July 23, 2008

1

Demirel Lab 2008

FUNCTIONAL NANOSTRUCTURED POLYMERFUNCTIONAL NANOSTRUCTURED POLYMER--

METAL INTERFACESMETAL INTERFACES

Melik C. Demirel, PhDPearce Assistant Professor of Engineering

Materials Research Institute & Huck Life Institute of Sciences

Pennsylvania State University

2

Demirel Lab 2008

Funding �Young Investigator Award, Department of Defense

�Office of Naval Research

�Penn State University

�Institute for Complex Adaptive Matter (ICAM)

�Johnson and Johnson (USA)

�Kisco International (Japan)

�BD International (USA)

Acknowledgement

ICAM

ICAM

3

Demirel Lab 2008

Polymer / Boeing

Polymers are needed in

energy, sustainability,

clean water, health care,

informatics, defense

and security.

Boeing 787:

This new plane is 50%

by weight and 80% by

volume polymer-based

compositeBoeing 787

4

Demirel Lab 2008

Nanofiber Polymers

J. A. Matthews, et al.

Biomacromolecules 2002, 3, 232 –

238.

ELECTROSPINNINGELECTROSPINNING

M. Steinhart,et al., Adv.

Mater. 2003, 15, 706.

TEMPLATE BASED WETTING

rotate

OBLIQUE ANGLE

POLYMERIZATION

Bottom-up Top-Down

Demirel et al, Langmuir,

2007

5

Demirel Lab 2008

Similar Architectures in Nature

Cicada orni wings

Gecko footpad

Structured Structured

PolymersPolymers

100100--200nm structures with high aspect ratio (micron scale length)200nm structures with high aspect ratio (micron scale length)

Duck FeatherButterfly wings

6

Demirel Lab 2008

OBJECTIVE

We are creating nanostructured polymers with controlled physicochemical properties, such as mechanical properties, structure (morphology) and chemistry for applications in the area of nanostructured surface coatings

7

Demirel Lab 2008

TECHNICAL APPROACH

Our method is a bottom-up process based on oblique angle polymerization developed by our group.

In this process, monomer vapors produced by pyrolysis of chemically functionalized precurcors are directed at an oblique angle towards a surface to initiate structured polymer growth.

Radical

Monomer

Radical

Monomer

8

Demirel Lab 2008

Metallic, ceramic, and organic nanostructured films

Helical Si helical Au helical Alq3 parylene-PPX

Lu, RPI Zhao, U. Georgia Brett, U. Alberta Demirel, Penn State

Short history of oblique angle deposition

Kundt 1876—first columnar film

Hansma 1950—first study of morphology

Messier, Lu, Brett ~1990—metallic / ceramic films

Demirel 2005—polymeric films

9

Demirel Lab 2008

Parylene (PPX) deposition

Gorham

1960

Gorham WF.

J Polym Sci Part A-

1, 4(1966), 3027.

Demirel

2007

Langmuir, 23

(11), 5861 -

5863, 2007

10

Demirel Lab 2008

Polymer composition doesn’t change

Structured Film

Planar Film

Demirel, M.C., et al. Langmuir, 23 (11), 5861 -5863, 2007

Structured Film

FTIR TGA

11

Demirel Lab 2008

10 100 1000 10000

100

PPX-Cl

PPX-COCF3

PPX-Br

Column diameter (nm)

Column height (nm)

2000 3000 4000 500050

100

150

200

250

300

Column diameter (nm)

Column height (nm)

Evolution and GrowthScaling: d ~ hp

PPX-C ----- p= 0.12

PPX-Br ----- p= 0.17

PPX-COCF3 ---- p= 0.20

n

ClCl

n

F3C

O

0

12

Demirel Lab 2008

Growth Model

Roughness is destabilized due to oblique angle

Cetinkaya, M., Malvadkar, N., Demirel, M.C., JOURNAL OF POLYMER

SCIENCE PART B: POLYMER PHYSICS, Vol. 46, pg 640-648, 2008.

