Studies in Mixed Liquid Crystals of Structurally Similar Mesomorphs and Non-mesomorphs

Applied Chemistry Department

Applied Physics Department, Faculty of Technology and Engineering, M. S. University of Baroda, Baroda-390 001

Manuscript received 17 June 1991, accepted 21 August 1991

Two homologous series of mesogens viz p-chlorophenyl p'-n-alkoxycinna-mates¹ (I) and p-nitrophenyl p'-n-alkoxycinnamates' (II) have been synthesised. Three binary systems of the homologues of these series have been explored here The first two binary systems consist of homologues of series (1) ; binary system 1 consisting the homologues p-chlorophenyl p'-n-hexyloxycinnamate K 87° S 118° N 124° IA and p-chlorophen)I p'-n-decyloxycinnamate, K 78° S 123° IB and binary system 2 consisting the homologues p-chlorophenyl p'-ethoxycinnamate K 135° IA and p-chlorophenyl, p'-n-butoxycinnamate K 98.5° S 108° N 122° IS. The binary system 3 consists of homologues of series'', II, viz. p-nitrophenyi p'-ethoxycinnamate K 168° IA and p-nitrophenyl to-n butoxycinnamate K 116° N 120.5° IB In binary system 1, the overall mixed smectic characteristic predominates over a wide range of temperature and concentration The mixed nematic phase does not extend beyond above 30 mole% of the smectic mesogen (B). The N-I and S-I curves deviate very little from the rule of linearity. Contrary to which the binary system 2 indicates predominance of the mixed nematic character, the N-1 curve follows an ideal pattern The S-N curve shows the steep rising tendency as the concentration of the nematogen (B) increases similar to one found in the case of pure homologous series exihibiting polymesomorpbism^1,2. The binary system 3 presents similarity with other binary systems studied², the characteristic effects due to the magnitude of the dipole moments of the NO₂ group are discernible. The N-I curve deviates from the rule of linearity though the components comprising the system are identical in all respects in their molecular geometry.