A series of liquid crystalline (LC) poly(vinyl ether)s 1 was prepared by living cationic polymerization of a mesogenic vinyl ether monomer, 4-butoxyphenyl 4-((6-vinylhexyl)oxy)benzoate (11), in the presence of the HI/I2 (1/1 mol/mol) initiating system. The number average molar mass of polymers 1 increased linearly with the initial monomer to initiator molar ratio (M n = 3000−15 000 g mol-1, DPn ≈ 5−50), according to the living character of the polymerization, and their molar mass distribution was rather narrow (M w/M n = 1.10−1.15). Furthermore, two sets of AB diblock copoly(vinyl ether)s 2 and 3 were prepared by sequential polymerization of vinyl ether 11 and isobutyl vinyl ether (12) and chiral (S)-2-methylbutyl vinyl ether (13) respectively, by using the same HI/I2 system. While the average degree of polymerization of the LC block was kept constant (DPn ≈ 10), the length of the non-LC block was varied (DPn ≈ 2−25), according to the chosen feed conditions. An X-ray investigation proved that polymers 1 gave rise to a sequence of ordered smectic (F or I), smectic C, and nematic mesophases with increasing temperature. Their transition temperatures and entropies followed slightly different molar mass dependences, but each of them reached a saturation value at M n ≈ 6000 g mol-1. The same basic mesophase polymorphism was also observed for the LC block copolymers 2 and 3, thus suggesting that the chemically different blocks were microphase separated within the solid and LC phases.

A series of new liquid crystalline (LC) poly(viny1 ether)s with different molar masses was synthesized via a two-step procedure involving the preparation of functional matrices by living cationic polymerization of an o-chloroalkyl vinyl ether monomer followed by a grafting reaction of an azobenzene mesogenic unit onto them. By appropriately adjusting the experimental conditions, it was possible to predetermine the molar mass characteristics of the LC polymers. Each of the parent and modified poly(viny1 ether)s had a narrow molar mass distribution. The LC polymers were semicrystalline and formed a nematic mesophase, enantiotropic or monotropic in character. The transition temperatures increased with increasing molar mass up to a limiting value and then remained nearly constant. Accordingly, poly(viny1 ether)s with predetermined molar mass and narrow molar mass distribution could be prepared.