Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

Browse

Filters

2007 - 200932010 - 201912020 - 20241

Settings

Scopus Q: search.filters.scopusQuartile.N/ASubject: search.filters.subject.Biopolymers

Search Results

Now showing 1 - 5 of 5
  • Master Thesis
    Synthesis and Characterization of Polycaprolactone-Polyvalerolactone Copolymer and Its Use in Melt Electrowriting Applications
    (01. Izmir Institute of Technology, 2024) Dinçkal, Sanem; Yıldız, Ümit Hakan
    This thesis focuses on the synthesis and characterization of Poly(ε-caprolactone) (PCL) and its block copolymers, Poly(ε-caprolactone)-b-Poly(4-hydroxyvalerate) (PCL-b-P4HV) and Poly(ε-caprolactone)-b-Poly(δ-valerolactone) (PCL-b-PVL). These polymers were synthesized through ring-opening polymerization of various lactones (ε-caprolactone, γ-valerolactone, and δ-valerolactone) using biocatalysts such as citric acid, glycolic acid, salicylic acid, boric acid and acetic acid. Detailed analytical and thermoanalytical characterizations were performed. Differential Scanning Calorimetry (DSC) showed that most homopolymers and copolymers exhibited crystallization (Tc) and melting temperatures (Tm) varying between 5-25°C and 50-65°C respectively, confirming successful polymerization. DSC thermograms of block copolymers revealed that solvent choice for precipitation affected crystallinity and thermal properties, with a small second melting point observed due to different crystalline forms. Fourier Transform Infrared Spectroscopy-Attenuated Total Reflectance (FTIR-ATR) confirmed the homopolymerization of Poly(ε-caprolactone) using citric, glycolic, and salicylic acids. Mass spectrometry further revealed characteristic peaks corresponding to expected molecular weights and compositions of the copolymers. The presence of these peaks corroborated the formation of block copolymers with distinct blocks of PCL, P4HV, and PVL confirmed the molecular integrity of the synthesized block copolymers. This thesis provides a comprehensive analysis of the synthesis and characterization of block copolymers, offering insights into their structural properties and potential applications. The findings contribute to the understanding of the polymerization process and the properties of the resulting materials, which are significant for industrial and biomedical applications. The resultant copolymers were utilized in Melt Electrowriting process to provide tissue scaffold. Despite their brittleness, all copolymers were electrowritten without issues, indicating their potential interest in tissue engineering applications.
  • Master Thesis
    Synthesis and Raft Polymerization of Arginine Containing Monomer To Investigate the Cell Membrane Translocation
    (Izmir Institute of Technology, 2014) Uğur, Deniz; Bulmuş Zareie, Esma Volga
    In this study, a higly cationic biosynthetic polymer, poly(Arginine Methyl Ester Methacrylamide) (p(AMME)) has been designed as a potential component of intracellular delivery systems for biological macromolecular therapeutics such as nucleic acids. Accordingly, an arginine derivative monomer; Arginine Methyl Ester Methacrylamide (AMME) was synthesized by the reaction of an active ester monomer, pentafluorophenylmethacrylate (PFMA) and the L-arginine methyl ester hydrochloride (AME) in the presence of excess triethyl amine. AMME was then polymerized via both conventional free radical polymerization and reversible addition-fragmentation chain transfer (RAFT) polymerization. The polymers p(AMME) were characterized via nuclear magnetic resonance and gel permeation chromatography techniques. The conventional free radical polymerization experiments yielded polymers with uncontrolled molecular weights and wide molecular weight distribution, whereas RAFT polymerizations performed both in aqueous solution and organic solvent yielded polymers with controlled molecular weights and narrow molecular weight distributions. The RAFT polymerization kinetic experiments showed the RAFT-controlled character of AMME polymerization in the presence of 4-cyano-4-(ethylthiocarbonylthioylthio) sulfanylpentanoic acid (ECT) as a RAFT agent. The cytotoxicity of P(AMME) before and after aminolysis was determined via MTT assay using A549 human lung cancer cell line. P(AMME) before aminolysis of the RAFT end-group displayed dose-dependent toxicity after 24 hours incubation with cells. It was highly toxic to cells at 25 μM concentration, killing almost more than 60% of cells after 24 hours incubation. On the other hand, the aminolyzed polymer has no significant toxicity in the concentration range studied (upto 500 μM), which was comparable with octaarginine, a widely used transfection agent. In conclusion, well-defined arginine-polymers synthesized in this study show potential for further investigations as potential components of intracellular delivery systems for therapeutics.
  • Master Thesis
    Protection of the Marble Monument Surfaces by Using Biodegradaple Polymers
    (Izmir Institute of Technology, 2007) Ocak, Yılmaz; Sofuoğlu, Aysun
