Photopolymerization of a semifluorinated difunctional liquid crystalline monomer in a smectic phase

The photoinitiated polymerization of a semifluorinated difunctional monomer, which can exist in both a smectic liquid crystalline phase and an isotropic phase, has been investigated as a function of temperature. Although the maximum rate attained for photoinitiated polymerization in the smectic phase is lower than for polymerization in the isotropic phase, the polymer chain kinetic lifetime is markedly longer in the smectic phase, presumably due to a relatively large decrease in termination rate compared to propagation. The results also suggest that both termination and propagation rate processes are diffusion controlled. By conducting polymerization at a temperature corresponding to the smectic phase of the monomer, it is possible to ''lock-in'' the order of the smectic phase in the cross-linked network generated.