Structural study of liquid crystalline long-chain n-alkylammonium polyacrylates

A series of alkyl and dialkylammonium polyacrylates were synthesized by neutralizing a 5000 molecular weight poly(acrylic acid) with alkyl-end dialkylamines. Their thermal stability was investigated using thermogravimetry. Their thermotropic liquid crystal behavior was analyzed using differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. The dodecyl, didodecyl, and tetradecyl derivatives exhibited a smectic A phase in the whole range of temperatures explored, from ambient to thermal degradation. The hexadecyl, octadecyl, and dioctadecyl derivatives exhibited a smectic A phase at high temperatures and an ordered smectic B or E phase at low temperatures. Structures and structural parameters are briefly discussed.