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

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 (DP) over bar (n) = 240 and 1500 served as the backbone. The PLMA side chains of the brushes carry long alkyl chains. GPC and H-1 NMR measurements confirmed the successful formation of the PLMA cylindrical brushes. The side chains were cleaved from the cylindrical brushes by transesterification. GPC and H-1 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, R-g/R-h, is in the range of 1.2-1.3, indicating that the PLMA cylindrical brushes are semiflexible 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 degrees C, indicating the alkyl side chains of the PLMA chains in the double-grafted cylindrical brushes are crystallizable.