The invention describes a method for functionalization of polymers (introduction of a functional group Z) using a combination of hypervalent iodine (III) compounds (such as (diacetoxyiodo)benzene, PhI(OAc)
2
) with a trialkylsilyl compound R
3
SiZ or salts like NaZ. The reaction is carried out at mild conditions and can be used for efficient modification of polymers in solution or polymer surfaces. For example, the reaction of polystyrene or poly(4-vinylpyridine) with PhI(OAc)
2
and Me
3
SiN
3
yields azidated polymers. The products of the reaction could be further modified by copper-catalyzed click chemistry with an alkyne-terminated poly(ethylene oxide), leading to polymeric brushes with a hydrophobic backbone and a moderate density of hydrophilic side chains.