Preparation and characterization of acrylic acid and 2-hydroxyethyl methacrylate grafted poly(ethersulfone) and poly(ethersulfone)/graphene oxide nanocomposites and their use as coating material

In this thesis, studies on polymer resins which are binders used as paint component in the coating industry, are planned and experimental studies are carried out within the scope of the preparation and properties of polymer/graphene-based nanocomposite coatings. During the preparation of nanocomposites; poly(ethersulfone) (PES) polymer was used as the matrix, and graphenoxide (GO) nanopowder, which could be included in the polymer matrix more strongly due to the functional groups, was used as the reinforcement material. Due to the hydrophilic nature of GO; PES/GO nanocomposite materials were prepared by adding GO to the PES matrix to increase its hydrophilic structure. In order to form nanocomposites without decomposing in polymer structures, the preparation of nanocomposites was made by using the solution-to-melt method together with ultrasonication and impregnation methods. In the ultrasonication method, an ultrasonicator was used by selecting the appropriate time and mixing speed range. In the next study, surface modifications of films and nanocomposite materials were provided by UV-initiated graft polymerization studies. Firstly, after the PES polymer was dissolved in dichloromethane (DCM), its film was formed and the optimum grafting parameters were determined by performing acrylic acid (PAAc) and 2-hydroxyethylmethacrylate (HEMA) grafting studies on the film at different monomer composition, irradiation time and irradiation distances, respectively. PES/dichloromethane (DCM/GO) and PES/N methyl-2-pyrrolidone (NMP/GO) nanocomposites were formed, but since homogeneous films could not be formed from PES/DCM/GO dispersion solution, homogeneous films obtained from PES/NMP/GO dispersion solutions and grafting studies were carried out two different ways; films and dispersions. Since PES polymer is sensitive to UV light in the wavelength range of 280-400 nm, PES itself acted as a photoinitiator without the need for another photoinitiator. Spectroscopic characterizations of all the structures obtained were performed with Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, X-Ray Diffraction Spectroscopy (XRD), X-Ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM). Gravimetric percent grafting efficiencies were calculated after grafting, hydrophilic/hydrophobic characterizations of the surfaces as a result of surface modification were determined by measuring the contact angle. Measurements related to surface morphology were made with SEM and digital microscope using Confomap software, surface roughness and contact angle results were evaluated together. With AAc and HEMA, GO increased the hydrophilic character of PES. We determined that due to the hydrophilic nature of AAc and HEMA monomers, the contact angle results decreased in the structures formed as a result of graft polymerization, and the hydrophilicity increased in the AAc and HEMA grafted structures in the presence and absence of GO. In addition, we see that the results of the contact angle as a result of the UV-initiated grafting made from the dispersion decrease more in the structures obtained by the grafting on the film surface and the surface hydrophilicity increases further. This result shows that grafting in dispersion medium is more efficient than grafting on film surfaces. Due to the hydrophilic nature of AAc and HEMA monomers, the contact angle values of the structures formed as a result of graft polymerization decreased, and the hydrophilicity of AAc and HEMA grafted structures increased in the presence and absence of GO. In addition, the results of the contact angle as a result of the grafting done in the dispersion medium and initiated with UV decreased more and the surface hydrophilicity was further increased in the structures obtained by grafting on the film surface. This is due to the fact that the grafting made in the dispersion medium is carried out with a higher efficiency than the grafting made on the film surfaces. Spectroscopic, thermal and mechanical characterizations of grafted and non-grafted structures in the presence and absence of GO were performed and the results were compared.