A new approach to the preparation of two classes of block copolymers c
ontaining liquid-crystalline segments is reported. Copolymers 1 and 2
are constituted by polytetrahydrofuran and side-chain liquid-crystalli
ne polymethacrylate blocks, whereas block copolymers 3 consist of poly
styrene and main-chain liquid-crystalline polyester blocks. The synthe
tic procedures leading to copolymers 1-3 are extremely versatile and c
an be used to prepare a great variety of block copolymer architectures
. In both copolymer classes the chemically different blocks are strong
ly segregated in the solid and melt phases and undergo individual phas
e transitions. The mesophase transition temperatures of the liquid-cry
stalline blocks are very similar to those of the corresponding homopol
ymers, and their enthalpies are directly proportional to the content o
f the liquid-crystalline block.