphological properties of the nanocomposites were studied using thermogravimetric analysis (TGA), thermogravimetry-Fourier transform infrared (TG-FTIR) spectroscopy, microscale combustion calorimeter (MCC), limiting oxygen index (LOI), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The peak heat release rate and the total heat release were significantly reduced with the incorporation of POSS into the epoxy networks, based on the MCC results. Moreover, the LOI value slightly increased with the increase in POSS content. Further, SEM and XPS were used to explore the char residues of the pure epoxy resin and POSS-containing system. The introduction of POSS was found to lead to the formation of an inert layer on the surface of the materials, which protects the internal structure from decomposition. [ABSTRACT FROM AUTHOR]

A series of hybrid polymers based on methacrylphenyl polyhedral oligomeric silsesquioxanes (MA-POSS) and methylmethacrylate (MMA) were rapidly synthesized via UV photopolymerization through a (2,4,6-trimethylbenzoyl)diphenylphosphine oxide-initiated reaction. The structure and morphology of hybrid polymers were characterized via Fourier transform infrared spectroscopy, proton nuclear magnetic spectroscopy, gel permeation chromatography, X-ray diffraction, transmission electron microscopy and scanning electron microscopy, which confirmed that the MA-POSS cage could be successfully incorporated into the polymethylmethacrylate (PMMA) chain. The obtained hybrid polymers had no obvious aggregation of MA-POSS. It can be concluded that MA-POSS were well-dispersed in the hybrid polymers. The thermal properties of PMMA–POSS hybrid polymers were investigated through differential scanning calorimetry and thermogravimetric analysis. Results show that the incorporation of POSS cage results in the enhancement of the glass transition temperature and the decomposition temperature of hybrid polymers as compared with PMMA polymers without MA-POSS. [ABSTRACT FROM AUTHOR]