First insights on experimental diol grafting and sheet exfoliation. Strasbourg 2017

1. Academic period
2016-2017
Diol grafting into an
Aurivillius phase and first
insights on the microwave
assisted exfoliation
ERASMUS INTERN : NIKOLOPOULOU MARIA
SUPERVISORS : M. ROGEZ GUILLAUME
M. PIERRE RABU
Université de Strasbourg Ecole de physique et de chimie-physique
Institute de Physique et Chimie de Matériaux de Strasbourg
(UMR 7504 CNRS-Unistra)

2. [1]
Remerciements
J’exprime mes profonds remerciements à mes directeurs de stage M. Guillaume Rogez et M.
Pierre Rabu. Aussi a Emilie Delahane, je voudrais exprimer ma gratitude, elle m’a aidée
beaucoup les premières jours. En outre, je tiens également à remercier le membre de notre
groupe Quentin Evrard et Oksana Toma et tous les autres stagiaires et l’autres membres du
DCMI pour leur aide et leur amitié. Travailler avec eux pendant ce temps sera mes bons
souvenirs.
Aussi il faut remercier et les personnes qui m’aident pour faire tous les mesures pour
chacarteriser mes resultats.
A la fin j’exprime mes profonds remerciements à ma famille en Grèce. Grace à votre soutien je
peux réaliser tous mes désirs dans ma vie.
Maria Nikolopoulou
13/06/2017

3. [2]
Layout
A. General ...............................................................................................................................4
B. Grafting of a diol into a layered perovskite........................................................................5
B.1. Introduction .....................................................................................................................5
B.1.1. Perovskite.....................................................................................................................5
B.1.2. Layered perovskites......................................................................................................5
B.1.3. Ion- exchange reactions................................................................................................7
B.1.4. Purpose of the project...................................................................................................7
B.2. Results and discussion.....................................................................................................7
B.2.1 Progress of experiments ................................................................................................7
B.2.2. Synthesis.......................................................................................................................8
B.2.2.1. Synthesis of BST.......................................................................................................8
B.2.2.2. Microwave-assisted synthesis of HST ......................................................................8
B.2.2.3. Microwave-assisted functionalization of HST by aliphatic amines-Synthesis .........8
B.2.2.4. Microwave-assisted functionalization of C2N-HST by 1,3-propanediol..................8
B.2.3. Characterization ...........................................................................................................8
B.2.3.1. XRD analysis.............................................................................................................8
B.2.3.2 Infrared spectroscopy ...............................................................................................10
B.2.3.3. Solid state NMR......................................................................................................11
B.2.3.4. SEM observation.....................................................................................................12
B.4. Conclusions ...................................................................................................................13
C. Microwave-assisted exfoliation of an Aurivillius phase..................................................14
C.1. Introduction ...................................................................................................................14
C.1.1. What is exfoliation .....................................................................................................14
C.1.2. Nanoarchitectures of colloidal suspension.................................................................14
C.1.3. Nanostructured materials............................................................................................15
C.1.4. Liquid phase exfoliation - until now ..........................................................................16
C.1.5. Our purpose................................................................................................................16
C.2.Results and discussion....................................................................................................16
C.2.1. Conditions of experiments and way of testing..........................................................16
C.2.2. Characterization .........................................................................................................17
C.2.2.1 Tyndall effect ...........................................................................................................17
C.2.2.2 AFM .........................................................................................................................17

4. [3]
C.2.3. Experiments of exfoliation.........................................................................................18
C.2.3.1 Observations.............................................................................................................19
C.2.4 Conclusions.................................................................................................................24
D.Annex ...............................................................................................................................25
D.1 Synthesis and characterization technics.........................................................................25
D.2 Synthesis ........................................................................................................................25
D.2.1 Starting materials ........................................................................................................25
D.2.2 Intercalation of mono n-alkylamines ..........................................................................26
D.2.3 Grafting of n-alcohols into C2N-HST .........................................................................26
E. References ........................................................................................................................27

5. [4]
A. General
This work is based on doctorate project of Yanhui Wang “Hybridation d’oxydes lamellaires:
de l’insertion a la synthése in situ”. This work is separated to two basic parts.
For the first part the purpose is to graft a diol, 1,3-propanediol (C3(OH)2), into a protonated
Aurivillius-phase Bi2SrTa2O9 (BST), using microwave irradiation. The question we want to
address here is whether both hydroxide functions are grafted, leading to a pillaring arrangement
of the molecule, or only one function, leading to a bilayer arrangement.
The second part is a first exploration to exfoliate already functionalized lamellar phases, based
on the same starting Aurivillius phase BST using microwave-assisted processes.

6. [5]
B. Grafting of a diol into a layered perovskite
B.1. Introduction
B.1.1. Perovskite
For many years, benefiting from the development of solid-state inorganic chemistry, various
perovskites and compounds possessing perovskite-related structures have been synthesized.
The simple perovskite can be expressed as ABX3, where A is a large electropositive cation, B
represents a transition metal cation and X is an anion. Since oxides are dominant, the formula
can also directly be expressed as ABO3.[1]
B.1.2. Layered perovskites
Lamellar systems are particularly tailored for the hybrid approach, due to the versatility of
insertion reactions which can be realized and the subsequent versatility of properties which
result. Among layered materials, layered perovskites and layered compounds with perovskite-
related structures remain a favorite subject of study in solid state chemistry and materials
science. They present interesting physical properties such as photovoltaic, photocatalytic,
photoelectrochemical activities and magnetic properties.
Among perovskite oxides, the layered ones are especially interesting for us for their further
functionalization. The variants with layered perovskite structure include mainly Dion-Jacobson,
Ruddlesden-Popper and Aurivillius phases.
Figure 1. presents the basic cubic perovskite structure. The B-site cation resides at the center
of octahedral sites surrounded by oxygen anions, and A-site cation resides at the center of
interstitial large cavity surrounded by 8 BO6 octahedrons. [9]
Ruddlesden-Popper (RP) phases
are a form of layered perovskite structure consist of two-dimensional perovskite slabs
interleaved with cations. The general formula of RP phase is An-1A’2BnX3n+1, where A, A’, and
B are cations, X is an anion and n is the number of the layers of octahedra in the perovskite-
like stack. Generally, it has a phase structure that results from the intergrowth of perovskite-
type and NaCl-type structures. [10]
The Dion-Jacobson phases have the general formula M+1
A(n-
1)BnO(3n+1). They differ from the other layered phases by having a layer of alkali metal as the
separating motif.[9]
Aurivillius phases are a form of perovskite represented by the general
formulae is (Bi2O2)(An−1BnO3n+1) where A is a large 12 co-ordinate cation, and B is a small 6
co-ordinate cation. Basically, their structure is built by alternating layers of [Bi2O2]2+
and
pseudo-perovskite blocks, with perovskite layers that are n octahedral layers in thickness. [2]

