Jan PerlichTU München, Physik-Department LS E13,

James-Franck-Str. 1,D-85747 Garching

Mine MemesaMax-Planck-Institut für Polymerforschung,

Ackermannweg 10,D-55128 Mainz

Nanostructured Films ofSelfencapsulating Inorganic-Organic

Hybrid Materials

DFG-SPP 1181 NANOMAT

PD Dr. P. Müller-Buschbaum Prof. Dr. J.S. Gutmann

Sebastian Nett

Yajun Cheng

Calcination

Ordered crystallites

Ultra-thin films

Spin coatingAmphiphilic

PS-b-PEO

+Sol-gel chemistry

Titan(IV)oxid sol-gel precursor

Micelles in solution

0,00 0,01 0,02 0,03 0,04 0,05 0,06 0,07 0,08 0,09 0,10

0,00

0,01

0,02

0,03

0,04

0,05

0,06

0,07

0,08

0,09

0,10 0,90

0,91

0,92

0,93

0,94

0,95

0,96

0,97

0,98

0,99

1,00

W.(TTIP)

Ternary phase diagram

Goal: Intelligent, nanostructured materials Use of functional inorganic materials TiO2 (crystalline) photocatalysis

photovoltaicY.-J. Cheng, J. S. Gutmann, JACS, 128, 4658 (2006).

Basic materials (before SPP1181)

Properties of prototype solar cells

PS-b-PEO and PMMA-b-PEO as amphiphilic block-copolymers

P3HT / N3 dye / D50 TiO2

0,0

1,0

2,0

3,0

4,0

5,0

6,0

350 400 450 500 550 600 650 700

Wavelengh [nm]

EQ

E /%

PS-b-PEO (19k/6k)~ 20nm particles

PMMA-b-PEO (24k/18k)

~ 50nm particles

P3HT / N3 dye / D20 TiO2

0,0

3,0

6,0

9,0

12,0

15,0

18,0

350 400 450 500 550 600 650 700

Wavelengh [nm]

EQ

E /%

FTOTiO 2

Sub stra te

PHT

Au o r Ag PHT= regioregular Poly(3-hexylthiophene)Dye = cis-(SCN)2 bis (2,2’ bipyridyl-4,4

-dicarboxylate) ruthenium(II)

Can we improve or replace the blocking layer?

Yes, use different polymer! Si

CH3

CH3

O

O n

PEOm

C

CH3

H3C

CH3

O

PDMS

TiO2 (amorph)

Substrate

PDMS TiO2 (krist.)

Substrate

PDMS

400°C

Inert gas

TiO2 (cryst)

Substrate

SiOC

1200°C

Inert gas

Substrate Substrate

400°C

Inert gas

exposed TiO2 (cryst.)

1200°C

Inert gas

Plasmaetch

Substrate

Goal: Integrated self-encapsulation

Central problem: Quality of barrier layer

1.) Pre-test with „conventional“ nanoparticles

Covering of “conventional” titania nanoparticles with

PDMS

Subsequent etching

2.) Synthesize a suitable PDMS block copolymer

How do we test our integrated approach?

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 150

10

20

30

40

50

60

70

80

Film

th

ickn

ess

(n

m)

Etching time (min)

3 min 45 sec

7 min 30 sec

15 min

Plasma etching of PDMS coverednanoparticles

w/o nanoparticles

w/ nanoparticles

Photoluminescence of titania nanoparticles

350 400 450 500 550 600 6500

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

/nm

inte

nsi

ty/a

.u.

TiO2 nanoparticles+PDMS after calcination

TiO2 nanoparticles+PDMS before calcination

bareTiO2 nanoparticles

Considerable increase in the intensity of the peak after etching.

398nm,470nm- self-trapped excitons

localized on TiO6 octahedra

431nm- surface defects

Characterization of Samples

Methods Extracted Information X-Ray Reflection (XRR) Film thickness

Scanning Electron Microscope (SEM) Morphology (real space)

Atomic Force Microscope (AFM) Topography (real space)

Grazing Incidence Small Angle Morphology

X-Ray Scattering (GISAXS) (reciprocal space)

Synchrotron beamline BW4, DESY HASYLAB

Microfocussed beam size 30 x 60 m2

Wavelength = 0.138 nm

Sample detector distance d 2 m

Incidence angle i 0.7 deg

Further Options: SAXS, GIUSAXS, NR & SANS

UV/Vis Spectroscopy, Photoluminescence (PL)

