Syntheses of biodegradable PLLA homopolymers and PLLA-mPEG diblock copolymers for the formation of thermo-sensitive gels were performed. The sol-gel transition temperature of the matrix was adjusted by altering the length of each PEG and LA component. PLLA-mPEG biocompatible copolymers, having appropriate length of each block component, showed sols at around 42-45 oC, suitable for the injection, then a gel with subsequent rapid cooling to body temperature. Topotecan and camptothecin were selected as anti-cancer drugs. Both drugs can easily hydrolyze at physiological conditions (pH=7.4). This causes the loss of its activity, and it turns into inactive toxic carboxylate form from active lactone state. To keep those anti cancer drugs in the lactone form, they were efficiently loaded into PLLA-mPEG gels in different loading ratios. Their stability in gel was fully examined with HPLC and fluorescence spectroscopy. It was found that both drugs were highly stable and in active form in the prepared gels (&gt / 95 %). Then, both release profile of drugs at different loading ratios showed prolonged release over weeks. Mechanistic studies on the stabilization of CPT anti cancer drug with PLLA-mPEG gels were carried out using ATR-FTIR, confocal and optic microscopes. The cytotoxic efficacy of TPT in the PLLA-mPEG platform (PLLA-mPEG-TPT) was evaluated on LLC-1 and 4T1 cancer cell lines by MTT assay. In vivo, the administration of PLLA-mPEG-TPT to the mice bearing breast tumours established with 4T1 cells resulted in a significant reduction in tumour size and better survival percentages. Additionally, stabilization of CPT and TPT with gels may find another application on solid tumors in brain via local injection. A novel conducting polymer was successfully synthesized via electropolymerization of 1-(1H-pyrrol-1-yl)-2,5-di(thiophen-2-yl)-1H-pyrrole. The electrochemical and electro-optical properties of the corresponding polymer, which was the first example of polymer containing 1,1&rsquo / -bipyrrole units, were elaborated using electroanalytical and spectroscopic techniques. Cyclic voltammograms and electrooptical studies showed that the polymer has a stable and well-defined reversible redox process as well as electrochromic behavior. The processable polymer film also possessed a yellowish orange light emitter property.

Due to brittleness of polystyrene, PS, its usage area is restricted. To solve this problem and expand the usage area of PS, it can be blended and impact modified with an elastomeric material. In this study, the decrease in the modulus and tensile strength imparted by impact modification was overcome by reinforcing this mixture by incorporating organoclays and producing nanocomposites. This study consists of two parts. In the first part of this study three different types of aliphatic elastomeric materials and three different types of organoclays were used and their effects on the morphology, mechanical, thermal, and rheological properties of PS were investigated. Lotader AX8900, Lotader AX8840 and Lotader 2210 were chosen as the aliphatic elastomeric compatibilizers / and Cloisite

In this thesis there were two main purposes, the first one being to investigate effects of zinc borate (ZB) on the flammability behavior of ABS when used with and without a traditional brominated flame retardant (BFR) / antimony trioxide (AO) system. The second purpose was to investigate contribution of nanoclays (NC) to the flame retardancy performance of the same traditional BFR compound with various combinations of AO and ZB again in ABS matrix. For these purposes, materials were melt compounded by using a laboratory scale twin-screw extruder, while specimens were produced by injection or compression molding. Flame retardancy of the specimens were investigated by Mass Loss Cone Calorimeter (MLC), Limiting Oxygen Index (LOI) measurements and UL-94 vertical burning tests. Other characterization techniques required in this thesis were / X-ray diffraction analysis, scanning and transmission electron microscopy, thermogravimetric analysis and tensile tests. Studies for the first purpose indicated that almost all flame retardancy parameters were preserved when antimony trioxide were replaced with zinc borate as much as in the ratio of 1:3. Residue analyses revealed that predominant flame retardancy mechanism of traditional system was gas phase action, while zinc borate contributes especially in the condensed phase action by forming thicker and stronger char layer. Investigations for the second purpose basically concluded that use of nanoclays improved all flame retardancy parameters significantly. Residue analyses pointed out that nanoclays especially contribute to the formation of stronger and carbonaceoussilicate char acting as a barrier to heat and flammable gases and retarding volatilization via tortuous pathway. As an additional third purpose in this thesis, usability of three boron compounds (zinc borate ZB, boric acid BA, boron oxide BO) with two traditional flame retardants (organic phosphinate OP and melamine cyanurate MC) in neat PET and recycled PET were also examined leading to some promising results in MLC parameters.

