Polycondensation: Forming Complex Polymers

Polycondensation is a critical process in polymer chemistry, involving the reaction of monomers with multiple functional groups to create large macromolecules. This page provides an overview of the polycondensation reaction mechanism and examples of polycondensation polymers.

Definition: Polycondensation is a polymerization process where monomers with at least two functional groups combine to form a macromolecule, releasing small molecules like water or ammonia as byproducts.

The page illustrates various monomers used in polycondensation reactions, including:

1. Terephthalic acid (HOOC-COOH)
2. 1,2-Ethanediol (HO-CH2-CH2-OH)
3. Hexanedioic acid (Adipic acid) (HOOC–(CH2)4–COOH)
4. 1,6-Diaminohexane (Hexamethylenediamine) (H2N-(CH2)6-NH2)
5. Phenol
6. Methanal (Formaldehyde)
7. Urea

Example: The reaction between terephthalic acid and 1,2-ethanediol produces a linear polyester, while the combination of hexanedioic acid and 1,6-diaminohexane forms a polyamide.

The document also presents the structures of various polycondensation products, including:

1. Linear polyester
2. Polyamide
3. Phenoplast
4. Aminoplast

Highlight: Unlike previously discussed polymers, polycondensation products do not contain carbon-carbon multiple bonds in their main chain.

The page emphasizes that polycondensation can occur between identical or different monomers, as long as they are at least bifunctional (having two reactive functional groups). Examples of bifunctional molecules include:

• Diols (HO-R-OH)
• Dicarboxylic acids (HOOC-R-COOH)
• Diamines $H2N-R-NH2$

Vocabulary: Bifunctional molecules are compounds with two reactive functional groups capable of participating in chemical reactions.

When these molecules combine, they form linear macromolecules. Molecules with more than two reactive functional groups can create branched or cross-linked structures.

The page concludes with a summary of the polycondensation process:

Quote: "In polycondensation, monomers with at least two functional groups combine to form a macromolecule, releasing small molecules such as water or ammonia as byproducts. The resulting plastics are called polycondensates."

Lastly, the document lists some common trade names for polycondensation products:

1. Trevira
2. Diolen
3. Dacron
4. Nylon®
5. Bakelite
6. Resinol®
7. Resamin
8. Pollopas

These materials showcase the wide range of applications for polycondensation polymers in various industries.