Polar Liquid Crystal Elastomers Cross Linked Far from Thermodynamic Phase Transitions: Dislocation Loops in Smectic Clusters

Figure 3

An overview of the nematic networks of • CN50, ◆ CN70, and ▲ CN100. The solid curves are lines of constant number of smectic layers correlated in a cluster, 𝜉/𝑑 (shown to the right of the figure), with 𝜉, the layer correlation length, and 𝑑, the layer spacing (Figure 2), measured by synchrotron radiation. 𝜉/𝑑 is maximum (~28.3 layers for CN70, and 31.5 layers for CN100) on the dashed line 𝑇^∗=60^∘C between CN70 and CN100 compared to about 10 layers at 𝑇_𝑖 where smectic clusters first appear. 𝑇_𝑐 is the cross-linking temperature. 𝑇_𝑔 is the glass transition temperature. The maximum number of correlated layers in CN50 is 12 at ~40^∘C and is only about 2 at 𝑇_𝑖 and 10 at 𝑇_𝑔. The dashed curve for 𝑇_𝑖 is deduced from measurements of spontaneous shape change, 𝜆(𝑇), measured in the optical microscope, discussed in Section 2.3. 𝑇_𝑔 is estimated from the 𝜆(𝑇)’s in Figure 4.