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Synthesis and characterization of novel ferroelectric liquid crystal polysiloxanes containing undecanoyloxy spacer (II)
Author(s) -
Zhang Qizhen,
Xue Qingbin,
Yang Kongzhang
Publication year - 1996
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/(sici)1099-1581(199602)7:2<135::aid-pat460>3.0.co;2-1
Subject(s) - mesogen , materials science , liquid crystal , moiety , differential scanning calorimetry , monomer , polymer , crystallography , thermal stability , biphenyl , polymer chemistry , side chain , organic chemistry , chemistry , liquid crystalline , composite material , optoelectronics , physics , thermodynamics
The synthesis of two novel side‐chain liquid crystal polysiloxanes (IP and IIP) containing 4‐[(s)‐2‐methyl‐butoxy] biphenyl or 4‐[(s)‐2‐methyl‐butoxy] biphenyl benzoate moiety as mesogenic units, respectively, and an aliphatic spacer containing undecanoyloxy units is presented. Differential scanning calorimetry, polarizing microscopy and X‐ray diffraction measurements revealed chiral smectic mesomorphism for the two polymers. Both polysiloxanes IP and IIP exhibit smectic A and chiral smectic C * phases. Among the corresponding monomers prepared in this study, the 4‐[(s)‐2‐methyl‐butoxy]biphenyl 10‐undecylen‐1‐ate shows smectic A and chiral smectic C * phases, but the 4‐[(s)‐2‐methyl‐butoxy] biphenyl 4‐(10‐undecylen‐1‐yloxy) benzoate reveals only smectic B, smectic A and cholesteric phases. The results seem to demonstrate that the tendency toward glass, and also that melting temperature (T m ) and isotropic temperatures (T i ) of liquid crystal, mesomorphic ranges (ΔT) and thermal stability in both polymers and monomers increase with increasing the rigidity or the number of the benzene ring or length versus diameter value of mesogenic moieties (L/D) value of mesogenic moieties. The T i and ΔT of polysiloxanes containing the undecanoyloxy spacer are lower than those containing the undecyloxy spacer on using the same mesogenic moiety. Polymerization generated a smectic phase and led to higher liquid crystal and isotropic transition temperatures; also the liquid crystal ranges were broadened and more ordered phases were formed comparing polymers with monomers, respectively.