Side-Chain Liquid Crystalline Polyacetylenes with Increasing Length of Alkyl Tails: From Highly Ordered Smectic to Smectic C Phase

摘要: Phase structures and transitions of a series side-chain liquid crystalline polyacetylene (SCLCPA) with short spacer three methylene units different lengths alkyl tails, namely, poly(5-{[(4′-alkyl-4-biphenylyl)carbonyl]oxy}-1-pentyne) (P-3,m, m is the number carbon atoms in tail, = 5, 7, 9, 11), were investigated using differential scanning calorimeter, polarized light microscopy, one- two-dimensional wide-angle X-ray diffraction. With spacer, P-3,m possesses mesogenic groups on side chain backbone coupled together thus renders sheetlike shape width nearly twice extended length. Experimental results reveal that (LC) structure strongly dependent tail length, from other SCLCPAs. For < 11, several layers molecules stack to form smectic A (SmA) block, molecular increases wi...