Synthesis and polymerization of liquid crystalline donor-acceptor monomers

The synthesis and polymerization of the following liquid crystalline monomers (containing both a vinyl ether group (electron donor) and a maleimide group (electron acceptor) within the same molecule) are described: 4-[(4-maleimidobenzoyl)oxy]phenyl 4-[[4-(vinyloxy)butyl]oxy]benzoate (1), 4-[[11-[(4-maleimidobenzoyl)oxy]undecyl]oxy]phenyl 4-[[4-(vinyloxy)butyl]oxy]benzoate (2), and 4-[[6-[(4-maleimidobenzoyl)oxy]hexyl]oxy]phenyl 4-[[4-(vinyloxy)butyl]oxy]benzoate (3). In the absence of photoinitiators, direct photolysis of a mixture of monomers 2 and 3, oriented in the nematic phase, led to initiation of polymerization and the formation of an ordered nematic LC polymer network. The use of a nonliquid crystalline model substance, N-[4-[[[4-(vinyloxy)butyl]oxy]carbonyl]phenyl]maleimide (4), showed that irradiation with a high-power microwave lamp, without the presence of photoinitiators, resulted in fast and efficient polymerization.