Phd Degree / Doktora

Permanent URI for this collectionhttps://hdl.handle.net/11147/2869

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Subject: search.filters.subject.Polylactide

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  • Doctoral Thesis
    Macromolecular Design of Hydroxyl Functional Linear and Star-Shaped L-Lactide and ?-Caprolactone Biodegradable Polyesters Utilizing Biosafe Catalysts for Biomedical Applications
    (Izmir Institute of Technology, 2017) Başalp, Dildare; Tıhmınlıoğlu, Funda
    In the present study, macromolecular design of homo and copolymers of lactide (LA) and ε-caprolactone (CL) in different structures by the use of biocompatible catalysts and co-initiators were performed to satisfy a need of tailor-made bioassimilable polymeric structures without any hazardous metal contaminants for various medical applications. Linear and star shaped (di, tetra and hexa functional) poly(L-lactide) (PLLA) and poly(ε-caprolactone) (PCL) homo/copolymers were synthesized by using bismuth(III)acetate (Bi(III)Ac) and creatinine as biosafe catalysts and ethylene glycol, pentaerythritol and myo-inositol as co-initiators. The effect of catalyst type on polymer properties was observed by differences in crystalline structure. Crystalline and amorphous linear and star shaped PLLAs were obtained by using Bi(III)Ac and creatinine as catalysts, respectively. The activity of creatinine was very low comparing to Bi(III)Ac and SnOct2 catalysts. The reactivity of LA monomer was found to be higher than that of CL monomer. The high molecular weight polymers having low PDI values were obtained by using Bi(III)Ac catalyst contary to creatinine catalyst. The decrease in glass transition temperatures and molecular weights of synthesized PLLA and PCL homo/copolymers were observed with the increase in amount of co-initiators due to the decrease in chain length and disruption of crystal formation. The cytotoxicity properties of the catalysts and synthesized linear and functional homo/co PLLAs and PCLs were carried out according to MTT assay. Cytotoxicity of Bi(III)Ac was found as lower than that of SnOct2. Creatinine and the synthesized polymers did not show any cytotoxic properties. The observation of no cytotoxic effect of creatinine catalyst results in the biosafe usage of creatinine catalyst instead of toxic SnOct2 for the synthesis of moderate or low molecular weight homo/co PLLAs and PCLs in bioapplications.
  • Doctoral Thesis
    Feasibility of Eugenol Encapsulated Poly (lactic Acid) (pla) Films Via Electrospinning as a Novel Delivery System for Volatile Compounds in Food Packaging Systems
    (Izmir Institute of Technology, 2017) Arserim Uçar, Dilhun Keriman; Korel, Figen; Korel, Figen; Yam, Kit L.
    Food safety and quality are important issues in food industry. The aim of this research was to evaluate the feasibility of delivering eugenol via poly(lactic) acid (PLA) emulsion fibers-grafted PLA films with bacterial cellulose into the package headspace. For this purpose, first, bacterial cellulose crystals as a natural carrier for eugenol were produced. The influence of hydrolysis temperature, time, and acid to cellulose ratio, acid concentration and type with the addition of the neutralization step on the structure, and the properties of bacterial cellulose crystals were studied. Nanocrystals, which had high thermal stability and high crystallinity bacterial cellulose, were produced. Bacterial cellulose stabilized oil-in-water Pickering emulsions were produced as carriers for eugenol. The emulsion formulations consisting of cellulose fibers and crystals, eugenol, and surfactants were characterized for food packaging applications. PLA films were produced with obtained eugenol emulsions and poly(lactic) acid which were obtained via the electrospinning method. The produced films revealed a significant antibacterial effect on L. innocua, and E. coli inoculated tomato stem scars as real food model. The fabricated films also had significant antifungal activity on B.cinerea inoculated table grapes. Developed novel biodegradable-PLA cellulose composite films had a great potential for delivering bioactive volatile compounds for intelligent food packaging applications. The findings of this research supports the technical feasibility of delivering eugenol for antimicrobial active packaging applications via electrospun fibers.