A new method for polybenzoxazine synthesis was developed and carried out throughout this work. Bisphenol-A, hexamethylenediamine, and paraformaldehyde were reacted through Mannich condensation reaction forming polybenzoxazine precursors. The reaction was followed by Gel Permeation Chromatography (GPC) as a molecular weight determination method in order to decide the end of reaction. The synthesized product, polybenzoxazine precursors, was polymerized thermally. Polybenzoxazine precursors were also characterized by using spectroscopic methods, 1H-NMR and FTIR, giving an approximation to structural determinations. Thermal characterization of precursors and polybenzoxazine showed that the materials had two exotherms at around 220&ordm / C and 260&ordm / C. The first exothermic peak was an indication of polymerization and preliminary crosslinking reactions while the second peak was due to the final polymerization of polybenzoxazine precursors. These precursors showed no significant structural change in isothermal period of 20 minutes at 200, 220, 225, 235&ordm / C. Mechanical tests were performed on the polybenzoxazine films. The films cured at 180&ordm / C possessed a tensile strength at break 21.04 (&plusmn / 3.56) MPa and an average elongation of 2.7 (&plusmn / 0.93) %. Young&rsquo / s modulus was calculated as 0.93 (&plusmn / 0.05) GPa for polybenzoxazine films.

Synthesis of a polymer with benzoxazine units in the main chain backbone by a trifunctional phenol, a difunctional amine, and paraformaldehyde was achieved. Thermal, mechanical and spectroscopic characterization and the viscosity properties of the synthesized polymer were studied. In the first step of this study, a fast and feasible method for the synthesis of the benzoxazine precursors was developed since some methods mentioned in the literature about the synthesis of the benzoxazine derivatives last long time. The second step was to polymerize the benzoxazine precursors thermally. The curing of benzoxazine precursors was done via ring opening polymerization at 150 oC and a final polymerization was observed at about 250 oC. 1H NMR, 13C NMR and FT-IR spectroscopies revealed the characteristic peaks for the formation of benzoxazine ring. Among them, 13C NMR gave important clue on the formation of the benzoxazine. The thermal characterization of the benzoxazine precursors and the polymers indicated that the ring opening polymerization of these precursors started at around 110 oC and a final polymerization was about at 230 oC. Differential Scanning Calorimetry thermograms of the polybenzoxazine indicated a secondary transition at around 270 oC. An onset decomposition of the benzoxazine oligomers started around 100 oC in Thermal Gravimetric Analysis thermograms performed under N2 atmosphere and two major maximum weight losses were observed at 273 oC and 439 oC. However, polybenzoxazine showed a starting degradation at about 260 oC and the maximum weight loss temperatures were seen at 296 oC and 465 oC. Viscosity variation of the reaction mixture was studied by Ubbelohde Viscometer at 30 oC. Viscosity results indicated that the increase in the intrinsic viscosity of the reaction mixture till 50th minute and followed by a decrease due to possible branching and the intra-crosslinking of the benzoxazine oligomers. Mechanical properties of the polymer films, prepared by compression molding at 180 0C, were investigated. Test results showed that low tensile strength whereas comparatively high elongation.

Hydrophilic poly(2-hydroxyethyl methacrylate), PHEMA, and hydrophobic poly(dimethyl siloxane), PDMS, segments containing copolymers have been widely used as a biomaterial. These amphiphilic copolymers also used as an emulsifying agent in polymer solutions and compatibilizer in polymer blends. In this case, solution polymerizations of HEMA by radiation, ATRP and RAFT methods were studied. The thermal degradation mechanism of PHEMA, which was prepared in aqueous solution by gamma radiation technique, was studied in detail. The DSC, TGA and Mass Spectroscopy analyses revealed that the degradation is linkage and depolymerization with a combination of monomer fragmentation. The ATRP of HEMA was performed with ethyl-2-bromoisobutyrate (EBriB) initiator and CuCl/bipyridine catalyst in MEK/1-propanol solvent mixture. Cu(II) complexes and PHEMA obtained via ATRP were characterized by UV-vis, FTIR and 1H-NMR analysis. The RAFT polymerization of HEMA with different [RAFT]/[AIBN] ratios were also investigated in three solvents (methyl ethylketone, ethyl acetate and toluene). The controlled polymerization of HEMA with the ratio of [RAFT]/ [AIBN]=18 at 80 oC in MEK and ethyl acetate, shows the first-order kinetic up to the nearly 40 % conversion Macroazoinitiator PDMS-MAI was synthesized from bifunctional PDMS and then copolymerized with MMA, EMA, HEMA and TMS-HEMA monomers Different characterization methods such as FTIR, 1H-NMR, solid state NMR, GPC, XPS, SEM, DSC, etc. have been used for the characterization of block copolymers. P(DMS-b-TMSHEMA) was converted to the P(DMS-b-HEMA) block copolymer by deprotection of TMS groups. The phase separated morphology was observed for the P(DMS-b-HEMA) copolymer, which was different from P(DMS-b-MMA) and P(DMS-b-EMA) copolymers.

