What are synthetic polymers? How are they classified? Give the characteristics of each type.

Synthetic polymers are long chain molecules made from small, repeating molecular units called monomers. They are artificially made by a process called polymerization, where monomers combine together to form polymer chains. These materials are present in many everyday items, including plastics, rubber, textiles, and other materials.

Synthetic polymers are typically classified into two main categories, based on their structure and how they are formed during polymerization: 1. Addition or chain-growth polymers 2. Condensation or step-growth polymers

These polymers are formed by the reaction between monomers with at least one double bond (alkene group) via an addition reaction. During the polymerization process, new monomers attach to the growing chain by opening the double bonds and forming single bonds with the chain. This process continues until the chain reaches the desired length. Some common examples of addition polymers include polyethylene, polypropylene, and polystyrene. Characteristics of Addition Polymers: - Tend to have a simple repeating structure - Usually synthesized from olefinic monomers containing C=C double bonds - Contains only atoms from the monomers in the polymer chain (no by-products) - Polymer chains can rapidly grow during polymerization

These polymers are formed by the reaction between monomers that contain two different functional groups (e.g. alcohol and carboxylic acid). During polymerization, the functional groups react to form a new bond, while a small molecule, such as water or methanol, is released as a by-product. This process continues until the desired polymer chain length is produced. Some common examples of condensation polymers include polyesters, polyamides (nylons), and polyurethanes. Characteristics of Condensation Polymers: - Often have a more complex structure compared to addition polymers - Synthesized from monomers containing two or more functional groups (e.g., -OH, -COOH, -NH2) - Polymerization results in the production of a small molecular by-product, like water or methanol - Polymer chains grow steadily as monomers react, and the rate is affected by the rate of by-product removal