The equilibrium phase diagram of mixtures of linear poly(2-phenoxyethylacry
late) of molecular weight M-w = 181 000 g/mol, and the low molecular weight
liquid crystal 4-cyano-4'-n-pentyl-biphenyl known as 5CB has been establis
hed using polarized optical microscopy and differential scanning calorimetr
y (DSC). The diagram exhibits an upper critical solution temperature and th
ree main transitions: crystalline + isotropic (C + I) to nematic + isotropi
c (N + I), (N + I) to isotropic + isotropic (I + I), and (I + I) to isotrop
ic (I). The (C + I) to (N + I) transition is observed by DSC, while the (N
+ I) to (I + I) transition is detected by optical microscopy and DSC, and t
he (I + I) to (I) transition only by optical microscopy. The results were s
uccessfully analyzed within a theoretical model combining the Flory-Huggins
lattice theory for isotropic mixing and the Maier-Saupe theory of nematic
ordering. (C) 2000 Elsevier Science Ltd. All rights reserved.