New thermosensitive hydrogels based on N-isopropyl acrylamide and 2-hydroxyethyl acrylate were prepared in the presence of ammonium persulfate as an initiator using a free-radical technique. The thermal stability as well as the physical and chemical properties of the obtained hydrogel were studied by thermogravimetric analysis, differential scanning calorimetry and scanning electron microscopy. The swelling of the hydrogels was investigated by the cathetometer method. In order to use thermosensitive hydrogels as a carrier of antibiotics (lincomycin and gentamicin), several biological tests were performed. All samples of thermosensitive poly(N-isopropyl acrylamide) and 2-hydroxyethyl acrylate hydrogels containing medical substances exhibited antibacterial activity. The antibacterial activity of temperature-sensitive hydrogels naturally increases with increasing concentration of antibiotics in the carrier. The results obtained indicate a large amount of drug was released from the hydrogels with full retention of antimicrobial properties. These copolymers can be used as an antibacterial material in the field of medicine.
Ñopolymerization of N-isopropylacrylamide (NIPAAm) with 2-hydroxyethyl acrylate (2-HEA) carried out by solvent ethanol solution method, at 60 0 C, using Azoisobutyronitrile (AIBN) as an initiator. The hydrophilic copolymers were characterized by elemental analysis, DSC, TGA and turbidimetric method. The results showed thermal stability increase with increase of NIPAAm in the copolymers. It was found that copolymer solutions have lower critical solution temperature (by turbidimetric analysis). The reactivity ratios of monomers were determined using linear methods like Fineman-Ross and Kelen-Tudos. The reactivity ratios of r 1 and r 2 were found to be 0,
Thermosensitive hydrogels based on N‐isopropylacrylamide (NIPAAm) and 2‐hydroxyl ethyl acrylate (2‐HEA) were synthesized with different composition ratios at 50:50 and 70:30 mol% using ammonium persulfate as free radical initiation system. The hydrogel was characterized by Fourier transform infrared spectroscopy (FTIR). The interpolymer complex between hydrogels and linear with poly(acrylic acid) (PAA) with different molecular weight was studied. The effect of pH, molecular weights, inorganic salt (NaCl) as well as surfactants concentrations on the complexation was investigated. The swelling behavior of the thermosensitive hydrogels in PAA solutions went up with increasing pH and molecular weight of PAA. However, the decreasing the concentration of surfactants sodium dodecyl sulfate (SDS) and cetylpyridinium bromide (CPB) increased the swelling behavior of hydrogels.
Hydrogel copolymers based on N,N-dimethyl acrylamide (DMA) and acrylic acid (AAc) were synthesized using a solution polymerization technique with different monomer ratios and ammonium persulfate as an initiator. This paper investigates the thermal stability, physical and chemical properties of the hydrogel copolymer. Testing includes Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and elemental analysis (CHNS). The copolymer composition was determined by elemental analysis, and the reactivity ratios of monomers were calculated through linearization methods such as Fineman–Ross (FR), inverted Fineman–Ross (IFR), Kelen–Tudos (KT) and Mayo–Lewis (ML). Good agreement was observed between the results of all four methods. The ratio of r1 and r2 were 0.38 (r1) and 1.45 (r2) (FR), 0.38 (r1) and 1.46 (r2) (IFR), 0.38 (r1) and 1.43 (r2) (KT), and 0.38 (r1) and 1.45 (r2) (ML). Hydrogel copolymers exhibited good thermal stability, and SEM showed three-dimensional porous structures. Antibiotic-free and antibiotic-loaded hydrogels demonstrated antimicrobial properties against both Gram-positive and Gram-negative bacteria. As the ratio of DMA in hydrogel copolymer increased, the activity of copolymer against bacteria enhanced. The results indicated that these hydrogels have the potential to be used as antibacterial materials.
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