Mesophase behaviour of 1:1 mixtures of 4-n-alkoxyphenylazo benzoic acids bearing terminal alkoxy groups of different chain lengths

ABSTRACT

The thermal and mesophase behaviour of all possible 1:1 mixtures (In/Im) formed from any two homologues of 4-n-alkoxyphenylazo benzoic acids bearing different alkoxy chain lengths (n and m vary between 6 and 16 carbons), were investigated by differential scanning calorimetry (DSC) and phases identified by polarised light microscopy (PLM). Phase transitions were investigated as a function of the average alkoxy chain length (=(n + m)/2) of the mixed acids. A comparison, made between the present series and previously investigated simpler analogues, 4-n-alkoxy benzoic acids, revealed that increasing the length of the mesogenic core increased the stabilities of both the smectic C and nematic phases.

GRAPHICAL ABSTRACT

KEYWORDS:

• 4-n-alkoxyphenylazo benzoic acids
• 4-n-alkoxy benzoic acids
• binary mixtures
• phase transitions

Disclosure statement

No potential conflict of interest was reported by the authors.