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In this study, novel hydrogels based on polyurethane/polyethylene glycol (PU/PEG) and their silver nanocomposites (PU/PEG/Ag x, x = 100, 200, 400, and 800) were developed using click chemistry and a green method. Mechanical analysis showed that introducing of silver nanoparticles (AgNPs) into hydrogels and increasing the content increased their mechanical properties dramatically. Tensile strength and elongation at break increased from 0.2 MPa and 105% for PU/PEG to 2.5 MPa and 210% for PU/PEG/Ag 800. Similarly, the compressive strength increased from 5 to 55 MPa. Investigation of the SEM images showed that the AgNPs were homogeneously dispersed throughout the hydrogel network, and through the incorporation of silver nanoparticles in hydrogels, the pore size of hydrogels decreased. Therefore, the swelling degree of hydrogels decreased by increasing the content of AgNPs. FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS) demonstrated that the interaction of network heteroatoms with AgNPs was responsible for stabilizing silver nanoparticles. The antibacterial properties of nanocomposites were evaluated against Pseudomonas aeruginosa and Staphylococcus aureus bacteria. These nanocomposites showed significant activities against S. aureus bacteria. In addition, the cell viability test showed that these nanocomposites had good biocompatibility (84% cells viable). Therefore, they could be favorable candidates for wound dressing applications.

methacrylate) (PMMA) copolymer, were synthesized and characterized. sPS has been synthesized by using half sandwich titanocene/methylaluminoxane catalyst in homogenous conditions. Then, a-phenyl chloroacetylation of sPS was accomplished in a heterogeneous process by using carbon disulfide as dispersing medium and a-phenyl chloroacetyl chloride and anhydrous aluminum chloride as acetylating agent and catalyst, respectively. The graft copolymer of sPS with aPS or PMMA were synthesized by atom transfer radical polymerization using a-phenyl chloroacethylated sPS as initiator and CuBr and bipyridine as catalyst. The structure of obtained copolymer was investigated by 1 H NMR, FTIR spectroscopy, and thermal behavior of copolymers was performed by differential scanning calorimetry analyses.

This paper describes a new method to prepare graft copolymers, such as polyethylene-g-polystyrene (PE-g-PS), with a relatively well-controlled reaction mechanism. The chemistry involves a transformation process from the metallocene copolymerization of ethylene and m,p-methylstyrene (m,p-MS) to nitroxide-mediated ''living'' free radical polymerization (LRFP) of styrene. The metallocene catalysis produces ethylene-co-m,p-methylstyrene (EMS) random copolymers. Next, 1-hydroxyl-2,2,6,6-tetramethylpiperidine (HO-TEMPO) was synthesized by the reduction of TEMPO with sodium ascorbate. The macroinitiator (EMS-TEMPO) was synthesized with the bromination reaction of EMS, and the following nucleofilic reaction with this functional nitroxyl compound. The resulting macroinitiator (EMS-TEMPO) for LRFP was then heated in the presence of styrene to form graft copolymer. DSC, 1 H-NMR, FTIR spectroscopy were employed to investigate the structure of the polymers. The results of Molau test showed that PE-g-PS could be a potential good compatilizer.Bisindenyl ethane zirconium dichloride was synthesized by modification of the literature methods. 24 A brief description of this method is as follows. Scheme 1. Copolymerization reaction of ethylene with m,p-methylstyrene and following bromination reaction.Scheme 2. Synthesis of macroinitiator EMS-TEMPO and polyethylene graft copolymer.