Ballistic Monte Carlo Method

13

Demirel Lab 2008

Chemistry: Polyimide and PPV

deposition

4,4'-DIAMINODIPHENYL ETHER

PYROMELLITIC DIANHYDRIDE

Co-polymerization (300 ºC,

0.1 Torr) at oblique angle

Polyimide

poly(phenylene vinylene) (PPV)

Polymerization (60 ºC, 0.1

Torr) at oblique angle

PPV

14

Demirel Lab 2008Demirel, M.C., et al. Langmuir, 23 (11), 5861 -5863, 2007

Morphology Control

0

500

1000

1500

2000

2500

0 100 200 300 400 500 600 700

Series1

Series2D

A

Porosity is measured by

BET/QCM

15

Demirel Lab 2008

DC

BA

Controlling: Topology

Si Substrate PDMS Substrate

After

deposition

Before

deposition

16

Demirel Lab 2008

Functional Polymer-Metal Interfaces OBLIQUE ANGLE POLYMERIZED

FILMS

(developed by Prof. Demirel)

1. Liquid Phase Electroless

Metallization2. Vapor Phase Metallization

Applications: Catalyst, nanoparticleassembly, Biosensors, thermal

barriers, neural interfaces

Parameters

• Surface crystal structure• Surface area• Ligand and colloid binding

Parameters• Confinement• Surface crystallinity

Ions →metal nano-clusters Vapor →metal nano-clusters

Surface enhancement: increasing surface area,

introducing porosity, controlled dispersity

Controlled chemical and physical properties:

different monomer chemistry, different film

morphology.

Industrial scale production: relatively

inexpensive, no clean rooms, no lithography or

masks.

17

Demirel Lab 2008

Liquid Phase: Metal Membranes

Demirel, et al. Advanced Materials, 2007

18

Demirel Lab 2008

c

Reduction to Practice

D

500 nm

250 nm

500 nm

0 nm

C

15 µµµµm

Parylene

(helical nanostructure)

Electroless NiParylene

Ni

1 µµµµm

E

Pore

Pore

Ni

Nanostructured parylene films after Ni metallization: (C) SEM (cross-section); (D) AFM (Ni

film top); (E) SEM (Ni film top). Film regions shown in parts (A) and (B) are not the same

as those shown in parts (C), (D), and (E).

Nanostructured parylene films before metallization: (A) SEM (cross-section); (B) AFM (film top)

B

1000 nm

2000 nm

0 nm

500 nm10 µµµµm

A

Parylene

(helical nanostructure)

19

Demirel Lab 2008

Porous

Nickel

Top surface

(SEM)

EDX spectra

Cross Section

(FIB)

Characterization

Demirel, et al. Advanced Materials, 2007

3030--50nm thin porous membrane metal50nm thin porous membrane metal

Selective, covalent binding of Sn-free

Pd(II) nanoparticles at the adsorbed

ligand sites on the nanostructured PPX

surface.

Treatment of the Pd(II)-catalyzed

surface with an electroless Ni bath,

leading to reduction of Pd(II) to Pd(0)

and catalysis of electroless Ni

deposition templated by the

nanostructured PPX surface.

20

Demirel Lab 2008

Functional Polymer-Metal InterfacesOBLIQUE ANGLE POLYMERIZED

FILMS

(developed by Prof. Demirel)

1. Liquid Phase Electroless

Metallization2. Vapor Phase Metallization

Applications: Catalyst, nanoparticleassembly, Biosensors, thermal

barriers, neural interfaces

Parameters

• Surface crystal structure• Surface area• Ligand and colloid binding

Parameters• Confinement• Surface crystallinity

Ions →metal nano-clusters Vapor →metal nano-clusters

Surface enhancement: increasing surface area,

introducing porosity, controlled dispersity

Controlled chemical and physical properties:

different monomer chemistry, different film

morphology.

Industrial scale production: relatively

inexpensive, no clean rooms, no lithography or

masks.

