TY - JOUR
T1 - Anisotropic dye adsorption and anhydrous proton conductivity in smectic liquid crystal networks
T2 - the role of cross-link density, order, and orientation
AU - Liang, T.
AU - Van Kuringen, H.P.C.
AU - Mulder, D.J.
AU - Tan, S.
AU - Wu, Y.
AU - Borneman, Z.
AU - Nijmeijer, K.
AU - Schenning, A.P.H.J.
PY - 2017/10/11
Y1 - 2017/10/11
N2 - In this work, the decisive role of rigidity, orientation, and order in the smectic liquid crystalline network on the anisotropic proton and adsorbent properties is reported. The rigidity in the hydrogen-bonded polymer network has been altered by changing the cross-link density, the order by using different mesophases (smectic, nematic, and isotropic phases), whereas the orientation of the mesogens was controlled by alignment layers. Adding more cross-linkers improved the integrity of the polymer films. For the proton conduction, an optimum was found in the amount of cross-linker and the smectic organization results in the highest anhydrous proton conduction. The polymer films show anisotropic proton conductivity with a 54 times higher conductivity in the direction perpendicular to the molecular director. After a base treatment of the smectic liquid crystalline network, a nanoporous polymer film is obtained that also shows anisotropic adsorption of dye molecules and again straight smectic pores are favored over disordered pores in nematic and isotropic networks. The highly cross-linked films show size-selective adsorption of dyes. Low cross-linked materials do not show this difference due to swelling, which decreases the order and creates openings in the two-dimensional polymer layers. The latter is, however, beneficial for fast adsorption kinetics.
AB - In this work, the decisive role of rigidity, orientation, and order in the smectic liquid crystalline network on the anisotropic proton and adsorbent properties is reported. The rigidity in the hydrogen-bonded polymer network has been altered by changing the cross-link density, the order by using different mesophases (smectic, nematic, and isotropic phases), whereas the orientation of the mesogens was controlled by alignment layers. Adding more cross-linkers improved the integrity of the polymer films. For the proton conduction, an optimum was found in the amount of cross-linker and the smectic organization results in the highest anhydrous proton conduction. The polymer films show anisotropic proton conductivity with a 54 times higher conductivity in the direction perpendicular to the molecular director. After a base treatment of the smectic liquid crystalline network, a nanoporous polymer film is obtained that also shows anisotropic adsorption of dye molecules and again straight smectic pores are favored over disordered pores in nematic and isotropic networks. The highly cross-linked films show size-selective adsorption of dyes. Low cross-linked materials do not show this difference due to swelling, which decreases the order and creates openings in the two-dimensional polymer layers. The latter is, however, beneficial for fast adsorption kinetics.
KW - adsorption
KW - liquid crystalline networks
KW - nanoporous polymers
KW - proton conduction
KW - smectic liquid crystals
UR - http://www.scopus.com/inward/record.url?scp=85031310335&partnerID=8YFLogxK
U2 - 10.1021/acsami.7b09386
DO - 10.1021/acsami.7b09386
M3 - Article
C2 - 28936867
AN - SCOPUS:85031310335
SN - 1944-8244
VL - 9
SP - 35218
EP - 35225
JO - ACS Applied Materials & Interfaces
JF - ACS Applied Materials & Interfaces
IS - 40
ER -