Dissertation > Excellent graduate degree dissertation topics show

Synthesis, Characterization of a Schiff-base Titanium Complex and Its Application as an Initiator for Ring-opening Polymerization of D, L-Lactide

Author: LiXiang
Tutor: WangYuanLiang
School: Chongqing University
Course: Biomedical Engineering
Keywords: Polylactic acid Schiff base Titanium Ring-opening polymerization
CLC: R318.08
Type: Master's thesis
Year: 2011
Downloads: 43
Quote: 0
Read: Download Dissertation

Abstract


Polylactic acid has good biocompatibility and biodegradability, has become in recent years, the field of biomedical research hotspot. The metal catalyzed lactide ring-opening polymerization as synthetic polylactic acid material is an important means of controlled polymerization of lactide can be achieved by selecting the appropriate ligand and metal. Requires not only the catalyst of the high activity of the catalyst on the metal atom and the lactide the strong complexing ability of the carbonyl oxygen atom, also need to increase the catalyst OM (M metal atom) the electron density of the oxygen atoms, in order to improve its offensive lactide the ability of the ester carbonyl carbon atom, while the catalytic polymerization reaction need to consider the effects of prolonged high-temperature decomposition of metal complexes, therefore considered to increase the electron rich atoms, such as N-atom to form a coordination bond with the metal atom in the metal complexes Increased stability of the complexes. Taking into account the lactide ring-opening reaction intramolecular and intermolecular transesterification side reactions the reaction can be selected having a larger steric hindrance of the ligand with the metal complex to reduce the occurrence of side reactions, to reduce the polymerization product of molecular weight dispersion. Based the above highly active catalyst design ideas, 3,5 - di-tert-butyl-salicylaldehyde, ethylenediamine and ethyl titanate as raw material, the synthesis of a new type of titanium Schiff base complexes, then The Schiff base complexes as catalyst D, L-LA ring-opening polymerization of lactide monomer and catalyst in the polymerization reaction, the molar ratio of the polymerization temperature and the polymerization reaction time of these three factors on the polymerization reaction impact, the evaluation index is a polymerization product of polylactic acid having a number average molecular weight and molecular weight polydispersity (PDI value); the polylactic acid and the catalytic synthesis of structural characterization and performance studies (including thermal performance degradation properties in vitro and biocompatible resistance). The main contents and conclusions are as follows: ① salicylaldehyde with ethylenediamine reaction with push electron-(t-Bu) generated Schiff base ligand and ethyl titanate equimolar water transesterification reaction occurs Schiff base titanium complexes, infrared spectroscopy, nuclear magnetic resonance spectroscopy showed that the N atom of the ligand and Ti successfully coordinated O atom and the Ti covalent bond; the XRD, elements, single crystal, SEM analysis showed that the complex layered solid, complex crystals belong to the triclinic space group C2 / c, to approximate rhombic plane constituted by covalent bond formation to two Ti two O symmetric spatial structure of the center; TG / DSC analysis shows the complex in 360 ℃ started to decompose, and have good thermal stability. ② the titanium Schiff base with the material used in the D, L-LA ring-opening polymerization, N [M] / n [I] = 2600 The results show that the polymerization time was 16h, the polymerization temperature is 160 ℃ polymerization monomers the maximum conversion rate . From catalytic experimental results can also be seen, a molecular weight dispersity of the obtained polylactic acid are in the range of 1.09 to 1.24, which indicates that the catalyst of lactide ring-opening having a higher molecular weight dispersity controllability. ③ number of stannous octoate catalyzed ring-opening lactide synthesis average molecular considerable dispersity of the poorer the polylactic acid (SP) for control, the investigated Schiff base titanium catalyzed the synthesis of the polylactic acid (TP) the physicochemical properties, including the pro / hydrophobic properties (a static water contact angle, the water absorbency of the evaluation index) and material degradation of performance. Degradation of performance evaluation in vitro degradation experiments in real time. The results obtained are as follows: 1) the contact angle and the water absorption ratio of the order of the two materials were: SP LT; TP and SP GT; TP, TP is less hydrophilic. 2) degradation Experimental results show that: the degradation of the two materials were similar, but TP degradation than SP slow. (4) to glass blank, SP for control TP preliminary cell compatibility visits (observation of cell morphology and cell proliferative capacity), and results show that the the TP's Cytocompatibility than the SP somewhat less.

Related Dissertations

  1. Studies on Synthesis, Characterization and Properties of Fe-V Co-doped TiO2 Catalyst,O614.411
  2. Preparation and Characterization of the OCS/PLLA Composite Film for Biomedical Materials,R318.08
  3. Studies on the Preparation and Nutrient Release Characteristics of Low Molecular Weight Polylactic Acid Coated Urea,S145.6
  4. Iron, lanthanum -doped nano TiO \u003csub\u003e 2 \u003c/ sub\u003e Preparation and photocatalytic properties,O614.411
  5. Synthesis and Asymmetric Catalytic Behaviors of Chiral Imine and Dimines Schiff Bases,O621.3
  6. Theoretical Analysis of the Circular Dichroism Spectra of Transition Metal Schiff-Base Complexes,O641.4
  7. The Study on the Tribological Property of Schiff Base Copper (Ⅱ) Complex in Different Basis Lubricating Oils,TE624.82
  8. Influence of Various PH and the Treating Time on Mechanical Property and Surface Structure of Ni-ti Orthodontic Wire,R783.5
  9. Inorganic filler of the modified polylactic acid,TQ320.1
  10. Inorganic and inorganic - organic hybrid Zn -based catalysts and catalytic L- lactide ring-opening polymerization of L- polylactic acid applied research,O631.3
  11. 1,4 - bis (4 - amino-2 - (trifluoromethyl) phenoxy ) benzene -type Schiff base imide copolymer synthesis and characterization,O631.3
  12. Schiff base Synthesis, Characterization and Antibacterial Properties,O641.4
  13. Research on the Resistance of PLA Fiber to Wet-hot, Dry-hot, Acid and Alkali,TQ342
  14. Preparation of Zeolite Doping Nano-TiO2 and Research of the Photocatalytic Properties,TB383.1
  15. Analyse of Expansive Open-door Laminoplasty with Titanium Mesh Cages and Laternal Mass Internal Fixation by Posterior Approach of Cervical Spondylotic Myelopathy,R687.3
  16. Studies on the Preparation and Properties of ACF/PLGA Scaffolds for Bone Tissue Engineering,R318.08
  17. Evaluation of Biocompatibility of Titanium Alloy Coating by Polyurethane,R318.08
  18. Preparation, Characterization and Performance of the Bio-coatings on the Surface of Pure Titanium Based on Micro Arc Oxidation,R318.08
  19. Deep manned submersible pressure hull fatigue reliability analysis of titanium,U661.4
  20. Preparation and Performance of Meloxicam Loaded PLA Sustained-release Microspheres,R943
  21. Temperature-sensitive polypeptide polymer design, synthesis and properties,O631.3

CLC: > Medicine, health > Basic Medical > Medical science in general > Biomedical Engineering > General issues > Biomaterial
© 2012 www.DissertationTopic.Net  Mobile