PMID- 30065982
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20181005
LR  - 20181005
IS  - 1744-6848 (Electronic)
IS  - 1744-683X (Linking)
VI  - 14
IP  - 37
DP  - 2018 Sep 26
TI  - Engineering the anchoring behavior of nematic liquid crystals on a solid surface 
      by varying the density of liquid crystalline polymer brushes.
PG  - 7569-7577
LID - 10.1039/c8sm00991k [doi]
AB  - Controlling the orientation of liquid crystal (LC) molecules towards contacting 
      surfaces is a crucial requirement for the development of LC displays and passive 
      electro-optical devices. Up to now, research has been focused on photo-responses 
      of a LC azobenzene polymer system to obtain either planar or homeotropic 
      orientation of LCs. It remains a challenge, however, to tune the polar angle of 
      LC molecules on the solid surface and gain more insights about the polymer chain 
      conformation extending in LC medium. Here, we deposit a liquid crystalline side 
      chain polymer brush, poly(6-(4-methoxy-azobenzene-4'-oxy)hexyl methacrylate) 
      (PMMAZO), onto the solid surface with film thickness varying between  approximately 3 nm and 13 
      nm; therefore, the grafting density of the brush layer ranges from 0.0219 to 
      0.0924 chains per nm2. When LCs are confined in hybrid cells with a top surface 
      eliciting uniform homeotropic anchoring and a bottom surface covered by the 
      PMMAZO brush, the out-of-plane polar angle of 4-pentyl-4'-cyanobiphenyl (5CB) on 
      the brush layer gradually changes from  approximately 0 degrees  to  approximately 62 degrees  by simply increasing the 
      grafting brush density. The surface forces apparatus (SFA) measurement is used to 
      determine 5CB as a good solvent for the PMMAZO brush and understand the 
      relationship between the chain conformation in 5CB and the anchoring behavior of 
      LC molecules on the polymer brush layer. For high grafting density, the polymer 
      chain in 5CB extends significantly away from the substrate, making the side chain 
      mesogens on average almost parallel to the substrate; for the low-density case, 
      the main chain extends in the narrow region around the surface for aligning the 
      mesogens perpendicular to the substrate.
FAU - Li, Xiao
AU  - Li X
AD  - Institute for Molecular Engineering, University of Chicago, Chicago, USA. 
      nealey@uchicago.edu.
FAU - Yanagimachi, Takuya
AU  - Yanagimachi T
FAU - Bishop, Camille
AU  - Bishop C
FAU - Smith, Coleman
AU  - Smith C
FAU - Dolejsi, Moshe
AU  - Dolejsi M
FAU - Xie, Helou
AU  - Xie H
FAU - Kurihara, Kazue
AU  - Kurihara K
FAU - Nealey, Paul F
AU  - Nealey PF
LA  - eng
PT  - Journal Article
PL  - England
TA  - Soft Matter
JT  - Soft matter
JID - 101295070
EDAT- 2018/08/02 06:00
MHDA- 2018/08/02 06:01
CRDT- 2018/08/02 06:00
PHST- 2018/08/02 06:00 [pubmed]
PHST- 2018/08/02 06:01 [medline]
PHST- 2018/08/02 06:00 [entrez]
AID - 10.1039/c8sm00991k [doi]
PST - ppublish
SO  - Soft Matter. 2018 Sep 26;14(37):7569-7577. doi: 10.1039/c8sm00991k.