Click Chemistry Grafting of Poly(ethylene glycol) Brushes to Alkyne-Functionalized Pseudobrushes

A versatile method for the grafting of azide-terminated polymer chains to alkyne-functionalized pseudobrushes by the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition has been developed. First, poly[(propargyl methacrylate)-r-(glycidyl methacrylate)-r-(methyl methacrylate)] random copolymers with monomer ratios of respectively 27/27/46, 41/31/28, and 45/55/0 were synthesized by RAFT polymerization. Then, dense alkyne-functionalized pseudobrushes were grafted in melt by thermal ring-opening of the glycidyl groups by the silanols from the silicon Substrate. Finally, the grafting of tailor-made (alpha-methoxy-omega-azido-poly(ethylene glycol)s (M-w similar to 5000, 20 000, and 50 000 g/mol) by Cu(I)catalyzed Huisgen 1,3-dipolar cycloaddition was performed in sealed reactors at 60 degrees C for 72 h using a polymer weight fraction of 10% in tetrahydrofuran and Cu(PPh3)(3)Br/DIPEA as the catalytic system. Alkyne-functionalized pseudobrushes and poly(ethylene glycol) brushes were characterized by ellipsometry, scanning probe microscopy, and water contact angle measurements. This "grafting-to" approach represents a fast and versatile method to provide thick and homogeneous polymer brushes with a high surface coverage. A major benefit of this strategy is the tunable and versatile tethering of alkyne functionalities to silicon substrates using it straightforward spin-coating procedure.