Fotoinitiation

Fotoinitiation refers to the process of initiating a chemical reaction through the absorption of light. In many polymerization reactions, particularly those involving monomers like acrylates and methacrylates, a photoinitiator molecule is added to the system. When this photoinitiator absorbs photons of a specific wavelength, it undergoes a transformation, typically fragmentation or hydrogen abstraction. This transformation generates reactive species, such as free radicals or cations. These reactive species then interact with the monomers, starting a chain reaction that leads to the formation of a polymer network. This technique is widely used in applications like UV curing of coatings, inks, adhesives, and in stereolithography 3D printing. The efficiency of fotoinitiation depends on the absorption spectrum of the photoinitiator, the wavelength of the light source, and the concentration of both the photoinitiator and the monomers. Different types of photoinitiators are available, categorized based on their mechanism of action, such as Type I photoinitiators that undergo unimolecular bond cleavage and Type II photoinitiators that require a co-initiator to generate radicals through bimolecular interaction. The ability to initiate polymerization precisely where light strikes makes fotoinitiation a valuable tool for spatial control in material fabrication and modification.