Julien Schmitt, postdoc in the Physical Chemistry department. Internship 2010: Study of the SAXS scattering pattern of mesoporous materials

Transcription

1 Before starting Julien Schmitt, postdoc in the Physical Chemistry department Internship 2010: Study of the SAXS scattering pattern of mesoporous materials PhD : Self-assembly mechanism of mesoporous materials Postdoc 2014-onwards: From mesoporous materials towards the formation of an artificial nacre

2 Mesoporous materials Julien Schmitt Physical Chemistry

3 Outline: 1/ Introduction to porous materials characteristics and applications 2/ Synthesis strategy of porous materials how and why study the formation mechanism 3/ Current research towards the formation of an artificial nacre

4 1/porous materials, characterisation and applications INTRODUCTION

5 A huge variety of porous materials! In nature

6 Zeolites naturally occurring crystalline aluminosilicates Axel Fredric Cronstedt, 1756, stilbite Microporosity <2nm Synthesized Zeolites more than 200 structures Si/Al ratio, cations pores size and connectivity Cristalline walls

7 Silica gels A silica source: CH 2 CH 3 O TEOS = CH 2 CH 3 O Si O CH 2 CH 3 O CH 2 CH 3 In water hydrolysis condensation O OH Si O O Si O O O O Si O Si O Si OH O O O Michaux, PhD manuscript Silica clusters

8 IUPAC classification Microporous: Mesoporous: Macroporous: < 2nm 2-50nm > 50nm How to ally the properties of a «large» porosity with an organisation of the pores?

9 Mesoporous materials Kresge et al, Nature 1992

10 Mesoporous materials Pores with diameters 2-50 nm High surface area ~ m 2 /g Ordered or disordered structures (but amorphous) Various chemical compositions Organic materials function as structure promoters

11 Huge surface area: 1000 m 2 /g How to study the pores organisation and size of these materials?

12 Small Angle X Ray Scattering Ewald sphere detector Incident beam 1/ k r sample 2 1 d 10 nm D 1 m Small angles «big» objects I( q) A P( q) S( q) Form factor (type of objects in solution) Structure factor (interactions)

13 X-ray diffraction gives fingerprint of the structure Small angle region! Bragg s law

14 Pioneering work ( ): M41S - materials 1 MCM-41-2D hexagonal MCM-48 - cubic(ia3d) MCM-50 - lamellar MCM-41 MCM-48 FSM - materials 2 2 D hexagonal MCM Kresge, Leonowicz, Roth, Vartuli, Beck. Nature 359 (1992) 710, 2. Inagaki, Fukushima, Kuroda J. Chem. Soc. Chem. Commun. (1993) 680

15 Transmission Electron Microscopy Transmission electron microscopy gives direct images structures can be determined

16 Scanning Electron Microscopy Study the morphology of the grains Kjellman et al. Chem Mater 2013

17 Nitrogen sorption Nitrogen sorption gives information on pore geometry, pore size and surface area.

18 Applications Heterogenous catalysis: carrier for catalysts Nanoparticles synthesis Drug delivery Argyo et al. Chem Mater 2014 Bleuzen et al. Chem Comm 2010

19 how and why study the formation mechanism STRATEGY TO SYNTHESIZE POROUS MATERIALS

20 How are porous materials constructed? A hint: This image is NOT realistic! Astérix, la Serpe d Or, 1960

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22 Building materials using templates Put stones around the template

23 Building completed - remove the template

24 Molecular building Stones silica molecules Templates molecules that can be removed

25 Cement covalent bonds

26 Pores templated by single molecules Zeolites Synthesis in aqueous solution template + silica precursor Example of templates: cation molecules Removal of template - porous materials (still microporous!)

