Primary Amine-Functionalized Silicon Surfaces via Click Chemistry with α-Alkynyl-Functionalized Poly(2-aminoethyl methacrylate)

The direct preparation of α-alkynyl-functionalized poly(2-aminoethyl methacrylate) in its hydrochloride salt form (poly(AEMA)) via reversible addition-fragmentation chain transfer (RAFT) polymerization is reported. The controlled “living” polymerization of AEMA was conducted in DMSO at 45 °C using alkynyl-functionalized 4-cyanopentanoic acid dithiobenzoate (CTP) as the chain transfer agent (CTA), and 2,2′-azobis(2,4-dimethyl-4-methoxyvaleronitrile) (V-70) as the initiator. The resulting polymers display values of polydispersity index (PDI) lower than 1.2. Subsequently, the α-alkynyl-functionalized poly(AEMA) was attached to an azide-functionalized silicon wafer via click chemistry. Polymer-modified surfaces were evaluated using characterization techniques including ellipsometry, contact angle measurements, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and atomic force microscopy (AFM). A grafted polymer layer with average thickness of 15.2 nm and estimated grafting density of 0.39 chains/nm2 was obtained