7. [6]
Figure 1. Representative structure of selected perovskites and layered perovskites. The
construction of the perovskite unit cell from the corner-sharing BO6 octahedron and the three
typical members of layered perovskites.
Various protonated forms of Aurivillius and other phases like Dion-Jacobson can react with
various organic molecules, which leads to the preparation of various organic-inorganic hybrids
based on perovskite structures either by intercalation or by grafting reactions. Generally, the
mechanisms of intercalation of layered perovskites have been accepted as acid-base reactions.
The grafting reactions with organic molecules, to put hybrids based on layered perovskites
possess covalent bonds between organic phases and inorganic ones.
Figure 2. Nowadays, the functionalization of ion-exchangeable layered perovskite, based on
the soft chemistry routes, has considerably developed: ion-exchange, insertion, grafting and
exfoliation.
Figure 2. Common soft chemistry approaches to the functionalization of layered perovskites.
[1]

8. [7]
B.1.3. Ion- exchange reactions
Ion-exchange reactions, as simple low-temperature methods, have been widely used. This is
due to the existence of various cations of cationic units in the interlayer space of the types of
layered perovskites. Acid treatments of layered perovskites, which can be taken as cationic
exchange reactions between proton and interlayer cations or other structural units, have an
extremely great importance, because the obtained protonated phases not only retain the
corresponding layered perovskite structure but also become reactive with some kinds of organic
molecules, which opens the door to prepare various inorganic-organic hybrids exhibiting
various properties and can be utilized as hosts for various functional materials. [1]
B.1.4. Purpose of the project
Microwave assisted reactions have essentially been used in organic chemistry, but also in
coordination chemistry and in materials chemistry. It has been also used in post-
functionalization of nanoparticles or layered simple hydroxides. Microwave activation has
proved to be particularly useful to accelerate reactions to increase the yields and the purity of
compounds under milder reaction conditions and to obtain new products. So, additional
advantages of microwave irradiation are also the decrease of the reaction time and the no loss
on conversion rates.
Functionalization of ion-exchangeable layered perovskites by intercalation of organic
compounds has been widely described in the literature. Such functionalization process involves
first the transformation of the layered perovskites into their protonated forms. For Aurivillius
phases, this initial transformation involves the selective leaching of the bismuth oxide layers.
Then the protonated layered perovskites can be functionalized by amines, via cation exchange
or acid-base reaction. For this project, using the knowledge of Yanhui’s thesis[1]
, that means we
know how a factionalized surface react by grafting of alcohols and amines. Here we use
microwave irradiation, to protonate the BST to obtain the protonated form H2Bi0.1Sr0.85Ta2O7
(HST) and it is subsequent functionalization by various amines. HST is not suitable to do a graft
directly with a bulky alcohol, but only if there is an alkylamine to replace it. We have to graft
the diol 1,3-propanediol into the functionalized Aurivillius phase and to characterize how it is
happen by pillaring arrangement of the molecule, or only one function, leading to a bilayer
arrangement.
B.2. Results and discussion
B.2.1 Progress of experiments
Here we use microwave irradiation, to protonate the BST to obtain the protonated form
H2Bi0.1Sr0.85Ta2O7 (HST) and it is subsequent functionalization by various amines. After using
one more time microwave irradiation to functionalize the HST with two of the aliphatic amines
(C2N & C4N), because as it is written on Yanhui thesis to get a grafted alcohol firstly we should
insert an amine group to the factionalized material. Last step, using again microwave irradiation
we insert 1,3-propanediol and after we realize all the tests to characterize the new powder. The
purpose of this work is to understand, comparing the results from the bibliography and
Yanhui’s results, what exactly happen in the reaction. There are two possible hypotheses, the
first is only one side of 1,3-propanediol grafted to the perovskite-like slab, and the second is
and the two sides of 1,3-propanediol to be grafted.

