Peroxides

Definition

Peroxides are chemical compounds that contain an oxygen-oxygen single bond (–O–O–), and are often used as initiators in free radical polymerization processes. These compounds decompose to produce free radicals, which are crucial for initiating the polymerization of various monomers. Their ability to generate free radicals makes peroxides important for controlling the rate and efficiency of the polymerization reaction.

5 Must Know Facts For Your Next Test

1. Peroxides can be classified into different types, including organic peroxides, which are often used in polymer production, and inorganic peroxides, which may have different applications.
2. Common examples of peroxides used as initiators include benzoyl peroxide and hydrogen peroxide, which decompose at elevated temperatures to release free radicals.
3. The decomposition of peroxides is often temperature-dependent, meaning that controlling the temperature can influence the rate at which free radicals are generated.
4. Peroxides not only initiate the polymerization but can also affect the molecular weight and properties of the resulting polymers based on their concentration and type.
5. Safety precautions are essential when working with peroxides since they can be hazardous, often being flammable and reactive with other substances.

Review Questions

• How do peroxides function as initiators in free radical polymerization?
  • Peroxides function as initiators in free radical polymerization by decomposing to form free radicals. When a peroxide compound is exposed to heat or light, it breaks down into two radical species. These radicals then interact with monomer molecules, creating new radicals that propagate the polymerization process. This chain reaction continues, leading to the formation of long polymer chains.
• Compare and contrast organic peroxides and inorganic peroxides in terms of their roles in polymerization.
  • Organic peroxides, like benzoyl peroxide, are commonly used in polymerization due to their ability to generate radicals at lower temperatures, making them effective initiators for various monomers. In contrast, inorganic peroxides, such as hydrogen peroxide, may also initiate polymerizations but are less frequently used due to higher reactivity and potential side reactions. The choice between them depends on factors like desired reaction conditions and the specific properties needed in the final polymer.
• Evaluate the impact of peroxide concentration on the molecular weight and properties of polymers produced through free radical polymerization.
  • The concentration of peroxides used in free radical polymerization significantly affects both molecular weight and properties of the resulting polymers. Higher concentrations of peroxides typically lead to a greater number of initiating radicals, which can result in shorter polymer chains due to increased termination events. Conversely, lower peroxide concentrations allow for longer chain growth, enhancing molecular weight and potentially improving properties like strength and flexibility. Understanding this relationship is crucial for tailoring polymers for specific applications.

Related terms

Free Radicals: Highly reactive molecules or atoms that have unpaired electrons, capable of initiating chain reactions in polymerization.

Initiators: Substances that begin the polymerization process by generating free radicals, allowing for the growth of polymer chains.

Chain Reaction: A series of reactions where the product of one reaction initiates subsequent reactions, commonly seen in free radical polymerization.