Liquid-Crystalline Polymethacrylates by Atom-Transfer Radical Polymerization at Ambient Temperature

Side-on and side-end liquid-crystalline (LC) polymethacrylates were synthesized by atom-transfer radical polymerization at 20°C using monofunctional and difunctional initiators. The polymers have narrow molecular-weight distributions (M̄w /M̄n = 1.15–1.45). The polymerization kinetics were determined for a side-on LC methacrylate, and appear to be first-order, whatever the initiator used. However, the measured molecular weight is much larger than expected, probably because the initiation step is slow. The thermotropic properties of the LC polymers were studied by thermal optical polarizing microscopy, differential scanning calorimetry, and X-ray diffraction. For a side-end LC polymethacrylate, two LC phases were detected although only one has been reported in the literature. The phase sequence was shown to be Cr–SmA–N–Iso.