9. [8]
B.2.2. Synthesis
B.2.2.1. Synthesis of BST
BST was synthesized according to published procedure as it is written in Wanhui thesis [2]. It
is a solid reaction and the longer time of grinding is proposed to get a better crystallized
material.
B.2.2.2. Microwave-assisted synthesis of HST
HST was synthesized by acid treatment of the starting Aurivillius phase BST. The XRD pattern
of BST (figure 3.) can be indexed on the basis of an orthorhombic cell (a=0.5523(4) nm, b=
0.5519(4) nm, c=2.507(2) nm), in accordance with the reported powder patterns, and the
previously reported structure. We should note that if we put the cleaned HST powder in the
oven over the night we will get a better crystallized material, but the reactivity will be decreased
for the next step reaction. Using water for the washing four to five times is also part of a good
powder because we want to remove all the acid from the compound. It is important to note that
we try also the classical protonation method, but it wasn’t successful. Last but not least for our
experimental it is not so important to get the best crystallinity for the compound.
B.2.2.3. Microwave-assisted functionalization of HST by aliphatic amines-Synthesis
The insertion of mono-n-alkylamines (CnN-HST, n=2,4) was performed using two amines,
ethylamine and butylamine with respect to HST, in a THF/H2O mixture (4:1). About 4 to 5
times washes with water can make a better powder.
B.2.2.4. Microwave-assisted functionalization of C2N-HST by 1,3-propanediol
The insertion of a diol (1,3-propanediol) with respect to C2N-HST Using a stirring microwave
irradiation for 2 hours (fast reaction) and wash the powder two or three times with acetone, give
us the desirable result. It is important to be noticed that the 1,3-propanediol bottle must be
recently opened, otherwise it lost its reactivity.
B.2.3. Characterization
B.2.3.1. XRD analysis
Figure 3. shows the XRD patterns of BST and the reaction products until the creation of
C3(OH)2-HST. Until the creation of C2N-HST we get the same results as Yanhui. For example,
the size of HST in the 00l direction is reduced concerning the references in the bibliography
because of the use of microwave irradiation. For the C2N-HST, in the low 2θ range the XRD
patterns of the hybrid compounds show essentially series of intense (00l) reflections, which
evidence his lamellar structure. These (00l) reflections are shifted to lower angles with respect
to the ones of the starting product HST which are no longer present to lower angles compounds.
The interlayer distance (c parameter) can be determined from the (00l) reflection, for C2N-HST
c=1.57 nm which fits well the relation d (nm) = 1.24 + 0.19 nc. After reacting with C3(OH)2 the
interlayer distance increase.

10. [9]
10 20 30 40
Intensity(a.u.)
2 (°)
Figure 3. XRD pattern of the starting product BST (black) to HST (red) to C2N-HST (green)
to C3(OH)2-HST (blue).
Figure 4. Adding ours result to the results of Yanhui, the interlayer distance for 3 carbon atoms
in n-alcohol, we get the following figure. The adding point corresponds to n=3 (carbon atoms)
is our new experiment which aid to understand the behavior of this reaction. Clearly it shows a
linear relationship between the interlayer distance and the number of carbons in the aliphatic
chain of α,ω-alkanediols, for a number of carbon n=4,7,8,9,12. We can realize that for n=2,3
we obtain another linear relationship, that means for shorts alcohols the grafting is different
than for long alcohols.
2 4 6 8 10 12
1,4
1,6
1,8
2,0
2,2
2,4
interlayerdistance(nm)
number of carbon atoms
Figure 4. Relationship between the number of carbon atoms in the aliphatic chain of α,ω-
alkanediols and the interlayer distance of the corresponding grafted products (full line
corresponds to the best linear fit).

11. [10]
B.2.3.2 Infrared spectroscopy
The following figure, figure 5., shows the corresponding IR spectra of C3(OH)2-HST and 1,3-
propanediol. Also, the figure 6. is from Yanhui thesis and shows IR spectra of ethylene glycol,
1-4-butanediol, C2(OH)2-HST and C4(OH)2-HST. In both of the two figures the disappearance
of the signal of -CH3 group, which belongs to starting material C4N-HST, is clearly noticed.
This means the butylamine in the interlamellar space is completely removed.
To be more specific, for the figure 5. comparing with the spectrum of C3(OH)2-HST with that
of 1,3-propanediol, we can notice that there are strong absorptions at the same positions: 3300
cm-1
which belongs to -OH group and 1155 cm-1
(which looks shifted from the same position
of 1,3-propanediol) which belongs to C-OH group and also another signal 1078 cm-1
(almost
unchanged), indicates the appearance the existence of free -OH. The signal in 570 cm-1
shows
us the C-Ta-O and last but not least the signal in 2800 to 2950 cm-1
belongs to CH2.
For the figure 6. comparing with the spectrum of C2(OH)2-HST with that of ethylene glycol,
we can notice that there are strong absorptions at the same positions: 3296 cm-1
which belongs
to -OH group and 1086 cm-1
which belongs to C-O group, indicates the existence of free -OH
groups in the obtained hybrid C2(OH)2-HST. In addition, the appearance of new signal at 1149
cm-1
which is believed to come from the blue shift of C-O groups, indicates the formation of
covalent bond C-O-Ta between ethylene glycol and layered perovskite. On the contrary, the
spectrum of C4(OH)2-HST shows the disappearance of the signal of -OH (3290 cm-1
) which
respect to the spectrum of 1,4-butanediol, which strongly indicates the absence of -OH groups
in the obtained hybrid. In addition, there is a blue shift of 100 cm-1
of the C-O group, which
indicates the formation of covalent bond C-O-Ta between 1,4-butanediol and layered
perovskite. The above analyses (XRD and IR spectroscopy) strongly suggest that C3(OH)2-HST
presents a bilayer arrangement of the guest species, with only one side of 1,3-propanediol
grafted to the perovskite-like slap, the other OH group remaining free. This compound acts like
C2(OH)2-HST, on the other hand the C4(OH)2-HST presents a pillaring arrangement of guest
species with both sides of 1,4-butanediol grafted to the perovskite-like slab.
5001000150020002500300035004000
20
40
60
80
100
Transmittance(%)
Wavenumber (cm-1
)
Figure 5. IR spectra of C3(OH)2-HST (black) and 1,3-propanediol (red).

