PMID- 36932484
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20230320
LR  - 20230320
IS  - 2470-0053 (Electronic)
IS  - 2470-0045 (Linking)
VI  - 107
IP  - 2-1
DP  - 2023 Feb
TI  - High-resolution dielectric anisotropy investigation of carbon nanotube-smectic-A 
      liquid crystal dispersions: An upper limit of the latent heat and the 
      pretransitional anomaly at the nematic-smectic-A transition.
PG  - 024702
LID - 10.1103/PhysRevE.107.024702 [doi]
AB  - Within the entire mesomorphic range, high-precision dielectric anisotropy data 
      with the high-temperature resolution is presented for a highly polar smectic-A 
      liquid crystal 8CB (octylcyanobiphenyl) as well as 8CB nanocomposites doped with 
      both pristine multi-walled carbon nanotubes (p-MWCNTs) and carboxyl group (-COOH) 
      functionalized MWCNTs (f-MWCNTs). The temperature variation of the nematic order 
      parameter across both the nematic-isotropic (N-I) and the nematic-smectic-A 
      (N-Sm-A) phase transitions of the neat 8CB and 8CB+MWCNT nanocomposites has then 
      been derived from the dielectric anisotropy data within the framework of the 
      Maier-Meier theory. With the inclusion of MWCNTs, both the N-I and the N-Sm-A 
      transition temperatures have been noted to shift to lower temperatures as 
      compared to the 8CB host. Also, for all 8CB+MWCNT nanocomposites, regardless of 
      the surface functionalization, it has been well documented that the N-I 
      transition is weakly first order, whereas the N-Sm-A transition remains 
      continuous within the experimental resolution. For all investigated samples, the 
      temperature dependence of the nematic order parameter has been shown to be 
      quasitricritical, within the experimental resolution. From the attentive 
      inspection of the dielectric anisotropy data in the vicinity of the N-Sm-A 
      transition, the upper limits for a possible latent heat DeltaH_NA for the 8CB host 
      and all 8CB+MWCNT composites, for the first time, have been derived. The 
      so-derived DeltaH_NA values for all investigated samples have also been compared 
      with those extracted from the optical birefringence data, and an excellent 
      consistency has then been noted. The N-Sm-A pretransitional anomaly has been 
      investigated and the effective specific heat capacity exponent alpha values have been 
      yielded from the power-law analysis of our high-resolution Deltavarepsilon(T) data across the 
      N-Sm-A transition for all investigated samples. It has been well documented that 
      the incorporation of MWCNTs to the 8CB host leaves the N-Sm-A transition 
      essentially bulklike. We discussed that, to some extent, the compliance of MWCNTs 
      does not drive the N-Sm-A transition to 3D-XY-like behavior, that is the strength 
      of de Gennes coupling will remain the same for all nanocomposites. This issue can 
      be ascribed to the weaker nature of MWCNT disorder. In this work, for the first 
      time, high-resolution Deltavarepsilon(T) data has been shown to be very adequate and offer an 
      easy way to investigate the N-Sm-A transition as compared to calorimetric 
      methods.
FAU - Guven, Funda
AU  - Guven F
AD  - Department of Physics, Istanbul Technical University 34469 Maslak, Istanbul, 
      Turkey.
FAU - Girgin, Ozgun
AU  - Girgin O
AD  - Department of Physics, Istanbul Technical University 34469 Maslak, Istanbul, 
      Turkey.
FAU - Cetinkaya, Mehmet Can
AU  - Cetinkaya MC
AD  - Department of Physics, Istanbul Technical University 34469 Maslak, Istanbul, 
      Turkey.
FAU - Ozbek, Haluk
AU  - Ozbek H
AD  - Department of Physics, Istanbul Technical University 34469 Maslak, Istanbul, 
      Turkey.
FAU - Yildiz, Sevtap
AU  - Yildiz S
AD  - Department of Physics, Istanbul Technical University 34469 Maslak, Istanbul, 
      Turkey.
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Phys Rev E
JT  - Physical review. E
JID - 101676019
SB  - IM
EDAT- 2023/03/19 06:00
MHDA- 2023/03/19 06:01
CRDT- 2023/03/18 01:00
PHST- 2022/10/12 00:00 [received]
PHST- 2023/02/01 00:00 [accepted]
PHST- 2023/03/18 01:00 [entrez]
PHST- 2023/03/19 06:00 [pubmed]
PHST- 2023/03/19 06:01 [medline]
AID - 10.1103/PhysRevE.107.024702 [doi]
PST - ppublish
SO  - Phys Rev E. 2023 Feb;107(2-1):024702. doi: 10.1103/PhysRevE.107.024702.