PHOTOPOLYMERIZATION OF A SEMIFLUORINATED DIFUNCTIONAL LIQUID-CRYSTALLINE MONOMER IN A SMECTIC PHASE

The photoinitiated polymerization of a semifluorinated difunctional mo nomer, 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 isotropi c phase, the polymer chain kinetic lifetime is markedly longer in the smectic phase, presumably due to a relatively large decrease in termin ation 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 sme ctic phase of the monomer, it is possible to ''lock-in'' the order of the smectic phase in the cross-linked network generated.