Probing the internal structure of magnetic nanocomposites – thermo-sensitive gels and lamellar films – respectively by small angle neutron scattering and neutron reflectivity

(1)

HAL Id: hal-00196454

https://hal.archives-ouvertes.fr/hal-00196454

Submitted on 30 Jun 2019

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Probing the internal structure of magnetic

nanocomposites – thermo-sensitive gels and lamellar films – respectively by small angle neutron scattering

and neutron reflectivity

Siham Douadi-Masrouki, Bruno Frka-Petesic, Delphine El Kharrat, Olivier Sandre, Maud Save, Bernadette Charleux, Valérie Cabuil

To cite this version:

Siham Douadi-Masrouki, Bruno Frka-Petesic, Delphine El Kharrat, Olivier Sandre, Maud Save, et al.. Probing the internal structure of magnetic nanocomposites – thermo-sensitive gels and lamellar films – respectively by small angle neutron scattering and neutron reflectivity. The 5th International Symposium on Bioscience and Nanotechnology, Dec 2007, Kawagoe, Japan. �hal-00196454�

(2)

Probing the internal structure of magnetic nanocomposites – thermo-sensitive gels and lamellar films –

respectively by small angle neutron scattering and neutron reflectivity

Siham Douadi-Masrouki ¹ , Delphine El kharrat ¹ , Olivier Sandre ¹ , Maud Save ² , Bernadette Charleux ² and Valérie Cabuil ¹

1 LI2C UMR7612, ² LCP UMR76120, Centre National de la Recherche Scientifique / Université Pierre et Marie Curie - 4 place Jussieu case 51 75252 Paris Cedex 5 France

II) Evidencing the lamellar structure of copolymer films doped or not with magnetic NPs

Nanoscope III (Digital Instrument),Tapping mode

 Tapping mode AFM enables to image 2 types of defects at the surface of the films - “islands”

and “holes” – typical of the lamellar order.

 The lamellar period should be measured from the height difference L ₂ -L ₁ but the AFM tip is too large to reach the second bilayer.

 The lamellar period is 28 nm for an analogous PS-b-P(nBMA) of Mw=82,000 as measured by X- rays reflectivity. [2]

P(nBMA) ₄₂₅ -b-PS ₄₉₀ Film deposited on silicon

e = 60.3 +/- 2.8 nm

(ellipsometric thickness)

P(nBMA) ₄₀₅ -b-PS ₄₆₀ Film deposited on silicon

e = 78.8 +/- 3.6 nm

Pico SPM LE (Molecular Imaging) Images by E. Lepleux (Scientec, Palaiseau, France)

By Atomic Force Microscopy By Neutron Reflectivity

HOLE depth = 6.1 nm

ISLAND height = 6.7 nm

PS SUBSTRATE

AIR L ₁

L ₂

Bibliography:

 [1] G. Coulon, B. Collin, D. Chatenay, Y. Gallot, “Kinetics of islands and holes on the free surface of thin diblock copolymer films”, J. Phys. II France 3 (1993) 697

 [2] G. Vignaud, A. Gibaud, G. Grübel, S. Joly, D. Ausserré, J-F. Legrand, Y. Gallot, “Ordering of diblock PS- PBMA thin films: An X-ray reflectivity study” Physica B 248 (1998) 250

 [3] B. Toperverg, V. Lauter-Pasyuk, H. Lauter, O. Nokonov, D. Ausséré, Y. Gallot, “Morphology of off-specular neutron scattering pattern from islands on a lamellar film”, Physica B 283 (2000) 60

L* ₁

PS-grated NP’s

SUBSTRATE L* ₂

We study nanocomposites consisting of the same iron oxide γ -Fe ₂ O ₃ nanoparticles embedded in polymer matrices:

I) a gel matrix exhibiting a swelling transition triggered by temperature;

II) a lamellar matrix based on the self- assembly of a symmetrical diblock copolymer.

Rotation

Aspiration sous vide

Solution de copolymère avec ou

sansnanoparticules

Substrat de Silicium

Film de copolymère avec ou sans nanoparticules

Preparation of thin lamellar film samples:

Solutions of P(nBMA)-b-PS in toluene are “spin- coated” on smooth substrates (mica or silicone). After deposition, films are annealed at 150°C under vacuum for at least 48h. Their thickness is measured by ellipsometry.