In the first part of this dissertation, glass fiber reinforced/unreinforced polyamide 6 (PA6) and polyamide 66 (PA66) were compounded with three different flame retardants, which were melamine cyanurate, red phosphorus and brominated epoxy with antimony trioxide, by using an industrial scale twin screw extruder. Then, to investigate flame retardancy of these specimens, UL-94, Limiting Oxygen Index (LOI) and Mass Loss Cone Calorimeter (MLC) tests were carried out. In addition to flammability tests, thermogravimetric analysis (TGA) and tensile testing were performed. Results of the tensile tests were evaluated by relating them with fiber length distributions and fracture surface morphologies under scanning electron microscope (SEM). Incorporation of melamine cyanurate (MCA) to PA6 led to some increase in LOI value and minor reductions in Peak Heat Release Rate (PHRR) value. However, it failed to improve UL-94 rating. Moreover, poor compatibility of MCA with PA6 matrix caused significant reductions in tensile strength. Brominated epoxy in combination with antimony trioxide (Br/Sb) was compounded with both glass fiber reinforced PA6 and PA66. Br/Sb synergism was found to impart excellent flammability reductions in LOI value and UL-94 as V-0 rating. Effectiveness of Br/Sb flame retardant was also proven by the MLC measurements, which showed excessive reductions in PHRR and Total Heat Evolved (THE) values. On the other hand, Br/Sb shifted the degradation temperature 100&deg / C lower and decreased the tensile strength value, due to poor fiber-matrix adhesion and decreased fiber lengths. Red phosphorus (RP), when introduced to glass fiber reinforced PA66 induced V-0 rating in UL-94 together with significant increase in LOI value, and major decrease in PHRR. Degradation temperature was 20&deg / C lower while mechanical properties were kept at acceptable values compared to neat glass fiber reinforced PA66. In the second part of this dissertation, to investigate synergistic flame retardancy of nanoclays / glass fiber reinforced PA6 was compounded by certain nanoclay and an organo-phosphorus flame retardant (OP), which contains aluminum phosphinate, melamine polyphosphate and zinc borate, in a laboratory scale twin screw extruder. Exfoliated clay structure of the nanocomposites was assessed by X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM), while thermal stability and combustion behaviors were evaluated by TGA, LOI, UL-94 and MLC. Replacement of a certain fraction of the flame retardant with nanoclay was found to significantly reduce PHRR and THE values, and delay the ignition. Moreover, remarkable improvements were obtained in LOI values along with maintained UL-94 ratings. Residue characterization by ATR-FTIR and SEM ascribed the enhanced flame retardancy of nanocomposite specimens to the formation of a glassy boron-aluminum phosphate barrier reinforced by clay layers at the nanoscale.

Polymeric electrochromic materials that has as one of the three complementary colors (red, green, and blue) in the neutral form and become transparent via oxidation (or reduction), has a crucial importance towards use of these materials in electrochromic devices and displays. To reflect red or blue color in neutral state, the materials have to absorb at only one dominant wavelength. On the contrary, to have a green color, there should exist at least two simultaneous absorption bands in the red and blue regions of the visible spectrum where these bands should be controlled with the same applied potential. The transmissivity in the oxidized state is significantly important in addition to the neutral state color of the polymer. The optical contrast between the states is the decisive point for use of these materials for many electrochromic applications, especially as smart windows and displays. Hence, the material should possess two absorption bands with definite maximum points, and upon oxidation these bands should simultaneously vanish to have a transmissive state. A donor&ndash / acceptor approach can be utilized to solve this puzzle. It has been shown that insertion of alternating donor&ndash / acceptor units on the polymer backbone leads to a significant decrease in band gap due to the increased double bond character in the structure. In this study novel donor-acceptor type polymers were synthesized, and electrochromic properties were investigated in detail. PBDT is the first green electrochromic material which has a highly transmissive sky blue oxidized state. PDETQ was shown to be one of the few examples of neutral state green polymeric materials in literature. PDEQ has a bluish green color in the neutral state and a highly transmissive light blue oxidized state.

