Photopolymerization of a Semifluorinated Difunctional Liquid Crystalline Monomer in a Smectic Phase

Abstract

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.

Aliphatic chain length effects on photopolymerization kinetics and structural evolution of polymerizable lyotropic liquid crystals

“…Complete polymerization occurs in approximately 20 min compared to approximately 5 min for the reactive LLC monomer systems. These results confirm that the enhancements in polymerization rates observed in the ordered LLC system are due to the combined effects of diffusional limitations on the propagating polymer in addition to the segregation of the polymerizable groups [36].…”

Anisotropic networks, elastomers and gels

“…Chiral smectic networks Macroscopically uniaxially oriented chiral smectic C mesogenic monomers in the smectic state [ 26,27] gives rise to smectic networks. These anisotropic networks (SmC*) networks with a uniform directional ordering of the dipoles at the optically active centre have been exhibit similar properties to those of the analogous nematic networks, but with an additional layer structure.…”

Photopolymerized low‐surface‐energy coatings based on a novel fluorinated ether acrylate

“…2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-Pentadecafluoro-1-octanol (Aldrich; 98%), triethylamine (TEA; Aldrich; 99%), and trifluoroacetic acid (Aldrich; 99%) were used as received. Tetrahydrofuran (THF) was freshly distilled over Na(s) and benzophenone.…”

“…4 One of the most popular strategies for designing films with low surface energy is to incorporate fluorine into the polymers that comprise the coating. 5 Fluoropolymers 6 and semifluorinated molecules 7 offer many properties desirable in coatings, such as high thermal stability, chemical and oxidative resistance, 8,9 low refractive indices, 10,11 and substantial hydrophobicity. The hydrophobic nature reflects low values of cohesive energy density and surface energy.…”