Magnetic nanoparticles (NPs) as building blocks

Fe

₃

O

₄

+ Fe(NO

₃

)

3

γ _-Fe

₂

_O

₃

(maghemite)

R. Massart IEEE Trans. Magn. 1981

^{50 nm}

1) Synthesis ^TEM

Raw polydisperse sample

Size sorted sample

50 nm

Superparamagnetic behavior

M

_s

= m

_s

Φ

Magnetization normalized by its saturation value follows Langevin’s law

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

0 2000 4000 6000 8000 10000

Champ magnétique appliqué (gauss)

M/Ms

Smaller “S1S” size-sorted particles d=6nm

d

₀

(nm) = 6.6 σ = 0.21 Φ (%) = 1.1

a. χ H

m

_s

=2,6x10

⁵

A/M

Magnetic field (Oe)

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

0 2000 4000 6000 8000 10000

Champ magnétique appliqué (gauss)

M/Ms

Larger “C1C” size-sorted particles d=9nm

d

₀

(nm) = 9.1 σ = 0.35 Φ (%) = 2.7

b. χ H

m

_s

=3,5x10

⁵

A/M

Magnetic field (Oe)

Citric acid

2) Grafting of thin ligand layer

Oleic acid

- - - - - - - -

- - - -

Hydrophilic polymer Hydrophobic polymer

Hydrophilic gels

3) Coating with polymer shell

PBMA PS

Hydrophobic films

4) Composite materials

Polystyrene Double Hydrophilic

Diblock Copolymer

PNIPAM

PE 1 000 - 10 000 g/mol Neutral 10 000 - 60 000 g/mol Molecular weights

Cationic-Neutral copolymer

Poly(trimethylammonium ethylacrylate) - b - Poly(acrylamide)

Rhodia Inc.

Double Hydrophilic Diblock Copolymers

Attractive electrostatic

Interaction between citrate grafted NPs

and DHBCs

DHBC – particles solutions

DYNAMIC LIGHT SCATTERING

J-F. Berret, O. Sandre, D. El kharrat, JACS 2006

60 nm < D _H < 80 nm

PTEA(5k)-b-PAM(30k)

Copolymer + S1S NPs (d=6nm)

STATIC LIGHT SCATTERING

S1S Particles d=6nm 2 copolymers : PTEA(5k)-b-PAM(30k)

PTEA(11k)-b-PAM(30k) +

Xp = 2

Xp = 1 + +

excess excess

At X=Xp:

100% species in polymer – particles

clusters

- Dense clusters of nanoparticles with various sizes and shapes.

- Difference between hydrodynamic size (DLS) and core size (TEM) ascribed to neutral polymer shell protecting the clusters against aggregation.

CLUSTERS MORPHOLOGY

BY TEM S1S “smaller” Particles d=6nm

d

_H

=60 nm

C1C “larger” Particles d=9nm

d

_H

=95 nm

PTEA(5k)-b-PAM(30k) copolymer

STRUCTURAL STUDY BY SMALL ANGLE NEUTRON SCATTERING (SANS)

d _o (63Å)

0,001 0,01 0,1 1 10 100

0,01 0,1 1

q (Å

^-1

) Int ens ité (c m

-1

)

5k11k FF D41

NPs inside clusters are close-packed

0,1 1

5k 11k

0,1 1 10 100

0,001 0,01 0,1 1

q (Å

^-1

)

S (q ) x Φ

loc

/ Φ

0

5k 11k

inter-NPs distances forbidden by polymer repulsion S1S Particles (d=6nm) + PTEA(5k)-b-PAM(30k) and PTEA(11k)-b-PAM(30k) copolymers

>

Å ~

2 70

max

= ≈

d q π

Gyration radius 2Rg=3-4 d

₀

Clusters are well dispersed

I(q) / Φ ( ∆ρ )

²

= V

_p

P(q) S(q) = V

_agg

P

_agg

(q)

Correlation distance:

PAXY spectrometer LLB, CEA-Saclay, 2006

Correlation deep

We use both neutron scattering & reflectivy techniques to probe the local structure at the mesoscopic scale.

I) Thermosensitive PNIPAM gels doped with magnetic NPs

H

₃

C CH

₃

Poly(N–isopropylacrylamide), PNIPAM, LCST=32°C

C — NH — ^CH

O CH

₂

CH

n

Semi-interpenetrated network 90% NIPAM-10%AM

Statistical network 90% NIPAM-10%AM

embedded in a 2% cross-linked PNIPAM gel vs. Temperature

0,01 0,1 1 10 100

0,001 0,01 0,1 1

q (Å^-1) I(q) (cm-1 )

Gel@24°C Gel@32°C Gel@34°C Gel@39°C FF D41 D41/PTEA11

NPs are close-packed

d

_max

~ 4 x do

2 π

d

_max

= q

_max

= 75 Å > d

_o

Clusters are packed by the shrinking of the PNIPAM matrix

d

_o

~ 4d

_o

0,1 1 10 100

0,001 0,01 0,1 1

q (Å

^-1

)

S( q) x Φ

loc

/ Φ

0

Gel@24°C Gel@32°C Gel@34°C Gel@39°C D41/PTEA11

STRUCTURAL STUDY BY SMALL ANGLE NEUTRON SCATTERING (SANS)

