Probing soft nanostructured interfaces with x-rays

Probing soft nanostructured interfaces with x-rays Oleg Gang Brookhaven National Laboratory, Upton, NY Antonio Checco (BNL) Masa Fukuto (BNL) Ben Ocko (BNL) Kyle Alvine (Harvard) Peter Pershan (Harvard) Diego Pontoni (Harvard)

Supported by the Department of Energy, Office of Basic Energy Sciences

Seung. Kim (U. Mass) Mattew Misner (U. Mass) Thomas Russell(U. Mass) Ting Xu (U. Mass) Alain Gibaud (Univ. du Maine) Detlef Smilgies (Cornell)

Diblock polymer films: order formation. Liquid on nano-patterned surfaces: microscopic picture. Nanoparticles in nano-thick liquids.

Experimental Tools Z I

α

Reflectivity

GID

kin q qz

R qr qz

Bragg rod

qz

qr kout 2θd

β

I Λ∼ 50−100 Α

GISAXS: Diffraction Pattern

o

qz qz,1 qz,2

X-ray reflectivity >>> e-Density profile of the interface

qr,1

qr,2

qr

X-ray Grazing Incidence Diffraction (GID) >>> In-plane structure of 2D ordered system Grazing Incident Small Angle X-ray Scattering (GISAXS) >>> Structure of thin films (1-1000’s nm)

Self-assembled diblock copolymers at surfaces Block Polymers

Hexagonal Phase Orientation Standing-up phase 0.2 0.18 0.16

qz (Å-1)

0.14 0.12 0.1

0.08 0.06 0.04 0.02 0

-0.1 -0.08 -0.06 -0.04 -0.02

0

0.02 0.04 0.06 0.08 0.1

qy (Å-1)

Lying down phase

qz qy

Ordering formation from the solution Interferometer X-ray CCD In-plane structure film thickness

0.08 0.07

0.07 0.06

Xray beam

0.06 0.05

qz (Å -1)

qz (Å-1)

0.05

0.04

0.04

0.03

0.03

0.02

0.02

0.01

0.01

0

-0.06

-0.04

-0.02

0

0.02

0.04

0

0.06

qy (Å-1)

-0.06

-0.04

-0.02

0

0.02

0.04

D

0.06

qy (Å-1)

0.09 0.08

0.08

0.07

0.07

0.06

qz (Å-1)

qz (Å-1)

0.06

0.05

0.05 0.04

0.04

0.03

0.03

0.02

0.02

0.01 0

0.01

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

0.08

0

qy (Å-1)

-0.06

-0.04

-0.02

0

0.02

0.04

0.06

qy (Å-1)

•Liquid-like ordering is detected at ~15% of solvent

0.1 0.09

0.09

0.08

0.08

0.07

qz (Å -1)

0.07

•Crystal-like ordering is observed ~3-5% of solvent

0.05

z

0.05 0.04 0.03

0.04 0.03

0.02

0.02

0.01 0

0.06

-1

q (Å )

0.06

•Surface X-ray scattering and optical interferometry allow in-situ studying of film formation

0.01

-0.08

-0.06

-0.04

-0.02

0

qy (Å-1)

0.02

0.04

0.06

0.08

0

-0.06

-0.04

-0.02

0

qy (Å-1)

0.02

0.04

0.06

Order/disorder Transitions: solvent or thermal PEP-b-PLA Thickness measured with interferometer Order sets in below a critical conc.

Solvent

t/to~1.50

Thermal

TODT=130oC

Liquids on geometrical nano-patterned surfaces: microscopic view Flat surfaces Complete Wetting

Structured surface-

?

Slits, porous media Capillary condensation D

l∼∆µ−β β=1/3, for dispersion

l ∝| ∆µ ∆ |− βµ

*

=

−2γ ( ρl − ρ g ) D

forces

Depends on microscopic Depends on both. interactions Depends on the shape

M. O. Robbins et al, Phys. Rev. A 43, 4344 (1991) C. Rascon and A. O. Parry, Nature 407, 986 (2000) C. Bauer C, S. Dietrich, Phys. Rev E, 1664 (2000)

Geometry dominated

Filling of surface cavities In-plane diffraction

• How nano-cavities are filled with liquid? X22B Filling

X-ray reflectivity from dry and wet surfaces

Normal to surface Electron-density profile

dry fillin growing g

10 nm

10 8 6

Growing

4 2

Prediction range

0 10

• • •

Filling

-3

10

-2

10

-1

10

0

10

1

Adsorption in Cavity (Arbitarary)

From x-ray reflectivity

electrons/area (e/A2 )

Filling of nano-cavities From in-plane

Filling with liquids, while the top liquid layer remains thin (