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Author: search.filters.author.Pardini, FranciscoSubject: search.filters.subject.Stimuli-sensitive polymers

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    Synthesis and swelling behavior of pH-responsive polyurethane poly(2-(diethylamino)ethyl methacrylate) hybrid materials
    (2013) Pardini, Francisco; Amalvy, Javier
    Polyurethane (PU)/poly[2-(diethylamino)ethyl methacrylate] hybrids, having a chemical bond between the PU and acrylic moieties and with different compositions, were prepared by the dispersion polymerization of 2-(diethylamino)ethyl methacrylate (DEA) in the presence of preformed PU chains with polymerizable terminal vinyl groups. The PU dispersion was synthesized accord- ing to a prepolymer mixing process by the polyaddition of isophorone diisocyanate, poly(propylene glycol), 2-hydroxyethyl methacry- late, and dimethylol propionic acid (DMPA). Then, it was dispersed in water by the prior neutralization of the carboxylic acid groups of DMPA with triethylamine, chain-extended with ethylenediamine. The effect of the DEA content on the swelling properties (water uptake and dynamic swelling degree) at different pHs and at 37�����C was determined. The samples were also characterized by Fourier transform infrared spectroscopy and modulated differential scanning calorimetry. The experimental results indicate a higher water uptake when the DEA content was increased on the hybrid materials and a significant change in the kinetics of swelling at pH 4 com- pared to those at pH 7. The water content of the hydrogels depended on the DEA content, and it was inversely proportional to the pH value. The pure PU film did not show important changes over the pH range examined in this study. The synthesized hybrids were useful as drug-delivery, pH-sensitive matrices.
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    Evaluation of pH-sensitive polyurethane 2-diethylaminoethyl methacrylate hybrids potentially useful for drug delivery developments
    (2015) Pardini, Francisco; Faccia, Paula; Amalvy, Javier
    Smart sensitive polymers have been used to improve processes in drug delivery. In this article, we evaluate the behavior of polyurethane/N,N-diethylaminoethyl methacrylate hybrids (PU/DEA) as pH- responsive polymers potentially useful for drug delivery systems development, using Rhodamine 6G (Rh6G) as a model drug. A detailed pH responsive characterization was performed by swelling studies and scanning electron microscopy (SEM). Two drug loading methods on drug release-immersion and direct loading were evaluated. The interaction between Rh6G and the polymer matrix was studied by Fourier Transform Infrared (FTIR) spectroscopy and contact angle determination. The kinetic study of Rh6G release was performed at basic and acidic pH; the mechanism of drug delivery was analyzed using Ritger-Peppas' equation. We discuss about polymer's active sites and drug's distribution through the matrix in relation to both loading methods. Results showed a pH-responsive behavior and morphological changes when pH solution varied from 9.0 to 4.0. In the immersion loading method, results indicated a higher Rh6G molecule concentration at the surface as well as ionic interaction between the drug and polymer's carboxylic groups. Release studies confirmed the pH-sensitive hybrid systems' behavior and kinetic exponent values indicated different mechanism's transport types depending on loading method and polymer composition.