Addition chain-growth polymerization and condensation step-growth polymerization are two major types of polymerization reactions that produce polymers with distinct structures and properties. Here are the key differences between them and how these differences affect the resulting polymer structure and properties:1. Monomers involved:Addition polymerization: Involves monomers with a carbon-carbon double bond C=C or another reactive group, such as a nitrile or isocyanate. The monomers are usually unsaturated compounds.Condensation polymerization: Involves monomers with two or more reactive functional groups, such as carboxylic acids, amines, or alcohols. The monomers are usually bifunctional or multifunctional.2. Reaction mechanism:Addition polymerization: The reaction proceeds through the formation of a reactive intermediate, such as a free radical, cation, or anion. The reactive intermediate adds to the double bond of another monomer, propagating the chain until termination occurs.Condensation polymerization: The reaction proceeds through the formation of a covalent bond between two monomers, accompanied by the elimination of a small molecule, such as water, methanol, or hydrogen chloride. The reaction occurs stepwise, with monomers reacting to form dimers, trimers, and so on, until high molecular weight polymers are formed.3. Molecular weight development:Addition polymerization: The molecular weight of the polymer increases rapidly during the early stages of the reaction, as the chain grows continuously.Condensation polymerization: The molecular weight of the polymer increases slowly and gradually, as the reaction proceeds through a series of stepwise reactions.4. By-products:Addition polymerization: No by-products are formed during the reaction.Condensation polymerization: Small molecules, such as water, methanol, or hydrogen chloride, are eliminated as by-products during the reaction.5. Polymer structure:Addition polymerization: The resulting polymers have a linear or branched structure, depending on the monomers and reaction conditions.Condensation polymerization: The resulting polymers can have linear, branched, or cross-linked structures, depending on the functionality of the monomers and reaction conditions.6. Polymer properties:Addition polymers: These polymers tend to have high molecular weights, and their properties depend on the monomers used and the degree of polymerization. They can be thermoplastic or elastomeric, with varying degrees of crystallinity and mechanical strength.Condensation polymers: These polymers can have a wide range of properties, depending on the monomers used and the degree of polymerization. They can be thermoplastic, elastomeric, or thermosetting, with varying degrees of crystallinity, mechanical strength, and chemical resistance.In summary, addition and condensation polymerization reactions involve different types of monomers, reaction mechanisms, and molecular weight development, leading to polymers with distinct structures and properties. Addition polymers are typically formed from unsaturated monomers and have a linear or branched structure, while condensation polymers are formed from bifunctional or multifunctional monomers and can have linear, branched, or cross-linked structures. The properties of the resulting polymers depend on the monomers used, the degree of polymerization, and the polymer structure.