The interest towards organic semi-conductors increased due to their tunable band gaps, redox properties, processability and low cost in the field of conducting polymers. Electrochromic materials have the ability to change color by altering their redox state. In the context of low cost flexible display device technology, requirements can be fulfilled with accessible multi-colored electrochromic polymers. In this study, we report the chemical synthesis and electrochromic properties of two spray processable, ambipolar, fluorescent and multi-color to transmissive electrochromic polymers. The electrochromic properties of these polymers were examined by cyclic voltammetry, spectroelectrochemistry, kinetic studies. Polymers, PTBTPh and PTBTTh, have multi-colored oxidation states and easily accessible ndoped states, which allowed us to achieve transmissive films in a low working potential. Electrochemical and spectral results showed that both polymers are potential materials for electrochromic display devices.

In this study, a novel series of conjugated monomers containing furan and fluorene units / 2,7-di(furan-2-yl)-9H-fluoren-9-one (FOF), 2-(2-(furan-2-yl)-9H-fluoren-7-yl)furan (FFF), and 2-(2-(furan-2-yl)-9,9-dihexyl-9H-fluoren-7-yl)furan (FHF) were synthesized and their electrochemical polymerization were achieved via potential cycling. Optical and electrochemical properties of the polymers, poly(2,7-di(furan-2-yl)-9H-fluoren-9-one) (PFOF), poly(2-(2-(furan-2-yl)-9H-fluoren-7-yl)furan (PFFF) and poly(2-(2-(furan-2-yl)-9,9-dihexyl-9H-fluoren-7-yl)furan) (PFHF) were investigated and it was found that polymer films exhibit reversible redox behavior (Epox = 1.083 V for PFOF, Epox= 0.915 V for PFFF and Epox= 0.985 V for PFHF) accompanied with a reversible electrochromic behavior, orange to green for PFOF, yellow to dark blue for PFFF and orange to green for PFHF during oxidation. Their band gap values (Eg) were found to be 2.32, 2.49 and 2.61 eV for PFOF, PFFF and PFHF, respectively.

During last decade, polyurethanes (PUs) which are able to degrade into harmless molecules upon implantation have received a significant level of attention as a biomaterial in tissue engineering applications. Many studies are focused especially on development of PUs based on amino acid derivatives / however, there are only few applications of amino acid based PUs in tissue engineering. In this study, a biocompatible and biodegradable thermoplastic poly(ester-urethane) (PEU) based on L-lysine diisocyanate (LDI) and polycaprolactone diol (PCL) was synthesized and used for the preparation of two dimensional (2D) films and three dimensional (3D) scaffolds. The resulting polymer was casted as 2D films for full characterization purpose and it was found that it is highly elastic with modulus of elasticity ~12 MPa. Surfaces of 2Ds were modified via micropatterning and fibrinogen coating to check the material-cell interaction. The 3D scaffolds were obtained by salt leaching and rapid prototyping (bioplotting) techniques. The 3D scaffolds had various pore size and porosity with different mechanical strength. The bioplotted scaffolds had uniform pore size of ~450 &micro / m and exhibited higher compressive modulus (~4.7 MPa) compared to those obtained by salt leaching (~147 kPa). Salt leached 3D scaffolds had inhomogenous pore size distribution in the range of 5 &micro / m - 350 &micro / m and demonstrated greatest degradation profile compared to 2D films and 3D bioplotted samples under enzymatic condition. Rat bone marrow stem cells (BMSCs) were used to investigate the biocompatibility of the polymer and suitability of fabricated scaffolds for osteogenesis. Presence of micropatterns on 2D matrices did not show any influence on osteoblastic function, but presence of fibrinogen enhanced cell attachment and proliferation. All of the fabricated 3D PEU matrices supported proliferation, osteoblastic differentiation and extracellular matrix (ECM) deposition with highest osteoblastic activity on bioplotted scaffolds which confirmed by von Kossa staining and EDX analysis. The results indicated that the synthesized PEU based scaffolds were able to induce osteoblastic differentiation and mineralization of BMSC and therefore these scaffolds can be good candidates to be used in bone tissue engineering