27 Template Single molecule template Kresge et al 1992 Inagaki et al 1992

28 Amphiphiles Hydrophilic head Hydrophobic tail

29 Supramolecular (Micellar aggregates) template

30 Long range organisations - mesophases

31 1) Cationic (Mobil, Kuroda) Classic MCM-41, MCM-48, MCM-50, FSM-structures Hydrophilic Hydrophobic Cethyltrimethyl ammouniumchloride + TEOS (kanemite) basic conditions

32 2.) Non-ionic block copolymer - Pluronic polymer SBA-15 (EO) x -(PO) y -(EO) x hydrophilic hydrophilic hydrophobic

33 As-synthesised, composite Template removed, porous Silica source in water: hydrolysis/condensation In presence of surfactant!

34 SBA-15 SiO 2 2D hexagonal Surfactant: P123 Silica source: TEOS Mesostructured Repeat 10nm amorphous

35 A simple synthesis bricks +? TMOS /TEOS surfactant solution + silica precursor Hybrid mesophase formation Hybrid material (hydrothermal treatment) Surfactant removal Mesoporous material Why are the micelles ordered?

36 Understand the formation (sequence of events, intermolecular Interactions). Control properties rational design.

37 Micelles are ordered prior to the silica precursor addition?

38 A typical synthesis Synthesis - 24h (T = RT C) Hydrothermal treatment 24h (T= C) Calcination (T 500 C) removal of the structure director Mix between a surfactant solution at 2,5 wt% + silica source

39 Long range organisations - mesophases

40 Cooperative Template Mechanism +? TMOS /TEOS surfactant solution + silica precursor cooperative mechanism Hybrid mesophase formation Hybrid material (hydrothermal treatment) Surfactant removal Mesoporous material

41 In-situ experiments to follow the synthesis SAXS/SAXD Small angle x-ray scattering/diffraction USAXS Ultra small angle x-ray scattering Cryo-TEM European Synchrotron Radiation Facility ESRF, Grenoble, France

42 In-situ SAXS/USAXS

43 In-situ SAXS/USAXS

44 4 SBA-15 : synthesis SAXS :SOLEIL SWING beamline data modelling via several models Manet, Schmitt et al, J. Phys Chem B, 2011

45 I (cm -1 ) SBA-15: mechanism of formation without TEOS t = 1 min t = 10 min 0.01 q q (Å -1 ) No TEOS t = 1 min t = 10 min 4

46 I (cm -1 ) SBA-15: mechanism of formation without TEOS t = 1 min t = 10 min 0.01 q q (Å -1 ) No TEOS t = 1 min t = 10 min q -1 t = 18 min t = 18 min 1

47 I (cm -1 ) SBA-15: mechanism of formation without TEOS t = 1 min t = 10 min 0.01 q q (Å -1 ) No TEOS t = 1 min t = 10 min q -1 t = 18 min t = 18 min t = 30 min q -1 t = 30 min 1

48 I (cm -1 ) SBA-15: mechanism of formation without TEOS t = 1 min t = 10 min 0.01 q q (Å -1 ) No TEOS t = 1 min t = 10 min q -1 t = 18 min t = 18 min t = 30 min t = 45 min t = 60 min q -1 t = 30 min t = 45 min q -4 t = 60 min 1

49 Control the morphology of the SEM grains 36 C 40 C 50 C 56 C TEM Moulin, Schmitt et al. Soft Matter., 2013

50 Material in shape of platelets D= 1 µm t=350 nm

51 Hierarchical materials TOWARDS THE FORMATION OF AN ARTIFICIAL NACRE

52 brick Creating innovative materials mortar Form a thermosensitive nacre structure

53 Silica/PNIPAM particles Make the particles fluorescent Polymerization of the PNIPAM shell

54 E

55 Formation layer by layer PNIPAM: drop deposition Silica: Langmuir-Blodgett

56 2 layers (1-1) 4 layers (2-2)

57 To be continued

58 The take away messages Read Astérix!! Ordored mesoporous materials: porosity controlled (2-50 nm of pores size, surface area ~ 1000 m²/g) Formed using surfactant as templates and an inorganic source Synthesis studied in SAXS, powerful tool for soft matter and material science