The aim of this work was to prepare and characterize the novel antibacterial nanocomposites based on chitosan, grafted acrylic acid and silver nanoparticles (AgNPs). Chitosan has been functionalised by chemical reaction with acrylic acid, and then mixed with silver nanoparticles (AgNPs). AgNPs have been obtained formerly by chemical reduction of silver nitrate in the presence of mercaptosuccinic acid as a nanoparticles stabilizer. Structure and properties of obtained nanocomposite have been characterised by UV-vis, FTIR and 13C-NMR spectroscopy. The morphology of silver chitosang-acrylic acid nanocomposite has been studied by electron microscopy (SEM/EDX and HR-TEM). Thermal stability has been investigated by thermogravimetric analysis. The grafted chitosan contained 70.9 % wt acrylic acid, as determined by gravimetric method. It was found that modified chitosan forms water-insoluble gel with lower thermal resistance than pure chitosan. However, the difference between thermal properties of grafted chitosan and its nanocomposite with AgNPs is negligible. The grafting reaction mechanism has been discussed in detail on the basis of the obtained results and current literature data.

Poly(acrylic acid) and N-phenylbenzothioamide have been synthesized under laboratory conditions. The purity of products has been checked by FTIR and NMR spectroscopy. The obtained N-phenylbenzothioamide has been used for modification of poly(acrylic acid) properties. The prepared blend of PAA contained small amout of dopant (1-5 wt %). Thermal and photochemical stability of obtained specimens were investigated using UV-Vis spectroscopy and thermogravimetric analysis. Crosslinking yield was estimated by extraction of insoluble gel formed. It was found that Nphenylbenzothioamide stabilizes poly(acrylic acid) during UV-irradiation which is explained by efficient crosslinking reaction.

Poly(acrylic acid), PAA, has been mixed in solution with silver nanoparticles, obtained by chemical reduction of silver nitrate. Two different sulfurcontaining organic compounds have been used as stabilizers of Ag nanoparticles: mercaptosuccinic acid (MSA) and 3-mercaptopropionic acid (MPA). The formation of Ag nanoparticles has been monitored by UV-Vis spectroscopy. The morphology and composition of obtained nanomaterials has been studied by electron microscopy techniques (SEM/EDX and HR-TEM). Nanomechanical properties of nanocomposites (adhesion and nanohardness) have been investigated by Atomic Force Microscopy (AFM). Thermal stability has been determined using thermogravimetric analysis. The exposure of specimens to UV radiation allowed to observe the changes in the nanoparticle structure and to estimate nanocomposite photostability. MSA has proved to be a better stabilizer of Ag nanoparticles immediately after the synthesis, when MPA provides better storage stability. MPA has allowed for the creation of nanoparticles using mixed reduction (chemical/photochemical) of AgNO 3 . It has been found that the nanocomposite materials are stable for 12 months of storage in solution and in solid form.

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