S1S Particles (d=6nm) + PTEA(11k)-b-PAM(30k) copolymers Gyration radii

Correlation peaks

Correlation deep

Clusters are well dispersed but the inter-clusters distance

decreases then the gel deswells Correlation peaks

shift to higher q

_max

T=24°C T=39°C

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

26 28 30 32 34 36 38 40 42 44 46

température (°C)

m as se /m as se in iti al e

SIPN 90NIPAM - montée 80NIPAM - montée 90NIPAM - montée

SIPN 90NIPAM - descente 80NIPAM - descente 90NIPAM - descente

W ei ght (T ) / W ei ght (24 °C)

Temperature (°C)

Swelling curves for different gels prepared at C

_X-link

=2 mol% and Φ

⁰

=1 vol.% of NPs

Statistical network 90% NIPAM-10%AM Statistical network 80% NIPAM-10%AM

Semi-interpenetrated network 90% NIPAM-10%AM

Poly(acrylamide), PAM

C — NH

₂

O

CH

₂

CH n

TEM + RuO

₄

coloration

Kiessig fringes

 Atom Transfer Radical Polymerization (ATRP)

 High molecular weight : Mn = 112 000 g/mol

 Low polydispersity: Ip ^≈ 1.4

 Symmetrical Dibloc Copolymer: x=425 ≈ y=490

CH

₂

CH

( ) _y

CH

₂

C CH

₃

C

O O

(CH

₂

)

₃

CH

₃

( CH

₂

C ) _x (

CH

₃

C

O O

(CH

₂

)

₃

CH

₃

( ) _x

θ = 0.93°

Neutron wavelengths : 0.5 – 25 Ǻ

EROS spectrometer LLB, CEA-Saclay, 2007

1-layer

Multi-layers → interferences (over-oscillations)

0 2 4 6 8 10 12 14 16

0 20 40 60 80 100 120

épaisseur (nm)

contraste b

L

1

L

2

L

3

PS

PS PS

P(n-BMA)

substrat

air

Neutron scattering length density (109 cm-2)

Thickness (nm)

e

1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

q (nm^-1) = 4 π/λ sin θ

Réflectivité

P(n-BMA)425 -b-PS490 fit

Neutron Reflectivity signal

e L (nm) e film (nm)

Film γ -Fe

₂

O

₃

@PS

L

₁

L

₂

L

₃

L

₄

L

₅

L

_moy

RN Ellipso.

5 γ -Fe

₂

O

₃

@PS3 31.2 45.3 41.5 - - 39.3 117.9 114.6 13 γ -Fe

₂

O

₃

@PS1 34.0 46.1 49.0 54.5 - 45.9 183.6 184.0 14 γ -Fe

₂

O

₃

@PS1 47.3 45.9 47.0 44.4 45.7 46.1 230.3 248.4

Films doped at constant volume fraction Φ

_NPs

= 0.025 vol% and increasing deposited materials amount

Layer number and thickness (nm) Total thickness g/L C

20 30 40

nm

± 1.6

± 4.9

± 17.4 roughness Macroscopic

view →

Bi-layer thickness ≈ 39 nm for the pure P(nBMA) ₄₂₅ -b-PS ₄₉₀ ] copolymer

 The insertion of increasing amount of magnetic nanoparticles leaves both the total thickness and the average period unchanged.

 The nanoparticles are confined inside internal inter-penetrated layers.

 The total thickness of the film and its roughness are proportional to the deposited materials amount.

Film e L (nm) e film (nm)

L

1

L

2

L

3

L

moy

RN Ellipsométrie

∆ e (nm)

8 32.2 48.0 21.5 37.2 111.7 108.1 1.4

9 32.8 48.0 33.3 38.0 114.0 109.4 3.5

10 32.8 48.7 30.0 37.2 111.5 106.6 0.4

0.05%

Layer number and thickness (nm) Total thickness (nm) Ellipsometry Φ

_NPs

0.10%

0.15%

[P(nBMA)

₄₂₅

-b-PS

₄₉₀

]=20 g/L doped with γ -Fe

₂

O

₃

@PS1 at increasing volume fractions Φ

_NPs

Probing the internal structure of magnetic nanocomposites – thermo-sensitive gels and lamellar films – respectively by small angle neutron scattering and neutron reflectivity

HAL Id: hal-00196454

https://hal.archives-ouvertes.fr/hal-00196454

Probing the internal structure of magnetic

nanocomposites – thermo-sensitive gels and lamellar films – respectively by small angle neutron scattering

and neutron reflectivity

Siham Douadi-Masrouki, Bruno Frka-Petesic, Delphine El Kharrat, Olivier Sandre, Maud Save, Bernadette Charleux, Valérie Cabuil

To cite this version:

Probing the internal structure of magnetic nanocomposites – thermo-sensitive gels and lamellar films –

respectively by small angle neutron scattering and neutron reflectivity

Siham Douadi-Masrouki 1 , Delphine El kharrat 1 , Olivier Sandre 1 , Maud Save 2 , Bernadette Charleux 2 and Valérie Cabuil 1

1 LI2C UMR7612, 2 LCP UMR76120, Centre National de la Recherche Scientifique / Université Pierre et Marie Curie - 4 place Jussieu case 51 75252 Paris Cedex 5 France

II) Evidencing the lamellar structure of copolymer films doped or not with magnetic NPs

Nanoscope III (Digital Instrument),Tapping mode

 Tapping mode AFM enables to image 2 types of defects at the surface of the films - “islands”

and “holes” – typical of the lamellar order.

