When I immersed a hydrophobic silicon wafer in the BSA-Br initiator solution and then tried to conduct ARGET ATRP polymerisation for two hours, the brushes results were very thin under 7 nm, While when I test the same solution on a chip without BSA-Br coating the thickness of brushes was favourable!
In comparison with free radical polymerization, one of the main characteristics of controlled polymerization such as RAFT and ATRP is that you cannot reach high molecular weight polymers. However, the molecular weight also depends on the monomer: initiator ratio. So you can try free radical polymerization instead of ATRP or increase the M/I ratio and reaction time to obtain a high MW and a thicker layer.
Dear Elanmugilan,
Most probably, you have a low amount of Br groups in BSA-Br, which causes the low grafting density of the final brush and, as a consequence, the low thickness of the final brush. If the brushes achieve higher thickness on initiator monolayers (such as 11-(Trichlorosilyl)undecyl 2-bromo2-methylpropanoate), the problem is grafting density. The introduction of more Br groups to BSA may be one of the solutions.
Best regards, Andriy
Zahra Nadizadeh Thank you for the answer, I'm limited to the ATRP technique
Andriy R. Kuzmyn Thank you for your response. I agree that it may be necessary to verify the quantity of Br attached to BSA.
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