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

Figure 5

(a) The orientational order parameter measured by birefringence, Δ𝑛, and (b) spontaneous shape change, 𝜆, versus 𝑇 (°C). For 𝑇>40^∘C, Δ𝑛 shows the least order for the shortest mesogens • CN50 and most for ▲ CN100 that with dimers are the longest. ◆ CN70, in the middle, has competing monomeric and dimeric tendencies. For spontaneous shape change, CN70 has the largest 𝜆 and highest 𝑇_𝑔. The solid curves, 6th order polynomial fits to the data, extrapolated to 0^∘C suggest glass transition temperatures, 𝑇_𝑔∼7--10^∘C for CN50 and CN100 and about 10 K higher for CN70. The dotted line is at 𝑇^∗=60^∘C.

(a)

(b)