Controlled drug delivery systems are becoming increasingly interesting with the contribution of nanotechnology. In the case of transdermal applications the greatest limitation is the highly impermeable outermost layer of the skin, the stratum corneum. One promising method of controlled transdermal drug delivery of the skin therapeutics is the use of nanoparticles as carriers. Encapsulation of the drug, as opposed to classical topical application of creams or emulsions, allows the drug to diffuse into hair follicles where drug release can occur in the deeper layers of the skin. The aim of this study was to develop micro and nano sized carriers as drug delivery systems to achieve treatment for skin conditions like psoriasis, aging or UV damage, caused by radiation or health problems. Two different types of bioactive agents, retinyl palmitate (RP) and Dead Sea Water (DSW), were used by encapsulating in poly(3-hydroxybutyrate-co-3-hydroxyvalerate) carriers. In some tests MgCl2 was used as a substitute for DSW when quantification was needed. Bioactive agent loaded nanospheres and nanocapsules were prepared with o/w and w/o/w methods in low micron (1.9 &micro / m), mid nano (426 nm) and nano (166 nm) sizes. Loading, encapsulation efficiency and release kinetics were studied. The encapsulation efficiency and loading values are low especially for the water soluble agents, DSW and MgCl2. It was observed that the capsules loaded with hydrophilic agents released their content in the first 24 h in aqueous media. The encapsulation efficiency and loading values for RP were higher because of the insolubility of the agent in water. In the in vitro studies carried out with L929 mouse fibroblast cells, the nano sized PHBV capsules were detected in the cytoplasm of the cells. Cell viability assay (MTT) for L929 cells showed a growth trend indicating that the particles were not cytotoxic and the values were close to the controls. Hemolytic activity was examined using human erythrocytes and micro/nanoparticles of PHBV were found to be non hemolytic. In vivo testing with BALB/c mice, nanocapsule penetration revealed that a small amount of nano sized particles penetrated the mice skin, despite the highly impermeable outer skin layer. As a result, PHBV micro/nanoparticles have a significant potential for use as topical drug delivery systems in the treatment of skin diseases.

Donor-acceptor-donor approach is one of the effective ways to synthesize low band gap polymers. The monomers that will be designed with respect to donor-acceptor-donor approach have low band gap achieved by the coupling of a strong donor with high HOMO level to a strong acceptor with low LUMO level. Thus, the new donor-acceptor material will have a reduced bandgap (Eg) relative to either of its parent components. Due to this point of view, in this study, new electroactive benzothiadiazole and 2,3-bis(4-(tert-butyl)phenyl)quinoxaline monomers substituted with different donor groups (3,4-ethylenedioxythiophene and thiophene) were synthesized to explain the effect of different donor groups on the electronic and optical properties of DAD type polymers. The characterizations of the monomers were performed by 1H and 13C NMR techniques. Electrochemical behavior of both monomers and polymers were studied by cyclic voltammetry. The electrochromic properties of the synthesized conducting polymers were investigated by several methods like spectroelectrochemistry, kinetic and colorimetry studies. The polymers have two different donor units may behave as a copolymer of the symmetric monomer having the same donor groups. Hence, the properties of copolymers were investigated with the co-monomers having either thiophene or 3,4-ethylenedioxythiophene as the donor group.

