CORRELATION OF MODEL COMPOUNDS AND LATERALLY ATTACHED SIDE-CHAIN LIQUID-CRYSTALLINE POLYNORBORNENES WITH AN 11-CARBON SPACER

Poly{5-[[[11'-[2 '',5 yl]undecyl]oxy]carbonyl]bicyclo[2.2.1]hept-2-ene }s exhibit an enantiotropic nematic mesophase when n = 2-12. In contra st to the corresponding reference polymers with a 1-carbon spacer, non e of these polymers with an 11-carbon spacer crystallize if their mole cular weight is sufficiently high. Although the corresponding luoro-4' -n-alkoxyphenyl)ethynyl]-2-undecylbenzenes exhibit only a monotropic n ematic mesophase when n = 2, 4, 6-11, their isotropization temperature s are nearly identical to those of the polynorbornenes, and they are t herefore appropriate models of the polymers. The polymers (DPn = 14-15 8, pdi = 1.14-1.37) were prepared by ring-opening metathesis polymeriz ation of 5-{[[11'-[2 '',5 nyl]undecyl]oxy]carbonyl}bicyclo[2.2.1]hept- 2-enes in THF using Mo(CHCMe2-Ph)(N-2,6-(Pr2Ph)-Pr-i)((OBu)-Bu-t)(2) a s the initiator. Their thermotropic behavior becomes independent of mo lecular weight at approximately 30 repeat units.