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Chemical Modification of Cellulose and Starch Via Two Methods: Synthesis of Their Water Soluble Derivatives & Preparation of Their Superabsorbent Hydrogels and Synthesis of Polymers with Fine Structures and Design Functional Groups by ATRP Method

Seidi Ghalehgah, Farzad | 2011

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 42085 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Pourjavadi, Ali
  7. Abstract:
  8. Hydrogels are crosslinked hydrophilic polymers that are capable of imbedding large amounts of water or biological fluids usually to equilibrium. Because of their unique properties, these materials have become ubiquitous and indispensable materials in many applications in recent years. Synthetic methods have produced numerous hydrogel materials with excellent properties. However, their nonbiodegradability might pose long-term environmental problems and limit their use. As a consequence, various research groups have put considerable amounts of effort and resources toward development of new absorbent materials from natural polymers such as polysaccharides. In this research, new hydrogel superabsorbent based on carboxymethylcellulose and acrylate-starch has been synthesized and their swelling behavior in various condition has been investigated. Cellulose and starch are biopolymers materials with fascinating structure and properties, which are available at low cost for various applications. But surely they cannot be the ‘‘best’’materials for every conceivable application. The most frustrating aspect of cellulose is insolubility in water and in most organic solvents. In the present research novel cellulose and starch derivatives with different functional groups has been synthesized which were found to be soluble in water and common organic solvents. Atom Transfer Radical Polymerization (ATRP) is among the most effective used methods of controlled radical polymerization (CRP). This living, synthetic process can be shut down or re-started at will, depending on how the temperature and other conditions of the reaction are varied. ATRP is an exceptionally robust way to uniformly and precisely control the chemical composition and architecture of polymers as well as the uniform growth of every polymer chain, while employing a broad range of monomers. In this research, new benzylic ATRP initiator was synthesized and used for preparation of amino end functionalized polystyrene with narrow polydispersity. In another research, a dendritic copolymer with PEG core and poly(N-isopropylacrylamide) arms has been prepared and selfassembly of this copolymer in different conditions has been investigated. Finally, hemoglobin and also human blood has been used as a novel catalyst for ATRP.
  9. Keywords:
  10. Hydrogel ; Polysaccaride ; Starches ; Cellulose ; Atom Transfer Radical Polymerization

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