21

Demirel Lab 2008

Vapor Phase: Metal Membranes

Au, Ag, Co, Cu, etc…

metalized

22

Demirel Lab 2008

Vapor Phase: Metal Membranes

AFM SEM

248.0748.72 cm2Deposit Ag

on top

391.9676.98 cm2Only polymer

film

Multiple of

electrode area

(0.1964cm2)

Surface areaSample

QCM /

BET

Results

23

Demirel Lab 2008

Why do we need these type of

nanostructured polymer surfaces?

24

Demirel Lab 2008

Applications

• Mechanical Properties

• Self cleaning

• Biosensor

• Energy / Catalyst

25

Demirel Lab 2008

Microtribology of Nanostructured

Materials

N

Do material anisotropies

influence friction, deformation

processes?

26

Demirel Lab 2008

Tribology of Nanostructured

Materials

- Films of Molecules or FibersFriction Anisotropy Collective Buckling

Sliding direction

Liley et al., Science 280 (1998) 273-275

Thiolipid monolayer on mica

Cao et al., Science 310 (2005) 1307

27

Demirel Lab 2008

Microtribometry Protocol

•17 ± 4 μm Conospherical

Diamond Tip

•8 μm Wear Track

•40 Sliding Cycles

Increasing Load TestConstant Load Test

Load and displacement profiles

• 100 μN Constant Load

• 300 μN Ramped LoadK. Wahl, E. So, M. Demirel

28

Demirel Lab 2008

Contact Depths During Sliding

300

250

200

150

100

50

0

-4 -3 -2 -1 0 1 2 3 4

Test 118, 100 uN load, 0-degree orientation

Lateral Position (um)Depth (nm)

Against columns

With columns

Sliding Direction

300

250

200

150

100

50

0

-4 -3 -2 -1 0 1 2 3 4

Test 118, 100 uN load, 0-degree orientation

Lateral Position (um)Depth (nm)

Against columnsAgainst columns

With columnsWith columns

Sliding Direction

300

250

200

150

100

50

0

-4 -3 -2 -1 0 1 2 3 4

Test 122, 100 uN load, 180-degree orientation

Lateral Position (um)

Depth (nm) Sliding Direction

Against columns

With columns

300

250

200

150

100

50

0

-4 -3 -2 -1 0 1 2 3 4

Test 122, 100 uN load, 180-degree orientation

Lateral Position (um)

Depth (nm) Sliding Direction

Against columnsAgainst columns

With columnsWith columns

Parallel Sliding

0°

180°

Anisotropy? YES

Tip penetrates

deeper into film

when sliding with

column tilt

Arrows indicate the

sliding direction

K. Wahl, E. So, M. Demirel

29

Demirel Lab 2008

Depth Response w/ Load

800

700

600

500

400

300

200

100

0

-6 -4 -2 0 2 4 6

Pre-scan Post-scan

Increasing Load

Lateral Displacement (um)

Depth (nm)

With Columns

Against Columns

800

700

600

500

400

300

200

100

0-6 -4 -2 0 2 4 6

Increasing Load

Lateral Displacement (um)

Depth (nm)

Pre-scan

Post-scan

Perpendicular to Columns

Depth anisotropy observed for all ordered

films over a wide range of conditions

K. Wahl, E. So, M. Demirel

30

Demirel Lab 2008

Penetration Depth vs. Load

Highly confident statistics demonstrating

depth anisotropy

K. Wahl, E. So, M. Demirel

31

Demirel Lab 2008

Mechanical Deformation Hysteresis

H

?b

∑= xb FEd

H4

3

3

64

πδ

Beam Equation

ω=÷÷

∂∂

∂∂

2

2

2

2

x

uEI

x

Solution

?c

Hooke’s Law

L

LE

A

F ∆=

∑= yc FEd

H2

4

πδ

Solution

+=+= ∑∑ )sin()cos(

3

164)sin()cos(

2

2

2αα

παδαδ

yxcb FFd

H

Ed

HDepth

Sliding perpendicular to film results in no hysteresis, predicted depths between with/against