12. [11]
4000 3500 3000 2500 2000 1500 1000 500
C4
(OH)2
C2
(OH)2
C4
(OH)2
-HST
Transmittance(a.u.)
Energy (cm-1
)
C2
(OH)2
-HST
Figure 6. IR spectra of ethylene glycol, 1,4-butanediol, C2(OH)2-HST and C4(OH)2-HST.[1]
B.2.3.3. Solid state NMR
In order to check the above hypothesis, solid state NMR spectroscopy was employed
(collaboration Fabrice Leroux, Institut de Chimie de Clermont-Ferrand). For C3(OH)2-HST
three basic signals are observed at 70, 59 and 37 ppm. That we can explain is that we can notice
some impurities or unknown signals at 20 ppm. The signals at 13 and 30 ppm are small but
(marked with asterisks) are ascribed to residual C2N. We have three signals for the three carbons
the representing C signals is at 70 ppm and seems to be linked with the surface of perovskite.
The signal representing B is at 37 ppm and the signal representing A is at 59 ppm that’s means
that from the one side the 1,3-propanediol is not grafted, but free.
In conclusion, solid state 13
C NMR confirms the mono-grafting of 1,3-propanediol. We don’t
have pillaring like for number of carbons bigger or equal to 4.
HO B O
A C Ta

13. [12]
0102030405060708090100
*
Chemical shift (ppm)
*
Figure 7. Solid-state 13
C CP/MAS NMR spectra of the chemical shift.
B.2.3.4. SEM observation
SEM observation for the compound shows the morphology of crystallites (see figure 8.) with
stratification typical of lamellar compounds. Crystallites are not homogeneous in size.
Figure 8. SEM images of C3(OH)2-HST (the scale bars correspond to 1μm).

14. [13]
B.4. Conclusions
In conclusion, we have described the successful rapid microwave-assisted interlayer
modification of a protonated form of a layered perovskite, HST, via grafting reactions and we
arrive to the desirable compounds and we prove the way of grafting.
For the begging, it is very important to manage right the reactions, to be careful how to grid the
compound but also and in the amount of water. We have to notice that the good wash of the
powder helps to get better crystallinity and reactivity.
We improve that the reaction between the 1,3-propanediol and C2N-HST by microwave
irradiation is very sensible to the quality of the starting product. Also, we get mono-grafting of
1,3-propanediol improved from NMR and IR spectra. We get the same results as a grafting with
2 carbon atoms us it is represented in the figure 4..We don’t have pillaring, that means the diols
to be linked with the perovskite-like slap and from the both sides, that phenomenon is observed
for diols with number of carbon n=4,7,8,9 and 12.

15. [14]
C. Microwave-assisted exfoliation of an Aurivillius phase
C.1. Introduction
C.1.1. What is exfoliation
Exfoliation of layered compounds is wildly considered as a promising method for preparing
unilamellar sheet units (nanosheets). Layered perovskites are suitable for exfoliation because
of their structural properties: strong covalent bonds in the perovskite-like slabs with weaker
interlayer linkages (van de Waals or electrostatic interactions).
The general idea is to weaken the layer-to-layer interactions by enlarging extremely the
interlayer distance. Upon intercalation of specific molecules into the interlayer space of
perovskite hosts, excess solvent molecules, usually water, enter the interlayer space, which
results in a high degree of swelling. The 3D phase collapse after the layers are completely
solvated and the 2D nanosheets are obtained. [1]
Figure 9. Schematic illustration of the swelling and exfoliation processes. [1]
C.1.2. Nanoarchitectures of colloidal suspension
The obtained 2D nanosheets present an extraordinarily rich structural diversity and electronic
properties. They have wildly potential applications in the field of catalysis and electronics[4]
.
The obtained colloidal sheets of layered perovskites are very suitable as 2D building blocks to
create new materials with controlled structures at the nano-scale, because those colloidal sheets
are negatively charged and they present a high 2D anisotropy of crystallites. As we can notice
in the following figure 10. different nanoarchitectures can be obtained. [1]

16. [15]
Figure 10. Examples of different nanoarchitectures.
Layered materials represent a diverse and largely untapped source of two-dimensional (2D)
systems with exotic electronic properties and high specific surface areas that are important for
sensing, catalysis, and energy storage applications. However, like graphene, layered materials
must be exfoliated to fulfil their full potential. For example, films of exfoliated BI2Te3 should
display enhanced thermoelectric efficiency by suppression of thermal conductivity. Exfoliation
of 2D topological insulators such as Bi2Te3 would reduce residual bulk conductance,
highlighting surface effects. In addition, we can expect changes in electronic properties as the
number of the layers is reduced [7]
.
C.1.3. Nanostructured materials
The nanoscale manipulation is the foundation of nanotechnology. The properties of
nanostructured materials can dramatically change with variations in their dimensionality. With
respect to two-dimensional (2D) materials these are often obtained by cleaving weak out of
plane Van der Waals interactions in a layered host, leading to freestanding layers with strong
in plane chemical bonds. This production of extremely thin sheets from layered precursors is
known as exfoliation.
The exfoliation of graphite demonstrated by Geim and Novolosov was achieved essentially by
rubbing graphite on a surface. Such mechanical exfoliated remains the source of the highest-
quality graphene samples available and has resulted in some major advanced. However, it
suffers from low yield and a production rate that is not technologically scalable in its current
form. One possible solution is the exfoliation of layered compounds in liquid to give large
quantities of dispersed nanosheets. This should allow for methods to obtain sizable quantities
of 2D materials that can be processed by using existing industrial techniques, such a reel-to-
reel manufacturing.

