Question

In ___________ polymerization, the monomer units simply combine over and over again to form the polymer's long chain.

Short answer

In addition polymerization, the monomer units simply combine over and over again to form the polymer's long chain.

Step-by-step solution

Understand the Concept of Polymerization

Polymerization is the process of creating a polymer from monomer units. There are two main types of polymerization: condensation polymerization and addition polymerization. Let's explore both types briefly to see which one fits the description provided in the exercise.

Condensation Polymerization

In condensation polymerization, monomers join together by releasing a small molecule, like water or methanol, as a byproduct. Condensation polymerization results in polymers with a variety of molecular weights and more complex chains. However, this type of polymerization does not involve monomers merely combining over and over again without the release of a smaller molecule in the process.

Addition Polymerization

In addition polymerization, monomer units combine directly with one another to form a single polymer chain. This process typically involves reactive species such as free radicals, cations, or anions. The initial reactive species adds to the monomer unit, creating a new reactive end that can then add another monomer. This process continues, with each monomer simply attaching to the growing chain without losing any atoms, forming a long polymer chain.

Identify the Type of Polymerization

Based on the description given in the exercise, where the monomer units simply combine over and over again to form the long polymer chain, it resembles addition polymerization. Therefore, the answer should be: In addition polymerization, the monomer units simply combine over and over again to form the polymer's long chain.

Key concepts

addition polymerization

Addition polymerization refers to the process where monomer units join to form a polymer without the loss of any atoms. It is a straightforward process where each monomer unit attaches directly to the growing polymer chain. This process generally occurs via free radical, cationic, or anionic mechanisms, depending on the type of chemical bonding.

For instance, a free radical mechanism involves an unpaired electron that initiates the poly chain by reacting with a monomer. This turns the monomer into part of the chain, making it reactive and ready to add the next monomer.

• Monomers react without losing atoms.
• Long chains are formed in a stepwise addition of monomers.
• Free radicals, cations, or anions are key players in this reaction.

Thanks to its simplicity and efficiency, addition polymerization is widely used in creating plastics like polyethylene and polystyrene, which are essential in everyday life.

condensation polymerization

Condensation polymerization is a type of polymerization where monomers join together, releasing small molecules as byproducts. These byproducts are usually water or methanol, making this process different from addition polymerization.

During condensation polymerization, two functional groups on the monomers react, creating a covalent bond and a small molecule like water gets expelled. This reaction continues, gradually forming a larger polymer chain.

• Involves loss of small byproducts like water or alcohol.
• Produces polymers with more complex structures.
• Commonly used to synthesize polyesters and polyamides.

Condensation polymerization is essential in producing various materials like nylon and polyester, playing a crucial role in textile manufacturing.

monomer units

Monomer units are the building blocks of polymers, small molecules that can join together to form larger structures, called polymers. Each monomer possesses specific features that allow it to bond with other monomers in a repeating sequence, similar to pieces in a chain link.

In addition polymerization, these units join together directly. While in condensation polymerization, the joining of monomers leads to the release of smaller molecules.

• Can form linear or branched structures.
• Basic units like ethylene are used in addition polymerization.
• Specialized monomers with functional groups participate in condensation polymerization.

Understanding monomers is crucial in the field of materials science as it allows scientists to design polymers with specific properties, enhancing functionality and application in diverse industries.