How does a condensation polymer differ from an addition polymer? Give an example of each.

Polymerization is a chemical process that connects small molecules known as monomers into long, repeating chains to form polymers. There are several methods by which polymers can be synthesized, but the two primary types are condensation polymerization and addition polymerization.

In condensation polymerization, monomers react and join together with the simultaneous loss of small molecules like water or methanol. This is well represented in the production of polyester, where the elimination of water is part of forming the ester linkage that gives the polyester its structure. A simple representation of this reaction is as such: \[ HOOC-R_1-COOH + HO-R_2-OH \rightarrow [-OC-R_1-COO-R_2-O-]_n + (n-1)H_2O \].

On the other hand, in addition polymerization, unsaturated monomers (typically containing double bonds) link up without the loss of any other atoms or molecules. The monomers simply add to one another in a chain-growth fashion, as seen in the polymerization of ethylene to form polyethylene, showcased by the equation: \[ nCH_2=CH_2 \rightarrow [-CH_2-CH_2-]_n \].

Both types of polymerization are crucial in the production of various synthetic materials that we use in everyday life.

Understanding the relationship between monomers and polymers is central to grasping the basics of polymer science. Monomers are small, simple molecules that serve as the building blocks of polymers. They can join with other monomers, often in repeated sequences, to form complex and larger molecules known as polymers.

Take for instance, the monomers of ethylene glycol and terephthalic acid in the production of polyester. These monomers react through their functional groups – an alcohol and a carboxylic acid respectively – to form polyester chains while releasing water.

Similarly, the monomer ethylene undergoes addition polymerization to become polyethylene. The carbon-carbon double bond in ethylene is key as it opens up to link with other ethylene molecules, forming the long chains characteristic of polymers.

Essentially, monomers are the alphabets that make up the words (polymers), and the polymerization process is like forming sentences from these words to create a meaningful narrative – in this case, materials with diverse properties and applications.

The chemical structure of polymers determines their properties and functions. Polymers consist of long chains of atoms, primarily carbon, hydrogen, and sometimes other elements like oxygen, nitrogen, and sulfur. The arrangement of these atoms in the chain, the type of monomers involved, and the nature of the bonds connecting these monomers define the polymer’s characteristics.

Condensation polymers such as polyesters have a characteristic structure with ester linkages. The repeated unit in the chain often contains a part from both reacting monomers interlinked by an ester bond, as shown in the reaction for polyester synthesis. This arrangement imparts properties like strength and flexibility to the material.

For addition polymers like polyethylene, the chains consist of carbon atoms linked by single bonds, and the simplicity of the repeating -CH2- units imparts properties like toughness and plasticity. These polymers often exhibit high resistance to chemicals and electrical insulation properties due to their saturation and the absence of reactive double bonds.

A polymer's molecular weight, degree of branching, and cross-linking also play crucial roles in determining its mechanical strength, elasticity, and other physical properties.