17. [16]
C.1.4. Liquid phase exfoliation - until now
One of the most popular methods is the Ion exchange methods which take advantage of the fact
that LDHs, and some metal oxides contain an exchangeable interlayer of cationic counterions.
Ions can be exchanged for protons by soaking in acidic solutions. The protons can be exchanged
for bulky organic ions, leading to substantial swelling. Alternatively, some clays containing
small monovalent ions such as sodium swell from intercalation of water. In general swelling
facilitates exfoliation through ultrasonication or shear mixing to give negatively charged
nanosheets. A more recent strategy for exfoliation is to expose the layered material to ultrasonic
waves in a solvent. Such waves generate cavitation bubbles that collapse into high-energy gets,
breaking up the layered crystallites and producing exfoliated nanosheets. One of the oldest
methods of exfoliating layered crystals with low reductive potential is oxidation and subsequent
dispersion into suitable solvents. This method is very long, more than a week. [5]
One more
method to do exfoliation as it is written, and it is part of the liquid methods, is the intercalation.
[7]
From some last publications exfoliation achieved by mechanically shake for 7 days or
manually shaken for up to 18 weeks, of the powder using filtered water and some bulky amines
like TMAOH or TBAOH.[6]
C.1.5. Our purpose
Exfoliated materials also have a range of applications in composites as molecularly thin barriers
or as reinforcing or conductive fillers. Here we review exfoliation, especially in the liquid
phase, as a transformative process in material science, yielding new materials, which are
different from their bulk. The insertion (intercalation) of guest species into the weakly held
interlayer region results in an expansion along the stacking direction, together with a
modification of the physics properties of the host structure. The intercalation of appropriate
species sometimes promotes the simultaneous introduction of solvent (typically water with
many different adds). This work will be a first exploration for the synthesis of nanosheets
through the exfoliation process with many solvents, using microwave irradiation and the
characterization of the powder and suspension. Searching a new faster way to do exfoliation.
C.2. Results and discussion
C.2.1. Conditions of experiments and way of testing
Here we will discuss our results, and make the bases for next researches on this subject. The
most difficult for this project, is to decide which type of test will help to characterize the new
compound. For this first exploration is important to be written and understandable under which
conditions we managed the experimental session.
Having as purpose to do the exfoliation a new fast method for the creation of materials with
new properties we should set some constants conditions. First, we decided to have constant the
duration of the microwave irradiation (1h) and the temperature of irradiation 80 o
C, also the
contained liquid phase in a vial30 never be more than 10 ml. Also, the stirring in the microwave
machine is 800 rpm. In our experiments, the pressure is around 1 bar. Also, the same
experiments processed and with classical conditions, that means using only stirring around 350
rpm, room temperature, the bottle with the compound is covered and the reactions take place
for 7 to 14 days. As a solvent, we started with water and we continue with a combination of
water and TBAOH or ethanol and TBACL. All the samples were washed with water and

18. [17]
collected with acetone. We let the powder with the acetone in a glass disk and after the
evaporation of the acetone we collect the flocculated powder.
C.2.2. Characterization
We are doing liquid exfoliation, that’s means that we have two phases to test. The liquid phase
which become after the reaction, a colloidal suspension with unknown characteristics and
properties. For that we will use first an optical observation, using a laser beam (Tyndall effect)
and after AFM observation of the samples drop casted onto Si(100), previously functionalized
or not by a positively charged polymer (PEI). We have also to check the flocculation, we did
it by using XRD, SEM and FT-IR spectra.
C.2.2.1 Tyndall effect
The following figure 11. shows a red laser beam directed through a colloidal suspension of
C2OH-HST with water and TBA (40% water aldrich) (a), C2(OH)-HST and ethanol (b),
C2(OH)-HST and water (c). It is important to be notice that all the new colloidal suspensions
are stable and they don’t change when we let them in room temperature for long time (several
days).
(a) (b) (c)
Figure 11. Tyndall effect in colloidal suspensions.
C.2.2.2 AFM
For this analysis, we did drop casting on silicon 100 of our suspensions. Here we will describe
how we prepared our samples for the AFM. We are using silicon (100), cut it in small parts,
clean it using a solution of ethanol/water (1:1).
We tried many ways to set the suspension on cleaned silicon. Firstly, we tried with only cleaned
silicon pieces to do drop casting, putting one drop of the suspension but the drop doesn’t dry.
After we tried to cover the silicon pieces with a solution of polyethyleneimine (PEI) (5 g PEI

19. [18]
per 1 L of water). For the coating, we let the silicon in this solution for 20 minutes. We let them
to be dried and after we put only one drop of the suspension. Here if the suspension has been
done from solution with water and other solvent, the drop doesn’t dry. Also, we realized that
the solution of PEI was too concentrated for the pictures of the suspension, that means that it
doesn’t help to recognize the colloids from the drops. Last try was to use less concentrated
solution of PEI (2.5 g PEI per 1 L of water). But also here the only dried suspension was the
one with only ethanol as a solvent.
Recognize the pictures of the AFM: for the topography (topo) the dark part is low and the bright
are heights. For the corresponding Phase (Phase) the dark part is compliant and the bright part
is stiff.
C.2.3. Experiments of exfoliation
The following Table 1. gives all the experimental tries to do exfoliation, on many different
phases of a functionalized material, used as first material perovskite. Follows all the
observations and characterized tests results.
Compound Solven Add Method Temperature Stirring Pres Pow Duration Washes experiments
(name & mass) (name and mass) (name & mass) (o
C) (rpm) sure (bar) er (hours or days)
C2OH-HST water - microwave 80 800 - 40 1h MN059
0.02 gr 10.00 ml -
C2OH-HST water -
Classical
Conditions room 350 - - 7 days MN060
0.02 gr 30.00 ml water
2 times
C2OH-HST water
TBA(40% water
aldrich) microwave 80 800 - 40 1h water MN063
0.02 gr 8.80 ml 1.26 ml 2 times
C2OH-HST water
TBA(40% water
aldrich)
Classical
Conditions room 350 - - 7days water MN065
0.02 gr 30.00 ml 1.26 ml 14days 3 times MN068
0.03 gr
C2OH-HST water
TBA(40% water
aldrich) microwave 80 800 - 70 1h water MN067
0.02 gr 8.80 ml 1.26 ml 3 times
C4N-HST water
TBA(40% water
aldrich) microwave 80 800 - 40 1h water MN070
0.02 gr 8.80 ml 1.26 ml 3times
C2N-HST water
TBA(40% water
aldrich) microwave 80 800 - 40 1h water MN072
0.02 gr 8.80 ml 1.26 ml 3 times
C4N-HST water
TBA(40% water
aldrich)
Classical
Conditions room 350 - - 14days water MN069
0.03 gr 30.00 ml 1.26 ml 3 times
C2N-HST water
TBA(40% water
aldrich)
Classical
Conditions room 350 - - 14days water MN071
0.03 gr 8.80 ml 1.28 ml 3 times

