Cylindrical brushes with a macromolecular backbone and well-defined side chains of different length (4 less than or equal to P-n(sc) less than or equal to 38) were synthesized by polymerization of macromonomers. The effect of side chain length on the intermolecular order has been investigated by means of X-ray scattering on the melt-extruded samples. The increase of the side chain molar mass results in an increase of the intermolecular distance d according to d similar to (M-n(sc))(0.476). The contour length of the cylindrical brush polymers per main chain monomer unit, 1(m), was determined to slightly vary with side chain molar mass M-n(sc) according to l(m) similar to (M-n(sc))(0.059). The resulting values are much less than the maximum extension, l(m) = 0.25 nm, which is found to be almost independent of side chain molar mass. Also, supermolecular structure formation of a random copolymer brush prepared by radical copolymerization of methacryloyl end functionalized polyvinylpyridine and polymethylmethacrylate macromonomers has been observed and is interpreted as a consequence of intramolecular phase separation. (C) 2004 Published by Elsevier Ltd.