• Variations in total penetration depth may be more strongly

correlated to film density, modulus

• Model does not include density, inter-column contact or

friction

32

Demirel Lab 2008

Applications

• Mechanical Properties

• Self cleaning

• Biosensor

• Energy / Catalyst

33

Demirel Lab 2008

Wetting Behavior

Young’s Model

Cassie’s Model

Wenzel’s Mode

Transition Model

+ Gecko State ??? (adhesive + hydrophobic) J. Liang, et al., Adv. Mat, 2007

34

Demirel Lab 2008

Adhesive and

Hydrophobic

Non-

Adhesive and

Hydrophobic

Roll off angle

< 5 degrees

Boduroglu et al, Langmuir, 2007

A B

C D

Surface Wetting

35

Demirel Lab 2008

Possible explanation!!!

0

0.5

1

1.5

2

2.5

3

3.5

4

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

r 2̂ r 3̂

Gravity ~ mg ~ Vg ~ r^3

Capillary ~ Surface Area ~ r^2

Force Balance

Note: Water drop is stable up to 40 microliter.

36

Demirel Lab 2008

Applications

• Mechanical Properties

• Self cleaning

• Biosensor

• Energy / Catalyst

37

Demirel Lab 2008

The Biosensor TreeBIOSENSORS

Electrochemical Optical Mechanical

AMporemetirc Potentiometric Impedimetric Vibrational LuminescenceIntegrated

Optics

Surface Aqustic

Wave

(SAW)

Quartz Crystal

Microbalance

(QCM)

IR

Raman

Fluorescence

Chemi-

fluorescence

SPR

Interferometer

T. Cass, C. Toumazou, Biosensors and Biomarkers, Foresight Project Review

38

Demirel Lab 2008

Raman for Biological Detection

ADVANTAGES

• Reagentless method: No reagent but provides chemical structure information (specificity)

• Single Cell Detection: No amplification of DNA (PRC) or Laboratory growth techniques.

• Applications includes identification of characteristic spectra from viruses, bacteria, or protozoa for biomedical, homeland security (CBW agents), aerospace (aerosols) areas.

• Substrate Preparation: High-throughput technique (advantage of vapor deposition), relatively inexpensive

PITFALLS

• Requires creation of database for infectious agents (Raman database)

• Requires bioinformatics tools for analyzing the database (deconvolution and pattern detection)

E.Coli

B.Cere

us

Demirel et al, Adv. Materials, 2008,

in press

39

Demirel Lab 2008

Raman v.s. SERS

Escherichia coli Raman spectrum and the SERS spectrum

Kneipp, Acc. Chem. Res. 2006, 39, 443-450

--Raman, 1920 (Nobel Prize--1930)

--SERS (1977), Van Duyne and Jeanmaire and, independently, Albrecht and Creighton

HOT-SPOTS

SERS phenomena of silver

nanoparticles

40

Demirel Lab 2008

SERS: Viral and Bacterial Detection

Representative SERS spectra of a) Adenovirus,

b)Rhinovirus, c) HIV Zhao, Nano Lett., Vol. 6, No.

11, 2006

Representative SERS spectra of Gram-negative species: a) E.

coli; b) S. Tennessee; c) K. pneumoniae; d) E. aerogenes;, e) P.

mirabilis; f) P. aeruginosa.

T. Pineda, M.S. Thesis, University of Puerto Rico, 2006

Representative SERS spectra of Gram-positive species: a)B.

subtilis; b) B. cereus; c) B. thuringiensis; d) S. epidermidis; and

e) S. aureus.

41

Demirel Lab 2008

SERS: Strain Identification

Rosch et al. , Analytical Chemistry, Vol. 78, No. 7, April 1, 2006

42

Demirel Lab 2008

SERS Substrates

• Several methods have been implemented for microorganism detection using SERS such as gold nanoparticle coated SiO2, electrochemically roughened metal surfaces, and colloidal metal particles.

Lu.J et.al. Nanotechnology 17 (2006) 5792–5797

Shanmukh et. al. Nano Letters 2006,

6, 2630.

He H. et. al. Langmuir 16,

3846-3851 (2000).