20. [19]
C.2.3.1 Observations
MN059
Starting compound is the functionalized C2O-HST and the solvent only water, after the reaction
in the microwave we wait until the powder fall in the bottom of the bottle and we observed the
Tyndall effect after one hour, after 24 hours and after 2 weeks, it exists that’s means that after
the reaction we get a permanent colloidal suspension. We separate the flocculation from the
suspension and we let the powder to be dried.
For the flocculation, we did XRD and IR spectra, both of them show the hydrolysis of the
compound.
For the suspension, we did AFM and we observe nanosheets which are destroyed.
MN060
Starting compound is the functionalized C2O-HST and the solvent only water, after the reaction
by classical conditions we wait until the powder fall in the bottom of the bottle and we observed
the Tyndall effect after one hour, after 24 hours and after 2 weeks, it exists that’s means that
after the reaction we get a permanent colloidal suspension.
For the flocculation, we did XRD and IR spectra, from the XRD diagram we get an interlamellar
(11.58 nm) , which is different from the one we get when we have only HST. Also from the IR
spectra we can recognize that after the reaction we didn’t lost the organic part and also close to
the signal of Ta-O we can notice one more signal which create questions.
For the suspension, we did AFM and we observe nanosheets and slabs. Figure 12. Is the AFM
picture using silicon 100 coated with PEI (5g/L). We can observe nanosheets, but are apparently
HST water
TBA(40%water
aldrich) microwave 80 800 - 40 1h water MN073
0.02 gr 8.80 ml 1.26 ml 3 times
C2OH-HST ethanol - microwave 80 800 - 40 1h water MN075
0.02 gr 10 ml 3 times
C2OH-HST ethanol TBACL microwave 80 800 - 40 1h water MN076
0.02 gr 8 ml 0.1 gr 3 times
C2N-HST ethanol TBACL microwave 80 800 - 40 1h water MN080
0.02 gr 9 ml 0.1 gr 3 times
C4N-HST ethanol TBACL microwave 80 800 - 40 1h water MN081
0.02 gr 9 ml 0.1 gr 3times
HST ethanol TBACL microwave 80 800 - 40 1h water MN082
0.02 gr 9 ml 0.1 gr 3 times

21. [20]
“destroyed” from the edges into sort of fibers. We tried also and with silicon coating by less
concentrated PEI (2.5 gr per liter water). But the AFM pictures are not clear.
TOPO 1.7 x 1.7 m2
Phase 1.7 x 1.7 m2
TOPO 2.1 x 2.1 m2
Phase 2.1 x 2.1 m2
Figure 12. AFM pictures with topography and corresponding Phase.
MN063
Starting compound is the functionalized C2O-HST and the solvent is water and TBA+
, after the
reaction in the microwave we waited until the powder fall in the bottom of the bottle and we
observed the Tyndall effect after one hour, after 24 hours and after 2 weeks, it exists that’s
means that after the reaction we get a permanent colloidal suspension. We separate the
flocculation from the suspension doing washes with water and we let the powder to be dried.
For the flocculation, we did XRD and IR spectra from the first diagram we get an interlamellar
distance (12.50 nm), which is different from the one we get when we have only HST. Also from

22. [21]
the IR spectra we can recognize that after the reaction we didn’t lost the organic part but also,
we have a little bit TBA around the sheets, that’s means that the powder is not very well washed.
MN065
Starting compound is the functionalized C2O-HST and the solvent is water and TBAOH, after
the reaction by classical method, stirring in room temperature we waited until the powder fall
in the bottom and we observed the Tyndall effect after one hour, after 24 hours and after 2
weeks. We separate the flocculation from the suspension doing washes with water and we let
the powder to be dried.
For the flocculation, we did XRD and IR spectra from the first diagram we get an interlamellar
distance (14.8 nm), which is different from the one we get when we have only HST. We can
say that from this XRD diagram we did swelling but we need more tests for the flocculation to
be sure. Also from the IR spectra we can recognize that after the reaction we didn’t lost the
organic part but also, we have a little bit TBA around the sheets, that’s may mean that the
powder is not very well washed.
MN068
Here we can notice, almost the same results for the flocculation like in the previous sample.
The difference is for the crystallinity which looks more bad from the XRD and that may we lost
the signal of C-O as the IR spectra saw us.
MN067
We have the same results as for the sample MN063, that’s mean that the reaction is stable for
these conditions we set up.
MN070
Starting compound is the functionalized C4N-HST and the solvent is water with TBA+
, after
the reaction by microwave irradiation we wait until the powder fall in the bottom of the bottle
and we observed the Tyndall effect after one hour, after 24 hours and after 2 weeks, it exists
that’s means that after the reaction we get a permanent colloidal suspension.
For the flocculation, we did XRD and IR spectra, from the XRD diagram we get an interlamellar
distance (10.99 nm), which is similar with the one we get when we have only HST. Also from
the IR spectra we can recognize that after the reaction we lost the organic part and maybe we
can say that we have delamination.
MN072
Starting compound is the functionalized C2N-HST and the solvent is water with TBA+
, after
the reaction by microwave irradiation we wait until the powder fall in the bottom of the bottle
and we observed the Tyndall effect after one hour, after 24 hours and after 2 weeks, it exists
that’s means that after the reaction we get a permanent colloidal suspension.