In the first part of this study, 4-(2,5-di-2-thiophen-2-yl-pyrrol-1-yl)-phthalonitrile (SNS-PN) was synthesized by utilizing 1,4-di(2-thienyl)-1,4- butadione (SOOS) and 4-aminophthalonitrile via Knorr-Paal Reaction. Nuclear magnetic resonance (1H NMR and 13C NMR) and fourier transform infrared (FTIR) spectroscopies were utilized for the characterization of this compound. SNS-PN monomer was then electrochemically polymerized in acetonitrile/0.2 M LiClO4 solvent/electrolyte couple. Characterizations of the resulting polymer P(SNS-PN) were carried out by cyclic voltammetry (CV), UV&ndash / vis and FTIR spectroscopic techniques. Spectroelectrochemical studies revealed that P(SNS-PN) has an electronic band gap of 2.5 eV and exhibits electrochromic behaviour. The switching ability of polymer was also monitored. It was also found that P(SNS-PN) was fluorescent and its fluorescence intensity enhanced in the presence of cations. In the second part, novel tetrakis (4-(2,5-di-2-thiophen-2-yl-pyrrol-1-yl)) substituted metal-free (H2Pc-SNS), zinc (ZnPc-SNS) and nickel phthalocyanine (NiPc-SNS) complexes were synthesized and characterized by elemental analysis, FTIR and UV-Vis spectroscopies. The solution redox properties of these complexes were also studied by using CV and differential pulse voltammetry. All of the complexes showed two reversible reduction peaks having ligand-based character and one irreversible oxidation peak. Also, the electrochemical polymerization of these complexes was performed in dichloromethane/tetrabutylammonium perchlorate solvent/electrolyte couple. Resulting polymer films were characterized by UV&ndash / vis and FTIR spectroscopic techniques and their electrochemical behaviors were investigated utilizing CV. In-situ spectroelectrochemical investigations revealed that all the polymer films could be reversibly cycled and exhibit electrochromic behavior. Furthermore, the band gap of P(H2Pc-SNS), P(ZnPc-SNS) and P(NiPc-SNS) were calculated as 2.38 eV, 2.25 eV and 2.69 eV, respectively. Moreover, the fluorescence property of the P(ZnPc-SNS) was investigated in dimethyl sulfoxide and toluene.

ABSTRACT PHOTO-OXIDATIVE DEGRADATION OF ABS COPOLYMER G&uuml / zel, Aylin M.S., Department of Polymer Science and Technology Supervisor: Prof. Dr. Teoman Tin&ccedil / er Co-Supervisor: Prof. Dr. Cevdet Kaynak September 2009, 55 pages Acrylonitrile-butadiene-styrene (ABS) polymer is one of the most popular copolymer having an elastomeric butadiene phase dispersed in rigid amorphous styrene and semi-crystalline acrylonitrile. Due to double bonds in the polybutadiene phase, ABS copolymers are very sensitive to photo-oxidative degradation. Photo-oxidation of butadiene rubber phase results in the formation of chromorphores and these chromorphores act as initiators in photo-oxidative degradation and after a while ABS starts yellowing. In this work, the relationship between the UV light and the yellowing of ABS samples was also investigated with respect to time. In this study, pure, light stabilized and commercial ABS samples were aged under UV light. As the UV light intensity increased from 800 to 2800 &amp / #61549 / W/cm2, yellowing of the samples were increased for pure ABS. This increase in yellowing of the samples was about 27 times higher compared to lower energy. In this study, UV stabilizers IRGANOX 1076 (sterically hindered phenolic antioxidant), IRGAFOS 168 (hydrolycally stable phosphite stabilizer) and TINUVIN P (hydroxyphenol benzotriazole) were used alone or in combination with each other. Pure ABS samples, commercial ABS samples and UV stabilized ABS samples were aged under the same UV light. UV aging degradation was followed by measuring the yellowness of the samples at certain time intervals. Yellowness of the samples was followed by using Coloreye XTH Spectrometer. Degradation in ABS, however, was followed by using FTIR with an increase in the peak area of carbonyl groups in the ABS matrix. Both color analysis and the FTIR analysis showed that combination of the IRGANOX 1076 and IRGAFOS 168 stabilizers gave the best stabilization. This revealed that combination of phenol and phosphate containing stabilizer is the most useful combination to prevent photo-oxidative degradation of ABS copolymer. Additionally, vegetable oil was applied to the surface of a new set of ABS samples and these samples were aged for 700 h. Yellowing tendency of these samples was compared with the yellowing tendency of ABS samples that are directly aged for 500 h. It was clearly observed that samples with oil smeared had more resistance to UV radiation with respect to others. This shows that oil acts protective layer to the UV light and oxygen and slow down the photo-oxidative degradation. Lastly some commercial ABS samples were compared to each other with respect to their yellowing tendency. Commercial ABS samples coded as K, L, A, B, C and D were aged under UV light at about 500 h. Sample A showed the best resistance against the yellowing among the other commercial ABS samples.

