Polymers derived from cyclodextrins show several biomedical applications. In this paper, six cross-linked polyurethane networks based on b-cyclodextrin (bCD) or hydroxypropyl-b-cyclodextrin (HPbCD) and polyethylene glycols (PEG 400, PEG 1500 or PEG 4000) were synthesized by the usual two-step polymerization method. The polymers were characterized by Fourier-transformed infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The inclusion capacity was evaluated by the discoloration method of a phenolphthalein solution. In order to explore their potential use as controlled drug delivery systems, dissolution profiles and release behavior of inclusion complexes between PUR/TDI/ bCD/PEG4000 or PUR/TDI/HPbCD/PEG1500 and nifedipine (NIF) were investigated. FTIR assignments confirmed the formation of urethane linkages. XRD patterns revealed that the crystallinity decreased mainly due to the crosslinking process. TGA showed three stages of mass loss attributed to water loss, cleavage of urethane bonds and volatilization of decomposition products. The inclusion capacity of cyclodextrins cross-linked with polyurethane was suitably maintained. Dissolution profiles demonstrated that the inclusion complexes PUR/TDI/bCD/PEG4000-NIF and PUR/TDI/HPbCD/PEG1500-NIF are feasible systems for controlling drug release, showing a biexponential release behavior.
Biodiesel can be obtained by transesterification of the triglycerides present in the vegetable oil and animal fat. After the reaction it is necessary to purify the alkyl esters. One way to obtain this is making the dry wash. Thus, this study proposes the preparation of polyurethane foams with maltodextrin as sorbents for use in the biodiesel purification. The foams were prepared and characterized by ATR-FTIR, TGA, DSC and water absorption test (ASTM D570). The FTIR spectra showed typical bands of polyurethane, TGA curves showed weight loss in two stages, the DSC analysis of the foams based on maltodextrin revealed a Tg value higher than that observed for the control foam, moreover, the absorption test in water showed that the foams based on maltodextrin showed a more hydrophilic character. The efficiency of the foams as possible sorbents for biodiesel purification was monitored by two indicators: soap concentration (AOCS Cc 17-19) and acidity index (AOCS Ca 5a-40). The results indicated that the foams were promising candidates in the removal of contaminants.
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