23. [22]
For the flocculation, we did XRD and IR spectra, from the XRD diagram we get an interlamellar
distance (10.66 nm), which is similar with the one we get when we have only HST. Also from
the IR spectra we can recognize that after the reaction we didn’t lost the organic but we still
have around the powder TBA+
.
MN069
Starting compound is the functionalized C4N-HST and the solvent is water and TBA+
, after the
reaction by classical method and duration 14 days, stirring in room temperature, we waited until
the powder fall in the bottom and we observed the Tyndall effect after one hour, after 24 hours
and after 2 weeks. We separate the flocculation from the suspension doing washes with water
and we let the powder to be dried.
For the flocculation, we did XRD and IR spectra from the first diagram we get an interlamellar
distance (13.63 nm), which is different from the one we get when we have only HST. We can
say that from this diagram we did swelling but we need more tests for the flocculation to be
sure. Also from the IR spectra we can recognize that after the reaction we didn’t lost the organic
part but also, we have a little bit TBA around the sheets, that’s may mean that the powder is not
very well washed.
MN071
Starting compound is the functionalized C2N-HST and the solvent is water and TBAOH, after
the reaction by classical method and duration 14 days, stirring in room temperature, we waited
until the powder fall in the bottom and we observed the Tyndall effect after one hour, after 24
hours and after 2 weeks. We separate the flocculation from the suspension doing washes with
water and we let the powder to be dried.
For the flocculation, we did XRD and IR spectra from the first diagram we get an interlamellar
distance (13.08 nm), which is different from the one we get when we have only HST (bigger)
also it is appears a new pic ( 16.64 nm) which we can’t explain yet. Also from the IR spectra
we can recognize that after the reaction we didn’t lost the organic part but also, we have a little
bit TBA around the sheets, that’s may mean that the powder is not very well washed.
MN073
Starting compound is the functionalized HST and the solvent is water with TBA+
, after the
reaction by microwave irradiation we wait until the powder fall in the bottom of the bottle and
we observed the Tyndall effect after one hour, after 24 hours and after 2 weeks, it exists that’s
means that after the reaction we get a permanent colloidal suspension.
For the flocculation, we did XRD and IR spectra from the first diagram we get two interlamellar
distance (16.37 nm) different from the HST. We need more tests for that to understand what
happen. Also from IR spectra we are not able to have some results.
MN075

24. [23]
Starting compound is the functionalized C2OH-HST and the solvent is ethanol, after the reaction
by microwave irradiation we wait until the powder fall in the bottom of the bottle and we
observed the Tyndall effect after one hour, after 24 hours and after 2 weeks, it exists that’s
means that after the reaction we get a permanent colloidal suspension.
For the flocculation, we did XRD and IR spectra, from the first diagram we get two new
interlamellar distance (16.57 nm and 12.35 nm), different than the one the reactant had. From
IR spectra, we can observe the organic still there.
For the suspension, we did AFM, from the pictures we can observe sheets which are thin about
2-3 nm. Also, we can notice more than one phases, to be more specific we can observe some
black holes which are maybe another unexpected molecular film.
MN076
Starting compound is the functionalized C2OH-HST and the solvent is ethanol with TBACL,
after the reaction by microwave irradiation we are waiting until the powder fall in the bottom
of the bottle and we observed the Tyndall effect after one hour, after 24 hours and after 2 weeks,
it exists that’s means that after the reaction we get a permanent colloidal suspension.
For the flocculation, we did XRD and IR spectra, from the XRD diagram we can observe a
different structural modification of the powder, we lost the interlamellar distance of the reactant
but we get two different now (15.60 nm and 12.93 nm), we have to test it more to estimate what
exactly happen during the reaction. Also, the IR spectra saw us that we didn’t lost the organic
phase from the powder.
MN080
Starting compound is the functionalized C2N-HST and the solvent is ethanol with TBACL, after
the reaction by microwave irradiation we wait until the powder fall in the bottom of the bottle
and we observed the Tyndall effect after one hour and after 24 hours, it exists that’s means that
after the reaction we get a permanent colloidal suspension.
For the flocculation, we did XRD and IR spectra, from the first diagram we get a different
interlamellar distance (13.48 nm). Also from IR spectra we can observe that we maybe the
powder is not well washed from TBACL.
MN081
Starting compound is the functionalized C4N-HST and the solvent is ethanol with TBACL, after
the reaction by microwave irradiation we wait until the powder fall in the bottom of the bottle
and we observed the Tyndall effect after one hour and after 24 hours, it exists that’s means that
after the reaction we get a permanent colloidal suspension.
For the flocculation, we did XRD and IR spectra, from the first diagram we get a different
interlamellar distance (12.66 nm). Also from IR spectra we can observe that we maybe the
powder is not well washed from TBACL.

25. [24]
MN082
Starting compound is the functionalized HST and the solvent is ethanol with TBACL, after the
reaction by microwave irradiation we wait until the powder fall in the bottom of the bottle and
we observed the Tyndall effect after one hour and after 24 hours, it exists that’s means that after
the reaction we get a permanent colloidal suspension.
For the flocculation, we did XRD and IR spectra, from the first diagram we get a similar
interlamellar distance like the reactant but sort. Also from IR spectra we can observe that the
powder is same as the reactant.
C.2.4 Conclusions
This first insight exploration of exfoliation for functionalized surfaces using microwave
irradiation have been done. These experiments open a new route of research which can product
many new materials with new properties. The part of characterization is not completed. We
realize that for the suspension, drop casting doesn’t work so we propose for the
functionalization of the surface of Si (100), spin coating with another polymer coating. Also for
the flocculation we need more tests like SAX’s to explore how exactly is the morphology of
the powder. Also, we have many conditions it is important to be tested in a variety of
combination for them (temperature duration spinning solvent). We realize that the water can
destroy the nanosheets, that’s why we propose to use combination of solvents and another base
of solvent like ethanol. The first understanding of exfoliation by using microwave irradiation
by using several types of solvent obtained in this study and will help for further studies in this
field.