 The lamellar period should be measured from the height difference L 2 -L 1 but the AFM tip is too large to reach the second bilayer.

 The lamellar period is 28 nm for an analogous PS-b-P(nBMA) of Mw=82,000 as measured by X- rays reflectivity. [2]

P(nBMA) 425 -b-PS 490 Film deposited on silicon

e = 60.3 +/- 2.8 nm

(ellipsometric thickness)

P(nBMA) 405 -b-PS 460 Film deposited on silicon

e = 78.8 +/- 3.6 nm

Pico SPM LE (Molecular Imaging) Images by E. Lepleux (Scientec, Palaiseau, France)

By Atomic Force Microscopy By Neutron Reflectivity

HOLE depth = 6.1 nm

ISLAND height = 6.7 nm

PS SUBSTRATE

AIR L 1

L 2

Bibliography:

 [1] G. Coulon, B. Collin, D. Chatenay, Y. Gallot, “Kinetics of islands and holes on the free surface of thin diblock copolymer films”, J. Phys. II France 3 (1993) 697

 [2] G. Vignaud, A. Gibaud, G. Grübel, S. Joly, D. Ausserré, J-F. Legrand, Y. Gallot, “Ordering of diblock PS- PBMA thin films: An X-ray reflectivity study” Physica B 248 (1998) 250

 [3] B. Toperverg, V. Lauter-Pasyuk, H. Lauter, O. Nokonov, D. Ausséré, Y. Gallot, “Morphology of off-specular neutron scattering pattern from islands on a lamellar film”, Physica B 283 (2000) 60

L* 1

PS-grated NP’s

SUBSTRATE L* 2

We study nanocomposites consisting of the same iron oxide γ -Fe 2 O 3 nanoparticles embedded in polymer matrices:

I) a gel matrix exhibiting a swelling transition triggered by temperature;

II) a lamellar matrix based on the self- assembly of a symmetrical diblock copolymer.

Preparation of thin lamellar film samples:

Solutions of P(nBMA)-b-PS in toluene are “spin- coated” on smooth substrates (mica or silicone). After deposition, films are annealed at 150°C under vacuum for at least 48h. Their thickness is measured by ellipsometry.

Magnetic nanoparticles (NPs) as building blocks

Fe

O

+ Fe(NO

)

γ -Fe

O

(maghemite)

R. Massart IEEE Trans. Magn. 1981

1) Synthesis TEM

Raw polydisperse sample

Size sorted sample

Superparamagnetic behavior

M

= m

Φ

Magnetization normalized by its saturation value follows Langevin’s law

Smaller “S1S” size-sorted particles d=6nm

d

(nm) = 6.6 σ = 0.21 Φ (%) = 1.1

a. χ H

m

=2,6x10

A/M

Larger “C1C” size-sorted particles d=9nm

d

(nm) = 9.1 σ = 0.35 Φ (%) = 2.7

b. χ H

m

=3,5x10

A/M

Citric acid

2) Grafting of thin ligand layer

Oleic acid

- - - - - - - -

- - - -

Hydrophilic polymer Hydrophobic polymer

Hydrophilic gels

Siham Douadi-Masrouki ¹ , Delphine El kharrat ¹ , Olivier Sandre ¹ , Maud Save ² , Bernadette Charleux ² and Valérie Cabuil ¹

1 LI2C UMR7612, ² LCP UMR76120, Centre National de la Recherche Scientifique / Université Pierre et Marie Curie - 4 place Jussieu case 51 75252 Paris Cedex 5 France

 The lamellar period should be measured from the height difference L ₂ -L ₁ but the AFM tip is too large to reach the second bilayer.

P(nBMA) ₄₂₅ -b-PS ₄₉₀ Film deposited on silicon

P(nBMA) ₄₀₅ -b-PS ₄₆₀ Film deposited on silicon

AIR L ₁

L ₂

L* ₁

SUBSTRATE L* ₂

We study nanocomposites consisting of the same iron oxide γ -Fe ₂ O ₃ nanoparticles embedded in polymer matrices:

γ _-Fe

_O

1) Synthesis ^TEM

60 nm < D _H < 80 nm

d _o (63Å)