What method of painting combines molecules to form a larger structure?

The process of polymerization involves the chemical reaction in which small molecules, known as monomers, bond together to form larger, more complex structures known as polymers. This transformation significantly alters the properties of the original substances, often resulting in materials that have enhanced durability, flexibility, and resistance to environmental factors. In the context of paints and coatings, polymerization is a crucial process as it affects how the paint cures and adheres to surfaces.

In contrast, emulsification refers to mixing two immiscible liquids, like oil and water, to create a stable mixture, which does not involve the chemical bonding characteristic of polymerization. Solvation pertains to the interaction between a solute and a solvent in a solution and does not encompass the structural changes involved in polymer formation. Coagulation involves the process of particles clumping together, which typically occurs in colloidal suspensions and has different implications in coating applications.

Thus, among the given options, polymerization is the most relevant to the context of paint and coatings, emphasizing the significant role it plays in producing effective and long-lasting finishes.