26. [25]
D. Annex
D.1 Synthesis and characterization technics
➢ Microwave synthesis reactor
Microwave syntheses were performed with a microwave synthesis reactor Monowave300 (for
non-acidic conditions) and with a microwave synthesis reactor MultiwaveGO (acidic
conditions).
➢ Elemental analyses
The elemental analysis for C, H and N were mainly carried out at the Service d’Analyse of the
Institut de Chimie de Strasbourg (CNRS-UdS, UMR 7177).
➢ Powder X-ray diffraction (XRD)
The powder XRD patterns were collected with a Bruker D8 diffractometer (CuKα1=0.1540598
nm) equipped with a Lynx Eye detector discriminating in energy.
➢ Thermo Gravimetric and analysis (TGA)
TGA experiments were performed using a TA instrument SDT Q600 (heating rates of 5oC·min-
1
under air stream, using alumina crucibles)
➢ Infrared spectroscopy
FT-IR spectra were collected in ATR mode on a Spectrum II spectrometer (Perkin-Elmer)
➢ Scanning electron Microscopy (SEM)
The SEM images were obtained with a JEOL 6700F microscope equipped with a field emission
gun, operating at 3 kV in the SEI mode.
➢ Transmission Electron Microscopy (TEM)
The TEM images were obtained with a JEOL 2100F microscope equipped with analytical
configuration of spherical aberrations probe corrector, EDX spectrometer, GIF TRIDIEM
spectrometer, classical holders, specific holders, holography bi-prism device
➢ Atomic force microscopy (AFM)
The AFM images were obtained with a Bruker microscope.
➢ Solid state 13C NMR
NMR spectra in solution were recorded using a Bruker AVANCE 300 (300 MHz) spectrometer.
D.2 Synthesis
D.2.1 Starting materials
Bi2SrTa2O9 (BST): A stoichiometric mixture of Bi2O3, SrCO3 and Ta2O5 for the synthesis of
a tablet of 2 mg was heated at 900 o
C for 4h. It is important before the placement in the oven,
all the three parts of solid to be very well grinded, after a good mixing with 10 drops of rudovial
10% we put the compound for 1h in the oven in the temperature of 100-150o
C. After we prepare
the tablets for the oven in the temperature of 1200o
C for 4h. Same procedure and same attention

27. [26]
for the grinding. The grinding must be intermittent 3 or 4 times. It is also important, the color
of the tablet after the second time of high heating to be whiter than the first time.
Anal. Calcd. For BST: (M = 1011.47 g/ml): Bi, 41.32; Sr, 8.66; Ta, 35.77. Found: Bi, 40.10;
Sr, 8.66; Ta, 34.88.
H2Bi0.1Sr0.85Ta2O7 (HST): To 25 mL of a 37% aqueous HCL solution (HCL/water=0.5), 400
mg of BST were added. The BST must be grinded again, before the mixture. The mixture was
heated in the microwave oven at T= 70o
C during 4 h. In the mean incident power was about 5
W. The autogenous pressure was too low to be measured (typically below 1.5 bars). The acid-
treated product was collected after five centrifugations (14000 rpm, 5 min each) the supernatant
was after each centrifugation by distilled water, to collect the solid we used acetone and we let
the sample to be air-dried.
D.2.2 Intercalation of mono n-alkylamines
C2N-HST & C4N-HST: General procedure: ethylamine (C2N) and n-butylamine (C4N) were
used. 150 mg (0.255 mmol) of HST were dispersed in a solution of 25 mmol of amine in a
mixture of 5 mL of THF and 2 mL of water, must to be noticed the need of water for a better
crystallinity of the compound. The mixture was placed in a 30mL vial and heated by microwave
irradiation at 130 o
C, during 1h30min for the first powder and 2h10min for the second one
(maximum incident power: 70 W). In these conditions, the mean incident power was about 10
W, and autogenous pressure was about 7 bars. The obtained white powder was collected after
four centrifugations (140000 rpm, 5min each) the supernatant was replaced after each
centrifugation by distilled water, to collect the solid we used acetone and we let the sample to
be air-dried.
D.2.3 Grafting of n-alcohols into C2N-HST
0.1 g of C2N-HST (HST intercalated by ethylamine) and a mixture of water (1 mL) and 1,3-
propanediol (C3H8O2, 6mL) were sealed in a vial (volume 30mL) heating in the microwave
oven at 130o
C by following an established procedure (heating: as fast as possible to 130o
C;
holding time 2h; cooling as fast as possible to 50o
C; stirring speed 800 rpm; maximum power
70 W). In these conditions, the mean incident power was about 10 W and the autogenous
pressure was about 0-2 bars, not visible to the sensor. After reactions, the samples were washed
with acetone only for three times by using centrifugation (14000 rpm, 5min) and let them be
air-dried to be collected.
Products Formula Mass losses
(water+
organic)
Found
(calcd)
(%)
Mass losses
(organic)
Found
(calcd)
(%)
C3(OH)2-
HST
(HOC3H6O)0.6H1.4Bi0.1Sr0.85Ta2O5.90.3H2O
3.87
(6.1)
3.33
(5.2)
Table 2. Mass losses.

28. [27]
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