Gokhan Temel

Modification of multiwall carbon nanotube by thiol-ene click chemistry

AbstractnThiol-ene click chemistry was used for the preparation of polystyrene grafted multiwall carbon nanotubes (MWCNTs) via the thermal initiation method. The thiol end-functional PSt (PSt-SH) was prepared by the nucleophilic substitution reaction of the bromide end groups of PSt obtained by atom transfer radical polymerization. PSt-SH grafted to the surface of the MWCNTs by thiol-ene click chemistry via the thermal initiation method.n

“Mono” and “bifunctional” aromatic esterificated benzophenone photoinitiators for free radical polymerization

Aromatic esterificated benzophenone derivatives, benzoic acid 4-benzoyl-phenyl ester (BPBz) and bis-benzoic acid 4-benzoyl-phenyl ester (BisBPBz) were simply synthesized and characterized. The triplet states of the photoinitiators were determined by laser flash photolysis and phosphorescence spectroscopy. The photodecomposition of the initiators was performed by UV light; the increase in the absorption spectra was attributed to the decreasing number of ester groups which led to an increase in ketone groups according to the Photo-Fries rearrangement of aromatic esters. The photoinitiation capabilities for methyl methacrylate (MMA) polymerizations were investigated under air and nitrogen atmospheres. Ester-functional benzophenone photoinitiators were found to be more effective than benzophenone (BP) in the presence of a co-initiator for photoinduced free radical polymerization of MMA. The kinetics of photopolymerization for different formulations which consist of multifunctional acrylates was also studied using the Real-Time Fourier Transform infrared spectroscopy (RT-FTIR) method. The film properties of these formulations were investigated after curing of films by Mini-UV-Cure equipment.

Preparation of photodegradable polyacrylamide hydrogels via micellar copolymerization and determination of their phototunable elasticity and swelling behaviors

Polyacrylamide (PAAm) hydrogels were prepared by micellar copolymerization methodology in the presence of acrylamide and photo-decomposable hydrophobic crosslinker (diacrylated Irgacure-2959). After the synthesis of hydrophobically functionalized hydrogels via free radical copolymerization, gel samples were exposed to UV irradiation for different time intervals between 0 and 17 hours in aqueous medium. According to the results of swelling and compression tests, the physical properties of the hydrogels were altered by UV exposure time. The swelling degree of the hydrogels increased gradually with the irradiation time. Moreover, the 17 h irradiated hydrogel sample was entirely decomposed at the end of the swelling test. According to Scanning Electron Microscopy images, UV irradiated hydrogel samples exhibited an apparent degradation behavior.