Side-chain liquid-crystalline poly(ketone)s: effect of spacer length, mesogen type and mesogen density on mesomorphic behavior

Novel side-chain liquid-crystalline copolymers (SCLCPs) were synthesized vi a the Pd(II) catalyzed alternating copolymerization of mesogenic 1-alkenes and carbon monoxide. For methoxybiphenyl mesogens, these copolymers exhibit ed highly ordered smectic E mesophases and high glass transition temperatur es. The transition temperatures of these polymers were tuned by altering th e spacer length or by dilution of mesogen-containing alkenes with 1-hexene. Polymers with cyanobiphenyl or methoxyazobenzene mesogens exhibited nemati c mesophases. These polymers were the first ever nitrogen containing copoly mers of this type. Increase of the spacer length or the 1-hexene content of methoxybiphenyl-containing copolymers resulted in a decrease of the surfac e polarity of spincoated films. The decomposition temperature of these SCLC Ps started far above the isotropization temperature of the polymers.