In the present study the effects of addition of organically functionalized boehmite nano-particles on the mechanical properties of epoxy polymers were analyzed. Nanosize platelets of boehmite powders were produced via a hydrothermal process from the raw material aluminum trihydroxide Al(OH)3 provided by a a chemical supplier, but which in future studies can be replaced by local resources of aluminum trihydroxide available in Seydisehir, Turkey. The ground aluminum trihydroxide particles were submitted to a two-step preliminary ageing procedure in different pH media. Particles were then converted to boehmite nanoparticles via hydrothermal ageing at high pressure and temperature. The product&lsquo / s chemical identity, size, structure and morphology were characterized with XRD, FT-IR, SEM and PSA analyses. By controlling the pH and the ageing time as parameters, hexagonal shaped nanoplatelets were obtained with dimensions ranging from 100 to 500 nm. Aiming at using these nanoparticles into surface coating polymers, the most favorable shape is the plate-like morphology, leading to adopting the last hydrothermal condition in the rest of the study. v The boehmite crystal surfaces are furnished with hydroxyls which can potentially be reacted with epoxy monomers of bisphenol A diglycidyl ether with the help of tin (II) chloride as catalyst through ring-opening reactions. The FT-IR and quantitative analyses indicated that this surface functionalization is possible under a temperature 80 oC and a weight ratio of 5:1 epoxy monomer to boehmite powder These novel inorganic/organic hybrid materials were then mixed with epoxy/hardener resin mixture to obtain nanocomposites. The properties of the composites were characterized accordingly with tensile, impact, micro hardness, micro-scratch tests, DMA analysis and observed with SEM analysis. A deterioration of the tensile strength from the neat polymer was observed, with a distinct trend between the functionalized and non-functionalized boehmite-epoxy polymers. The functionalized polymers showed a less deteriorative character. The tensile modulus instead showed a little improvement of (4%) in 5wt% loaded polymers. DMA analysis results revealed an improved glass transition temperature in the nanocomposites as well as in storage and loss modulus. As aimed in this work, the functionalized boehmite-epoxy polymers displayed a clear improvement in comparison to both non-functionalized and neat polymers in surface coating properties in hardness and scratch resistance.

The desirable properties of polyurethanes (PUs) such as mechanical flexibility associated with chemical versatility make these polymers attractive in the development of biomedical devices. In this study, various segmented polyurethanes were synthesized through polymerization reactions between polycaprolactone (PCL) diol or triol and excess hexamethylene diisocyanate (HDI) with varying NCO/OH ratios and the effect of composition on the properties of the resultant polyurethane films were examined. Initially, isocyanate terminated prepolymers were synthesized through one-shot polymerization, and then these prepolymers were cured by introducing crosslinkages into the structure and thus PUs were obtained. In order to enhance biocompatibility and hydrophilicity of the resulting polymers, heparin was added into the prepolymer before the curing process. The influence of excess HDI as a crosslinker on the degree of H-bond formation between hard-hard segments or hard-soft segments was examined by using Fourier transform infrared-Attenuated total reflectance spectroscopy (FTIR-ATR). Also the effects of HDI content on the chemical, physical and mechanical properties of the polyurethanes were examined with differential scanning calorimetry (DSC), X-Ray diffraction spectroscopy (XRD), dynamic mechanical analyzer (DMA), mechanical tester and goniometer. FTIR- ATR, DSC and DMA analyses showed that use of triol resulted in better network formation and homogenous distribution of hard segments within soft segment matrix. Incorporation of heparin into the polymer matrix produced more hydrophilic films (water contact angle reduced from 80 to 60). Polyurethanes from PCL and HDI in the absence of any solvent, initiator, catalyst or chain extender were successfully synthesized and this kind of synthesis enhanced biocompatibility and increased the potential of polymers for use in biomedical applications.