TY - JOUR
T1 - The effect of a lateral alkyloxy chain on the ferroelectric nematic phase
AU - Cruickshank, Ewan
AU - Walker, Rebecca
AU - Storey, John M.D.
AU - Imrie, Corrie T.
N1 - Funding Information:
C.T.I. and J.M.D.S. acknowledge the financial support of the Engineering and Physical Sciences Research Council [EP/V048775/1].
PY - 2022/10/14
Y1 - 2022/10/14
N2 - The synthesis and characterisation of two series of low molar mass liquid crystals, the 4-[(4-nitrophenoxy)carbonyl]phenyl 2-alkoxy-4-methoxybenzoates (series 5-m) and the 4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 2-alkoxy-4-methoxybenzoates (series 6-m) are reported in order to explore the effects of a lateral alkyloxy chain on the formation and stability of the recently discovered ferroelectric nematic phase. In both series m, the number of carbon atoms in the lateral chain, is varied from one to nine. The two series differ by the addition of a fluorine substituent in the 6-m series. 5-1 is the extensively studied ferroelectric nematogen RM734. All the members of the 5-m series exhibited both a conventional nematic, N, and ferroelectric nematic, NF, phase, whereas all the members of the 6-m series exhibit a direct NF-I transition with the exception of 6-1 that also exhibits a N phase. The replacement of a hydrogen atom by a fluorine atom reduces the nematic-isotropic transition temperature, TNI, whereas the ferroelectric nematic-nematic, or isotropic, transition temperature, TNFN/I, increases. This is interpreted in terms of the reduced structural anisotropy associated with the larger fluorine atom whereas the increase in the stability of the NF phase reflects changes in polarity and polarizability. The dependence of TNI and TNFN/I on m in both series is similar, and these initially decrease on increasing m but converge to limiting values on further increasing m. This suggests that the lateral alkyloxy chain may adopt conformations in which it lies along the major axis of the mesogenic unit.
AB - The synthesis and characterisation of two series of low molar mass liquid crystals, the 4-[(4-nitrophenoxy)carbonyl]phenyl 2-alkoxy-4-methoxybenzoates (series 5-m) and the 4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 2-alkoxy-4-methoxybenzoates (series 6-m) are reported in order to explore the effects of a lateral alkyloxy chain on the formation and stability of the recently discovered ferroelectric nematic phase. In both series m, the number of carbon atoms in the lateral chain, is varied from one to nine. The two series differ by the addition of a fluorine substituent in the 6-m series. 5-1 is the extensively studied ferroelectric nematogen RM734. All the members of the 5-m series exhibited both a conventional nematic, N, and ferroelectric nematic, NF, phase, whereas all the members of the 6-m series exhibit a direct NF-I transition with the exception of 6-1 that also exhibits a N phase. The replacement of a hydrogen atom by a fluorine atom reduces the nematic-isotropic transition temperature, TNI, whereas the ferroelectric nematic-nematic, or isotropic, transition temperature, TNFN/I, increases. This is interpreted in terms of the reduced structural anisotropy associated with the larger fluorine atom whereas the increase in the stability of the NF phase reflects changes in polarity and polarizability. The dependence of TNI and TNFN/I on m in both series is similar, and these initially decrease on increasing m but converge to limiting values on further increasing m. This suggests that the lateral alkyloxy chain may adopt conformations in which it lies along the major axis of the mesogenic unit.
UR - http://www.scopus.com/inward/record.url?scp=85141899427&partnerID=8YFLogxK
U2 - 10.1039/d2ra05628c
DO - 10.1039/d2ra05628c
M3 - Article
AN - SCOPUS:85141899427
VL - 12
SP - 29482
EP - 29490
JO - RSC Advances
JF - RSC Advances
SN - 2046-2069
IS - 45
ER -