SurfaceInitiated

Surfaceinitiated polymerization refers to polymerization processes in which polymer chains are grown from initiator-functionalized surfaces, producing polymer brushes that extend into a surrounding medium. The initiator groups are covalently attached to a substrate, and polymer growth proceeds from these sites, yielding dense, uniform grafted layers.

Common approaches are based on controlled radical polymerization, enabling precise control of chain length, architecture, and density. Notable variants include surface-initiated atom transfer radical polymerization (SI-ATRP), surface-initiated reversible addition–fragmentation chain-transfer polymerization (SI-RAFT), and surface-initiated ROMP (SIR). Traditional surface polymerization from immobilized initiators also exists, though with less control.

Substrates and monomers: Surfaces such as silicon wafers, glass, gold, and polymer films can be functionalized with initiators (e.g., using silane chemistry or thiol-based self-assembled monolayers). Monomers commonly used include styrene, acrylates, and methacrylates; more specialized monomers enable responsive or functional brushes.

Applications: Surfaceinitiated polymerization is used to tailor surface properties, including wettability, adhesion, antifouling, biocompatibility, and optical or electrical characteristics. It is also employed in biosensors, microfluidics, and as interfacial layers in electronics.

Characterization and control: Brush thickness and graft density are controlled by initiator density, polymerization time, and monomer reactivity. Thickness is measured by ellipsometry or atomic force microscopy; surface properties are assessed by contact angle measurements or spectroscopy.

History: The concept emerged in the late 20th century with the development of controlled/living radical polymerization, with SI-ATRP and related methods pioneered by researchers including Matyjaszewski and Hawker.