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Condensation Polymerization

  • Definition: A type of polymerization where monomers link together by eliminating a small molecule, such as water, rather than by adding to each other, which is characteristic of addition polymerization.

  • Key Examples:
      - Most natural polymers are formed via condensation polymerization.
      - Common natural polymers include:
        - Starch
        - Cellulose
        - Wool
        - Proteins

  • Additional Note: During this process, a small molecule like water is released, which is significant in the formation of complex structures.

Polyesters

  • Definition: Polymers formed when an ester functional group links the monomers together.

  • Applications: Commonly used in clothing fabrics.

  • Example:
      - Polyethylene Terephthalate (PET)
        - Monomers:
          - Terephthalic acid
          - Ethylene glycol
        - Structure: The synthesis of PET involves the reaction of terephthalic acid and ethylene glycol.

Proteins & Polyamides

  • Definition: Proteins are long chains of amino acids joined together through condensation polymerization.

  • Amino Acid Structure:
      - Each amino acid has:
        - Carboxylic acid Group (–COOH)
        - Amine Group (–NH2)

  • Peptide Bond:
      - Description: A covalent bond that forms between the carboxylic acid group of one amino acid and the amine group of another amino acid.
      - Significance: This bond is essential for forming the primary structure of proteins.

Comparison: PET and Proteins

  • Material Classification:
      - PET (Polyester):
        - Type: Polyester
        - Structure: Formed from two identical monomers, ethylene glycol, and terephthalic acid in a 1:1 ratio.
        - Functional Groups: Contains identical functional groups of –OH or –COOH.
      - Proteins (Polyamides):
        - Type: Polyamide
        - Composition: Can contain up to 20 different types of amino acids in any ratio.
        - Functional Groups: Each amino acid has two different functional groups: –NH2 and –COOH.
        - Key Differentiation: The variation in functionalities and structures leads to diverse protein types and functions compared to the uniform structure of PET.

Nylon

  • Discovery:
      - Discovered by Wallace Carothers at DuPont.

  • Composition:
      - Formed by combining adipic acid with hexamethylenediamine.

  • Historical Significance:
      - Nylon was notable for being the first synthetic substitute for silk.

  • Biomimetic Material:
      - Described as the first biomimetic material, indicating that it served as an inspiration from natural components for human application.