    The deterioration of historic buildings and monuments constructed by marble has been accelerated in the past century due to the effects of air pollution. The main pollutant Sulphur dioxide (SO2) reacts with marble composed primarily of calcite (CaCO3), the firs step of decay which called gypsum (CaSO4.2H2O) crust is formed and this process can be accelerated when the surfaces exposed to the rain.In this study, the possibilities of slowing down the SO2-marble reactions were investigated by coating the surface of marble with some bio-degradable polymers: zein, chitosan, polyhydroxybutyrate (PHB) and polylactic acid (PLA) as protective agents.Uncoated control marbles and biodegradable polymer coated marbles were exposed at nearly 8 ppm SO2 concentration at 100 % relative humidity conditions in a reaction chamber for several days. The extent of reaction was determined by leaching sulphate from the marble surface into deionized water and measuring the total concentration of sulphate with ion chromatography (IC). Then, gypsum crust thickness, polymers % protection factor and average deposition velocity were calculated. Concurrently, the ratio and amount of calcium sulfite hemihydrate (CaSO3.H2O)and gypsum (CaSO4.2H2O) were determined by FT-IR analysis. The surface morphology of SO2 exposed marble to distinguished calcium sulfite hemihydrate and gypsum crystals were determined by Scanning Electron Microscope (SEM).The results of the study showed that SO2-calcite reaction increased in the use of zein, glycerol added zein and chitosan polymers on the surface of marble. While, PHB treated marble surfaces had 5 % increases in the protection factor. The low molecular weight PLA protection factor was 45 % after 85 days exposure. Similar results were observed when the high molecular weight of PLA used. The protection was extended to more than 90 days having 60 % protection factor.
  • Master Thesis
    Preparation and Characterization of Corn Zein Coated Polypropylene (pp) Films for Food Packaging Applications
    (Izmir Institute of Technology, 2007) Atik, İsa Doğan; Tıhmınlıoğlu, Funda
    The plasticized corn-zein coatings on polypropylene (PP) films as an alternative to multilayer packaging films consisting of non-degradable polymers were prepared to evaluate barrier, mechanical, thermal, surface and optical properties of the resulting coated film, as affected by coating formulation (solvent, corn-zein, plasticizer concentration, and plasticizer type). PP films coated with corn zein were obtained through a simple solvent casting method. Corn-zein with different amounts (5% and 15%) was dissolved in 70% and 95% aqueous ethanol solution at 50oC, respectively. Solutions of corn-zein plasticized by polyethylene glycol (PEG) and glycerol (GLY) with various levels (20% and 50%) were applied on corona-discharged-treated PP film. The resulting corn-zein coated PP films showed good appearance, flexibility and adhesion between the coating and the base film. The coated PP films showed a significant (P<0.05) increase in barrier (water and oxygen) properties and improvement in mechanical properties when coating formulation consisted of higher corn-zein content and lower amount of GLY as plasticizer. Furthermore, zein coating increased the service temperature range of the PP films, and promised good printability on the surface due to contact angle results. The statistical analysis defined that the key parameters of coating formulation that had major effect on the final properties of coated PP films as corn-zein concentration, plasticizer concentration, and plasticizer type while ethanol concentration was found to be as less effective parameter compared to others. In conclusion, corn zein coatings with appropriate formulation on PP films could have potential as an alternative to conventional synthetic coatings for food packaging applications.
  • Master Thesis
    Kinetics of Oil Dispersion in the Presence of Chitosan Based Biopolymers
    (Izmir Institute of Technology, 2009) Şen, Didem; Polat, Hürriyet
    This study was focused on the modification of chitosan to produce surface active biopolymers and their application as emulsifiers. Therefore N-acylation of chitosan was utilized. Characterization of the produced materials were achieved by the following ways; Ninhydrin assay, Elemental Analysis, Fourier Transform Infrared Spektroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), surface (or interfacial) tension and contact angle measurements. These characterizations provided information about the substitution degree, structure and the hydrophobic-hydrophilic properties of the produced surface active biopolymer. For example, the surface tension values were determined as decreasing from 71 mN/m to 40-50 mN/m in the presence of chitosan based bio-polymers with the substitution degrees between 25% and 45%. On the other hand contact angle values increased significantly in the case of chitosan based biopolymers. modifications with different initial mol ratios. The effect of these modified materials on the kinetics of oil emulsification was tested conducting in-situ size measurement studies and using a phenomenological dispersion model for the evaluation of data. This way the dispersion rate constants were able to calculated and used to compare the different conditions used to prepare emulsions. As a conclusion, the coalescence sub process that becomes dominant after 8 minutes of emulsification (in the case of oil only) totally disappeared in the presence of both chitosan and N-acylated chitosan. The rate of oil dispersion up to 8 minutes, however, did not change much in all the cases. The effect of modified chitosan on the kinetics was not significant. These were postulated as the possible changes in the configurations of the modified chitosan molecules due to the increased hydrophobic character and inter molecule interactions.