Impact of Catalyst on the Stability of Initiators on Au Substrate in Atom Transfer Radical Polymerization

Desorption of thiol-based self-assembled monolayers on gold surfaces makes surface-initiated atom transfer radical polymerization (SI-ATRP) challenging and results in reduced density “grafted from” polymer fi lm. In this work, in situ attenuated total refl ectance-Fourier transform infrared (ATR-FTIR) spectroscopy shows that copper-based catalysts typically used in SI-ATRP cause substantial desorption of bound thiol-based initiator fi lms from gold surfaces. Other reaction conditions factors such as low temperature, presence of radicals, and solvents selection have relatively minor effects in comparison. Indeed, the desorption of initiator fi lms is reduced from more than 80% to about 45% when CuCl catalyst is used for the ATRP of styrene instead of CuBr catalyst. However, the polymerization rate is signifi cantly slower in this case.