End‐functionalized polystyrene by ATRP: A facile approach to primary amino and carboxylic acid terminal groups

Abstract

Abstract Monoamino‐terminated and monocarboxylic acid‐terminated polystyrenes containing active halogenated end groups were prepared by atom transfer radical polymerization (ATRP) using the so‐called initiator method and protective group chemistry. α‐Chloropropionates were synthesized and utilized as initiators containing the tert ‐butoxycarbonyl ( t ‐BOC)‐protected amino and the tert ‐butyl ( t ‐Bu)‐protected carboxylic acid function, respectively. Optimum polymerization conditions were attained using CuCl/ N,N,N ′, N′ ′, N′ ′‐pentamethyldiethylenetriamine (PMDETA) as catalyst and 10 vol % n ‐butanol as homogenizing agent at 110 °C. However, targeting larger quantities an alternative route was established employing 50 vol % N,N ‐dimethylformamide (DMF). Subsequent hydrolysis of the ω‐ tert ‐butoxycarbonyl polystyrenes afforded well‐defined polymers with quantitative deprotection of the functional groups. Comparatively, thermolytic cleavage of the protective sites was studied. 1 H NMR verified the quantitative removal of the t ‐BOC‐protecting groups. Furthermore, the resulting α‐amino‐ω‐chloro polystyrenes were reacted with Sanger reagent to confirm the existence of the thereby converted primary amino groups. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3845–3859, 2009