Scattering under grazing incidenceGISAXS

Non-desctructive structural probe

NO special sample preparation required

Yields excellent sampling statistics

Averages over macroscopic regions to provide information on

nanometer scale

Sensitive to surfaces and selective to materials

investigation of structures in the m- to nm-scale

Extracts information about: object geometry, size

distributions & spatial correlations

GISAXS of nanocomposite films

Detector scans Horizontal cuts c (PEO) Horizontal cuts c (TiO2)

Before calcination

After calcination

Ordered clusterednanoparticles

Further orderingof nanoparticles

Calcination

Substrates w/ ordered nanoscale roughness

Detector scans Horizontal cuts c (TiO2) Horizontal cuts c (TiO2)

ITO w/o film

ITO w/ film

Glass w/film

Glass w/o film

SEM: bare ITO

AFM: bare ITO AFM: ITO w/ filmglassITO

GISAXS of plasma etched samples

Detector scans Horizontal cuts c (PDMS) Horizontal cuts c (TiO2)

I: O2 plasma etch, 15 min

(Si/PDMS(TiO2)

II: O2 plasma etch,

3:45 min (Si/PDMS(TiO2))

III: IV after calcination

IV: as prepared

(Si/PS-b-PEO(TiO2))

IIV III II

Data treatment & simulation

Fixed resolution peak

2. Structure peak

1. Structure peak

1. Vertical & horizontal cuts from measured 3D data

2. Mathematical model 2D fit of horizontal cuts

3. Physical model Input of extracted parameters of mathematical fit

2D fit and 3D simulation of scattering pattern

Results of GISAXS

Successful preparation of desired morphologies of ordered nano-

composite films establishment of preparation

Working PDMS plasma etch process Pre-test accomplished

Calcination induces further ordering

GISAXS investigation of ordered nanocomposite films on substrates

with ordered nanoscale roughness

AFM & SEM results are in good agreement with GISAXS

PDMS synthesis: PDMS-b-PEO

Synthetic approaches in literature

1. Coupling via hydrosilylation (Hüsing, Mascos) good yield for low molecular weights (Mw) for suitably high Mw: Yield ~ 2-5% (due to cleaning)

2. Sequential polymerization in presence of crown ethers (Meier)

CH3

O

On

O-

Si

O

Si

O

Si

OCH3

CH3

CH3H3C

H3C

H3C

Crown ether

PDMS did NOT grow in desired extent

in THF

Own approach: Coupling of anionic polymerization and ATRP

Cl Si

CH3O

O

CH3

CH3

CH3

Br

1. Anionic polymerization of PDMS stopped by

2. Polymerization of PBMA carried out by ATRP

THF, RT, CuBr and ligand N

H3C

H3C

N

CH3

N

CH3

CH3

Si

CH3O

O

CH3

CH3

CH3

CH2

C

CH3

H3C

CH3

Si

CH3

CH3

O Si

CH3

CH3

O

n

C

CH3

C O

O

CH2

m

We have block with presence of homopolymers.

HPLC graphs of PDMS-b-PBMA

UV measurement

Light scattering measurement

Better attachment of ATRP initiator

L. Bes, K. Huan, E. Khoshdel, M.J. Lowe, C. F. McConville, D.M. Haddleton, Eur. Poly. J. 39, 5-13 (2003)

ABA triblock copolymers synthesized with different molecular weights

Next step: Attachment of ATRP initiator by esterification of a carbinol

group at the end of PDMS with 2-bromo-iso-butyryl bromide

Then PMMA polymerization by ATRP

PDMS-CNO and PEO-OH

Si

Cl

N

C

O

Si

N C O

C

CH3

H3C

CH3

Si

CH3

CH3

O Si

CH3

CH3

O

n

C

CH3

H3C

CH3

Si

CH3

CH3

O Si

CH3

CH3

O-Li+

n

O

K

O

THF

O

O

OH

n

O

O

OH

nSi

N C O

C

CH3

H3C

CH3

Si

CH3

CH3

O Si

CH3

CH3

O

n

THF, 35°C

Catalyst: dibutyltin dilaurate

THF, reflux

Sn2+

O O-

O-O

dibutyltin dilaurate

No block!

K. Kim, K. E. Plass, A. J. Matzger JACS, 127, 4879 (2005)

1.

2.

3.

Results of synthesis

Desired block hard to be synthesized with shown approaches

Coupling with reactive end remains problematic

Preferred route:

Coupling of anionic with ATRP

Different topologies (bottle brush)

Outlook

Characterization

Setting up process cell GISAXS in-situ investigation of templated hybrid films

Reinforced simulation

Synthesis

PDMS-b-PEO by coupling of end groups (catalyst)

PDMS-b-PHEMA by attachment of ATRP initiator

Material

PDMS barrier layer properties (characterization)

Optimized etch conditions & applied substrate materials

Network

GISAXS for other projects sharing resources

Developing new ideas