Double-grafted cylindrical brushes: Synthesis and characterization of poly(lauryl methacrylate) brushes

Abstract

Double-grafted cylindrical brushes with poly(lauryl methacrylate) (PLMA) as the side chains were synthesized using the grafting-from strategy via atom transfer radical polymerization (ATRP). The polyinitiator poly[2-(2- bromoisobutyryloxy)ethyl methacrylate] (PBIEM) with DP̄n = 240 and 1500 served as the backbone. The PLMA side chains of the brushes carry long alkyl chains. GPC and 1H NMR measurements confirmed the successful formation of the PLMA cylindrical brushes. The side chains were cleaved from the cylindrical brushes by transesterification. GPC and 1H NMR results indicate that the initiating efficiency of the bromoester groups on the backbone for the bulky monomer was in the range of 0.34 < f < 0.67. Static and dynamic light scattering show that the ratio of the radius of gyration to the hydrodynamic radius, Rg/Rh, is in the range of 1.2-1.3, indicating that the LMA cylindrical brushes are semi-flexible in solution. Atomic force microscopy (AFM) measurements show that short PLMA brushes exhibit a spherical morphology while the long brushes exhibit a worm-like structure. DSC displayed melting peaks at around -30°C, indicating the alkyl side chains of the PLMA chains in the double-grafted cylindrical brushes are crystallizable. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.