Gunnarsson, L. et al. Applied Physics Letters 78, 802-804

(2001).

Dick. L et. al. J. Phys. Chem. B 2002, 106, 853-860

43

Demirel Lab 2008

SERS DetectionThe lack of reproducibility of these techniques and uniform signal

detection make it difficult to get consistent SERS results.

Example: Influence

of gold nanoparticle

size on SERS

spectrum of

B.megaterium.

Culha et al., Journal of

Biomedical Optics 125,

054015

44

Demirel Lab 2008

Metal layer (Ag, Au)

Infectious agent Raman Laser

Single cell

Nano SERS substrate

0

500

1000

1500

2000

600800

10001200

14001600

18002000

5

10

15

20

Counts

Wave number (cm -1)

Data set

Database

Non-lithography based Polymer/Metal

SERS substrate

Demirel et al, Advanced Materials, in press, 2008

45

Demirel Lab 2008

SERS: Metal Layer Thickness

500 1000 1500 2000

0

10000

20000

30000

40000

50000

1592

1491

1157

1076

817624

SERS, t=60nm

SERS, t=90nm

Raman, BulkCount [a.u.]

Raman Shift (cm-1)

Demirel et al, Advanced Materials, in press, 2008

46

Demirel Lab 2008

SERS: Laser Wavelength

Wave number (cm-1)

500 1000 1500 2000 2500 3000

Counts

Neat FBT by 633nm laser

Au substrate by 633nm laser

Ag substrate by 633nm laser

Ag substrate by 514nm laser

47

Demirel Lab 2008

Roughness control over 2 length scale

100 1000

1

10

100

RMS roughness (nm)

film thickness (nm)

E.F. :1x105

SERS Uniformity: %99

E.F.: 2x105

SERS Uniformity: %93

Demirel et al, Advanced Materials, in press, 2008

48

Demirel Lab 2008

SERS: Life time measurement

.

Not

Measured

1138083437Ag

2369Not

measured

4612Au

After two

months

After one

month

Fresh

sample

Enhancement factor for SERS substrate

49

Demirel Lab 2008

500 1000 1500 2000

600

800

1000

1200

1400

1600

652.50164

724.3908

958.02601

1090.50001

1241.86638

1330.54659

1372.10302

1456.17654

1547.12549

1593.40894

1710.14357

E. Coli

Counts

Raman Shift (cm-1)

500 1000 1500 2000

0

2000

4000

6000

8000

1649.88

1611.121594.3

1559.63

1513.97

1477.01

1332.4

1236.22

1096.28

1078.93

1021.69

937.321

720.308

655.602

237.985

B . Cereus

Counts

R am an Sh ift (cm-1)

Fingerprint of Bacterial Samples: Single Cell

Demirel et al, Advanced Materials, in press, 2008

50

Demirel Lab 2008

400 600 800 1000 1200 1400 1600 1800 2000

0.0002

0.0004

0.0006

0.0008

0.0010

0.0012

Norm

alized C

ount

Raman Shift (cm-1)

E.Coli SERS spectra collected from

25 individual cells

Reproducible Data: The peak at the 1372 cm-1 shows a relative deviation of 15%.

51

Demirel Lab 2008

What is next: Detection of Viruses

Human respiratory syncytial virus (RSV)

Patterned SERS Substrate

(PPX-Au)

500 600 700 800 900 1000 1100 1200 1300 1400 1500

Raman shift / cm-1

0

500

1000

1500

Counts

521.464

889.242 954.426

986.1521003.08

1099.48

1208.51

1226.34

1392.07

1517.19

SERS Spectra of RSV

Cryo-negative stain images recorded at a

magnification of x30,000

MacLennan, J. Virol. 2007;81:9519-9524.

