1,721,001 research outputs found
Synthesis and characterization of pendant carboxylic acid functional poly(lactic acid) and poly(lactic acid-co-glycolic acid) and their drug release behaviors
No full textThe carboxylic acid functionalized biodegradable aliphatic polyesters were prepared by ring-opening polymerization of L-lactide and glycolide with 2,2'-bis(hydroxymethyl propionic acid) (HMPA) as an initiator. The polymers were characterized by FT-IR, H-1-NMR and gel permeation chromatography (GPC). Molecular weights of homopolymers and copolymers ranged from 0.28 X 10(4) to 11 X 10(4) and decreased with increasing weight fraction of HMPA in the feed. Moreover by changing the HMPA content, the solubility and degradation behavior of resulting polymers could be varied. Environmental scanning electron microscopy (ESEM) studies revealed that the microspheres were spherical in shape and had a smooth surface texture. For the investigation of drug release behavior of biopolymers, Lidocain was used as a model ionic drug. It was observed that an increase in drug loading reduces the encapsulation efficiency. After the initial burst, the release rate of the drug increased with time, with most of the drug released within 15 days. Copyright (c) 2005 John Wiley & Sons, Ltd
Semi-interpenetrating hydrogel networks of poly(2-hydroxyethyl methacrylate) with poly[(D,L-lactic acid)-co-(epsilon-caprolactam)]
No full textİyoni̇k sivi destekli̇ pvdf poli̇elektroli̇tleri̇n kontrollü poli̇meri̇zasyon İle hazırlanması ve karakteri̇zasyonu
No full textSwelling and diffusion studies of poly(N-isopropylacrylamide/itaconic acid) copolymeric hydrogels in water and aqueous solutions of drugs
No full textN-Isopropylacrylamide/itaconic acid hydrogels (NIPAAm/IA) containing different amounts of itaconic acid prepared by irradiating with gamma-radiation were used in experiments on swelling and diffusion of the model drugs methylene blue, lidocaine, and sildenafil citrate (VIAGRA). The NIPAAm/IA hydrogels containing 0-3 mol % itaconic acid irradiated at 48 kGy has been used for swelling and diffusion studies in water and aqueous solutions containing the above-mentioned model drugs. For these hydrogels, swelling studies indicated that swelling increased with the following order: water > lidocaine > methylene blue > VIAGRA. Diffusions of water and the drugs within hydrogels were found to be non-Fickian in character. (C) 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 911-915, 2004
Semi-interpenetrating hydrogel networks of poly(2-hydroxyethyl methacrylate) with poly[(D,L-lactic acid)-co-(epsilon-caprolactam)]
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Isosorbide, pyrogallol, and limonene-containing thiol-ene photocured bio-based organogels for the cleaning of artworks
Full text linkThe development of bio-based gels for the cleaning of historical artworks is an attractive area of re-search. In this work, we designed thiolene photocured organogels by combining five different thiol or allyl functionalized bio-based monomers. Isosorbide, pyrogallol, and limonene were used as the bio-based building blocks for derivatization. The chemical structures of the synthesized monomers were characterized by proton nuclear magnetic resonance spectroscopy (H-1 NMR) and Fourier transform infrared (FTIR) spectroscopy. The organogel structures were examined by FTIR analysis. Thermal and thermomechanical properties of the gels were determined by thermogravimetric analyses (TGA) and dynamic mechanical analysis (DMA), respectively. The swelling behavior of the organogels in various solvents was also investigated. Gels swelled most in dimethyl carbonate (DMC). The confinement of the solvents in the gels de-creased their evaporation rate. The organogels displayed a two-stage degradation profile and were found to be thermally stable up to & SIM;200 & DEG;C. The gels were evaluated for the cleaning of dammar-based varnish from historical artwork. DMC swollen gels were found to be effective in removing the varnish from the surface of the artwork. None of the prepared gels adhered to the surface layer of the paintings. Scanning electron microscope (SEM) images proved that the surfaces were cleaned without leaving any gel residue. (C) 2022 Elsevier Masson SAS. All rights reserved
Polyimide-silica hybrid coatings: morphological, mechanical, and thermal investigations
No full textIn this study, polyimide-silica (PI-silica) based hybrid coating compositions were prepared from tetraethoxysilane (TEOS), gamma-glycidyloxypropyl trimethoxy silane (GOTMS), and polyamic acid (PAA) via a combination of sol-gel and thermal imidization techniques. PAA was synthesized from 3,3 ',4,4 '-benzophenone tetracarboxylic dianhydride (BTDA) and 3,3 '-Diaminodiphenyl sulfone (DDS) in N-Methyl-2-pyrrolidone (NMP). The silica content in the hybrid coatings was varied from 0 to 20 wt%. The structural characterization of the hybrid coatings was performed using FTIR and Si-29-NMR spectroscopies. Results from both pendulum hardness and micro indentation test show that the hardness of hybrid coatings improves with the increase in silica content. The tensile tests also demonstrated that the mechanical properties at low silica content are rather striking. Their surface morphologies were characterized by scanning electron microscopy (SEM). SEM studies revealed that inorganic particles were distributed homogenously through the PI matrix. It was also found that, incorporation of the silica domains increased the thermal stability of the hybrid coatings. Copyright (C) 2007 John Wiley & Sons, Ltd
Investigation of drug release from thermo- and pH-sensitive poly(N-isopropylacrylamide/itaconic acid) copolymeric hydrogels
No full textN-Isopropylacrylamide/itaconic acid copolymeric hydrogels were prepared by irradiation of the ternary mixtures of N-isopropylacrylamide/itaconic acid/water by gamma-rays at ambient temperature. The dependence of swelling properties and phase transitions on the comonomer concentration and temperature were investigated. The hydrogels showed both temperature and pH responses. The effect of comonomer concentration on the uptake and release behavior of the hydrogels was studied. Methylene blue (MB) was used as a model drug for the investigation of drug uptake and release behavior of the hydrogels. The release studies showed that the basic parameters affecting the drug release behavior of the hydrogels were pH and temperature of the solution. Copyright (C) 2004 John Wiley Sons, Ltd
Preparation of well-defined chitosan nanofibers by atom transfer radical polymerization
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Anticancer drug release from poly(N-isopropylacrylamide/itaconic acid) copolymeric hydrogels
No full textThe drug uptake and release of anticancer drug from N-isopropylacrylamide/itaconic acid copolymeric hydrogels containing 0-3 mol% of itaconic acid irradiated at 48 kGy have been investigated. 5-Fluorouracil (5-FU) is used as a model anticancer drug. The effect of 5-FU solution on swelling characteristics of PNIPAArn and P(NIPAAm/IA) copolymeric hydrogels have also been studied. The percent swelling, equilibrium swelling, equilibrium water/5-FU content and diffusion constant values are evaluated for poly(N-isopropylacrylamide) (PNIPAAm) and poly(N-isopropylacrylamide/itaconic) (P(NIPAAm/IA)) hydrogels at 130 ppm of 5-FU solution at room temperature. Diffusion of 5-FU solution into the hydrogels has been found to be the non-Fickian type. Finally, the kinetics of drug release from the hydrogels are examined. (c) 2004 Elsevier Ltd. All rights reserved
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