N-vinyl-2-pyrrolidone, NVP, was polymerized by &amp / #56256 / &amp / #56394 / -radiation in the presence of atmospheric oxygen and under vacuum at different periods. Polymerization also conducted by using chemical initiator, &amp / #56256 / &amp / #56466 / -Azoisobutyronitrile, AIBN, in bulk at different temperatures and times. The activation energy for polymerization was found from Arrhenius plot as 31,8 kJ/mol. By using the Fox-Flory equation T&amp / #56256 / &amp / #56394 / and k values calculated for each polymerization methods. The polymer obtained was white gel type. The different types of polymer obtained were investigated by FT-IR, 1H-NMR and 13C-NMR, DSC, TGA and viscosity measurement methods. According to the FT-IR and NMR results, the polymerizations proceeded via vinyl group. As expected, solution viscosity measurements and DSC results showed that the glass transition temperature of polymer increases with increasing molecular weight.

Synthesis of new electroactive monomers are highly desired since these compounds can be utilized as active layers in many device applications such as ECDs, LEDs and solar cells. Pyrrole and selenophene bearing polymers were also proven to be excellent candidates as electrochromic materials. Benzothiodiazole can be coupled to to pyrrole and selenophene yield materials that can be polymerized to give donor acceptor type polymers. These donor-acceptor type materials / Poly(4,7-di(1H-pyrrol-2-yl)benzo[c][1,2,5]thiadiazole P(PYBTPY) and poly(4,7-di(selenophen-2-yl)benzo[c][1,2,5]thiadiazole P(SEBTSE) were synthesized via bromination, stannylation and Stille coupling reactions. Electrochemical and electrochromic properties of the polymers were examined in detail.

Acrylonitrile based engineering random copolymers were prepared via one step emulsion polymerization using ammonium persulfate (initiator), 1-dodecanthiol (chain transfer agent) and DOWFAX 8390 (surfactant) in the presence of water at approximately 65 0C. Three copolymer compositions were studied for novel polyacrylonitrile, (PAN)-polyhydroxyethyl acrylate (PHEA), PAN-polybutyl acrylate (PBA), novel PAN-polyt-butyl acrylate (PtBA), PAN-polyethyl acrylate (PEA) and PAN-polymethyl acrylate (PMA) with acrylate content varying from 8, 12 and 16 molar percent. Infrared spectroscopy, proton and carbon NMR were successfully utilized to confirm the chemical structure of copolymers. In order to determine the comonomer compositions in the copolymer structure, proton nuclear magnetic resonance, 1H NMR studies were carried out. Thermal (TGA, DSC) and mechanical properties of homo and copolymers were also investigated. Intrinsic viscosity (IV) measurements in dimethyl formamide (DMF) solution revealed that the molecular weight of the copolymers were quite enough to form ductile films. In this study, hydrogels and their copolymers of acrylonitrile (PAN-PHEA) were also studied. Some properties of the free standing copolymer films such as / swelling behaviors and densities were evaluated. It was also demonstrated that the nanocomposites of these copolymers could be utilized in filtration technology. Hence, novel PAN(88)-co-PMA(12) and polyaniline (PANI) nanocomposites were prepared at various PANI loadings to remove toxic chromium(VI) solution from water. Chemical structure, swelling and fracture morphology of the nanocomposites membranes were studied. It was observed that PANI had a great impact on the chromium removal. Permeate flux and rejection of chromium(VI) were demonstrated for various pHs and chromium(VI) concentrations. Finally, influences of comonomer composition on the thermal properties of the copolymers were investigated to input their structure property relation.