52

Demirel Lab 2008

Applications

• Mechanical Properties

• Self cleaning

• Biosensor

• Energy / Catalyst

53

Demirel Lab 2008

Catalysts activity of Polymer/ Metal

surfaces: Cobalt for Hydrogen ReleaseNaBH4 + 2H2O -> 4H2 + NaBO2

pH = 12

Catalyst NaBH4 concentration (wt. %)

NaOH concentration (wt. %)

Hydrogen release rate (mL/min-g)

Reference

A-26 (Ru based) 20 10 4032 {Amendola, 2000 #12}

IRA-400 (Ru based) 12.5 1 ~9600 {Amendola, 2000 #11}

Pt/C 10 5 23,090 {Wu, 2004 #61}

Co-B 2 5 ~3500 {Wu, 2005 #21}

Pt-LiCoO2 5 5 ~24000 {Krishnan, 2005 #58}

Ru-C 10 10 6250 {Dong, 2003 #62}

Co-B 25 3 ~7500 {Lee, 2007 #18}

Co-PPXC 2.5 10 ~1500-7000 This work

54

Demirel Lab 2008

Cobalt Substrate Preparation

A B

0 20 40 60 80 100 120

0

20

40

60

80

100

Co. Wt [%

]

Co. Bath Time [min]

C

0 20 40 60 80 100 120

30

60

90

Surface Roughness [nm]

Cobalt Bath Time [min]

D

Malvadkar N., Park, S., Macdonald, M., Wang, H., Demirel, M.C.,

JOURNAL of POWER SOURCES, in press, 2008.

55

Demirel Lab 2008

Cobalt Catalyst Results

0 50 100 150 200 250

0.0

0.1

0.2

0.3

0.4 Nanostructured PPX-Co

Planar PPX-Co

Hydrogen Release Rate [ml/(m

in*cm

2)]

Cobalth Bath Time [min]

0 5 10 15 20 25

0.0

0.1

0.2

0.3

0.4

0.5

Cobalt 100 min

Hydrogen R

elease Rate [mg/(min*cm

2)]

NaBH4 Concentration [%]

11.5 12.0 12.5 13.0 13.5

0.14

0.16

0.18

0.20

0.22

0.24

0.26

0.28

Cobalt 100 min

Hydrogen R

elease R

ate [ml/(m

in*cm

2)]

pH value

Hydrogen formation from

Sodiumborohydride (Cobalt as

a catalyst)

NaBH4 + 2H2O -> 4H2 + NaBO2pH = 12

Concentration and

pH dependence

Malvadkar N., Park, S., Macdonald, M., Wang, H., Demirel,

M.C., JOURNAL of POWER SOURCES, in press, 2008.

56

Demirel Lab 2008

Conclusions1. Structured polymers are grown, for the first time, by an

oblique angle polymerization method. Structured Polymer growth obeys a scaling law and the growth can be modeled with a ballistic Monte Carlo method.

2. Structured Polymers offer the possibility of fabricating surfaces exhibiting tunable physical properties (i.e. modulus, hydrophobicity, toughness, porosity, etc..) by systematically varying and controlling the chemistry, morphology, and topology at the same time.

3. Structured Polymer technology is a simple and inexpensive method for the functionalization of surfaces for industrial scale applications. Applications for structured polymers: Biomedical coatings, Self Decontaminating Surfaces, Biosensors, Catalyst supports, sensor platform, Enzyme Stability, etc…

57

Demirel Lab 2008

Demirel Lab.

Demirel Lab:

•Post-doctoral Fellows: Dr. Serhan

Boduroglu, Dr. Hui Wang

•Graduate Students: Eric So, Ping Kao,

Niranjan Malvadkar, Murat Cetinkaya, Rama

Gullapalli, Sunyoung Park

•Undergraduates: Ashlee Mangan, Tomas

Marko, Brendon Purcell, Mike Anderson

Outside (Active Collaborators):

•Walter Dressick(NRL): Metallization

•David Allara(Penn State): SERS

•Kathy Wahl (NRL): Mechanical Properties

•Mary Poss (Penn State): Infectious Diseases

http://www.personal.psu.edu/mcd18/

58

Demirel Lab 2008

Thank you

More information and technical documents

are available at our group web site:

http://www.personal.psu.edu/mcd18/