Confining Liquid Crystals to Nanoporous Molecular Sieves

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National Institute of Materials
Physics Bucharest-Magurele Romania
Confining Liquid Crystals to Nanoporous
Molecular Sieves by Ligia
Frunza NIMP, Bucharest -
Magurele Bucharest, January 27 2004
L. Frunza
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Outline

• Introduction
• confining effects
• aim of the investigations
• Experimental
• materials (molecular sieves confining
  organics)
• methods of investigation
• Results dielectric spectroscopy
• DSC, DTA, TG
• FTIR
• optical microscopy/CCV
• Co-operations bilateral
• FP6
• resources to collaborate

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• Introduction

Confining effects
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• Introduction
• Aim of the investigations

• Molecular sieves Nanoporous materials offering
  arrays of pores and cavities with known
  geometry
• Substitution in their framework may lead to a
  variety of guest- host interactions
• New structures are continuously synthesized

• Confined matter liquid crystals
• different other organics

• Studies aimed to investigate
• influence of the confinement on
• phase transitions (LC behavior)
• thermal stabilization
• anchoring mode of the molecules at the surface of
  the molecular sieves
• location of the organic molecules in the loaded
  samples
• inside the pores and/or cavities
• on the outer surface of the grains / agglomerates

• Potential applications of composites based on
  molecular sieves
• microlasers, sensors, biology (by
  functionalization), catalysts

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• Experimental
• Molecular sieves. AlMCM-41, AlSBA-15, SiNMS-F

Synthesis NIMP(INCDFM) partners

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• Experimental
• Confined matter

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• Experimental
• Investigation methods

• IR UV-vis spectroscopy in situ
• Broadband dielectric spectroscopy (partners)
• Thermal analysis (partners)
• differential thermal analysis (DTA)
• differential scanning calorimetry (DSC)
• Optical microscopy /CCV camera
• Luminescence / thermoluminescence
• Others
• thermogravimetry (partners)
• X-ray diffraction
• electron microscopy
• nitrogen absorption meas. (partners)

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• Results
• Confinement of liquid crystals

Bulk 8CB
A.Schoenhals, H.-L.Zubowa, R.Fricke, S.Frunza,
L.Frunza, R.Moldovan, Cryst. Res. Technol. 34,
1309 (1999)
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• Results
• Confinement of liquid crystals

Empty molecular sieves
L. Frunza, S. Frunza, A. Schönhals, et al., J.
Non-cryst. Solids, 307-310 (2002) 503. L.
Frunza, H. Kosslick, A. Schönhals, et al. ,
Proceedings SPIE-4799 (2002) 230. L. Frunza, S.
Frunza, A. Schönhals, et al., Stud. Surf. Sci.
Catal. 142 (2002) 1323.   L. Frunza, H. Kosslick,
S. Frunza, et al J. Phys. Chem B. 106 (2002)
9191.
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• Results
• Confinement of liquid crystals

Loaded molecular sieves

• Two relaxation processes may appear.
• The slow relaxation process is a new one, due to
  surface layer. Its temperature dependence follows
  a VFT law.

S.Frunza, A.Schönhals, L.Frunza, et al.,
Chem.Phys. Lett.307 (1999) 167. S. Frunza, L.
Frunza, A. Schönhals, J. Phys. IV France, 10
(2000) , Pr7-115. S. Frunza, L. Frunza, M.
Tintaru, et al., Liq. Cryst. Accepted Jan. 2004
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• Results
• Thermal analysis

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• Results
• DSC

• Partially filled samples with low filling degree
  do not show phase transitions
• Completely filled samples
• A part of confined 8CB shows phase transitions
• Downward shift of te peak temperature
• C-SA phase transition has the biggest shift
• correlation between the depression of the
  crystallization temperature and the reciprocal
  diameter of the pores cannot be established
• Most of the confined 8CB does not show any phase
  transitions

S. Frunza, L. Frunza, A. Schönhals, et al.,
Europhys. Lett. 56 (2001) 801.   L. Frunza, S.
Frunza, A. Schönhals, et al., Stud. Surf. Sci.
Catal. 142 (2002) 1323.    S. Frunza, H.
Kosslick, A. Schönhals, et al., J. Noncryst.
Solids 325 (2003) 103.
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• Results
• In situ FTIR spectroscopy

CN vibration is described as a vibration of a
localized group Species Bulk-like LC (2226
cm-1) Randomized state (ca. 2230 m-1)
Hydrogen bonded (2241 cm 1)
L. Frunza, S. Frunza, A. Schönhals, et al.,
J.Molec. Struct. 563-564, 491-495 (2001). L.
Frunza, H. Kosslick , U. Bentrup, et al., J.
Molec. Str. 651-653 (2003) 341-347. L. Frunza, S.
Frunza, I. Enache, et al., Mol. Cryst. Liq.
Cryst. Accepted September 2003.
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• Results
• Confinement of Jacobsen complex

L. Frunza, H. Kosslick , H. Landmesser, et al.,
J.Mol.Catal.123, 179-187 (1997) L. Frunza, I.
Enache, I. Nicolaie, et al., BPU-5, Serbia,
August 2003. L. Frunza, I. Nicolaie, S. Frunza,
et al., ICC, Paris, France , July 2004.
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• Results
• Lyotropic liquid crystals

Confinement is constructed during synthesis of
nanopores
Some results on studies concerning lyotropic
micelles are given in a Poster of T. Beica, R.
Moldovan, M. Tintaru I. Zgura, S. Frunza
T. Beica, R. Moldovan, M.R. Puica, S. Frunza,
Liq. Cryst. 29 (2002) 1275. T. Beica, R.
Moldovan, Irina Zgura, et al., BPU5, August
25-29, 2003, Serbia T. Beica, R. Moldovan, M.
Tintaru, et al., Liq. Cryst. Accepted Dec. 2003
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Bilateral scientific agreements Germany, Berlin
ACA Hendrik Kosslick Rolf
Fricke Ursula Bentrup Irene
Pitsch H.-L. Zubowa BAM Andreas
Schoenhals
COORDINATION ACTION CONCORDE - Co-ordination
of Nanostructured Catalytic Oxides Research
and Development in Europe Framework Programme
FP6 Priority 3 Nanotechnology and
nanosciences, knowledge-based multifunctional
materials, new production processes and
devices
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Team of Liquid Crystals and Surface Interactions
(NIMP) Stefan Frunza Ligia Frunza Traian
Beica Mihaela Tintaru Irina Zgura Irina
Nicolaie Rodica Moldovan
Organizers of the National Seminar of
Nanoscience and Nanotechnology Bucharest 2004
L. Frunza