Abstract
The effect of SiO2 nanoparticles on the formation of PAA (poly acrylic acid) gel structure was investigated with seeded emulsion polymerization method used to prepare SiO2/PAA nanoparticles. The morphologies of the nanocomposite nanoparticles were studied by transmission electron microscopy (TEM). Fourier-transform infrared (FTIR) spectroscopy results indicated that the PAA was chemically bonded to the surface of the SiO2 nanoparticles. Additionally, the resulting morphology of the nanocomposite nanoparticles confirmed the co-crosslinking role of the SiO2 nanoparticles in the formation of the 3D structure and hydrogel of PAA. SiO2/PAA nanocomposite hydrogels were synthesized by in situ solution polymerization with and without toluene. The morphology studies by field emission scanning electron microscopy (FESEM) showed that when the toluene was used as a pore forming agent in the polymerization process, a macroporous hydrogel structure was achieved. The pH-sensitive swelling behaviors of the nanocomposite hydrogels showed that the formation of pores in the gels structure was a dominant factor on the water absorption capacity. In the current research the absorption capacity was changed from about 500 to 4000 g water/g dry hydrogel. Finally, the macroporous nanocomposite hydrogel sample was tested as an amoxicillin release system in buffer solutions with pHs of 3, 7.2, and 9 at 37 °C. The results showed that the percentage cumulative release of amoxicillin from the hydrogels was higher in neutral and basic mediums than in the acidic medium and the amoxicillin release rate was decreased with increasing pH. Additionally, the release results were very similar to swelling results and hence amoxicillin release was a swelling controlled-release system.
Highlights
Hydrogels are a significant group of polymeric materials that are widely used in various fields of engineering and medicine such as sensors, lenses, supercapacitors, drug carriers, edible jellies, cosmetics, sanitary napkins, heavy metal ions removers, etc. [1,2,3]
According to the transmission electron microscopy (TEM) results, SiO2/PAA nanocomposite nanoparticles were synthesized with core/shell morphology
It should be noted that the amount of monomers used in the samples in Figure 1 was very low compared to other samples, and injection of more monomers into polymerization system would lead to an increase in shell thickness
Summary
Hydrogels are a significant group of polymeric materials that are widely used in various fields of engineering and medicine such as sensors, lenses, supercapacitors, drug carriers, edible jellies, cosmetics, sanitary napkins, heavy metal ions removers, etc. [1,2,3]. Hydrogels with basic groups such as amine or acidic groups such as carboxylic acid are called polyelectrolyte gels [7,8]. The most significant property of these gels is their high swelling degree in the aqueous media. This high swelling ratio is caused by the ions of the basic or acidic groups in the molecular structures of the polyelectrolyte gels. These anions or cations formed from basic or acid groups on the polymer chains create a repulsive force between them and so expansion of network and swelling of gels take place [9]. It was decided to test the macroporous nanocomposite hydrogel as an amoxicillin carrier in drug delivery system due to the hydrogels excellent swelling properties
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