AVS-61 JSJur&RPPad_rpedit

next (nano-extended textiles) research group
…Expanding the Influence of Nanotechnology in Textiles
Influence of Polymer Microstructure and Process
Temperature on the Formation of Tailored ALD Coatings on
Polymers
Richard P. Padbury and Jesse S. Jur
NC State University
Department of Textile Engineering, Chemistry and Science
Raleigh, NC
1

Outline
• Summary of ALD on polymers
• Section 1: Influence of polymer microstructure on ALD
– Objective: Understand how polymer structure affects the
ALD process
• Section 2: Saturation behavior of polymers over broad
temperature range
– Objective: Indentify fundamental growth mechanisms
based on polymer physics
2

Inorganic material toolbox of atomic layer deposition (ALD)
3
Pure Elements
Nitrides
Oxides
[1]Puurunen, R. L., Surface chemistry of atomic layer deposition: A case study for the trimethylaluminum/water process. Journal of Applied Physics 2005, 97 (12).
• ALD – Vapor phase technique for
forming inorganic coatings on
broad range of substrates
• ALD on polymers indicates
dependence on polymer
chemistry
• Infiltration and nucleation within
carbonyl containing polymers
indicates formation of a hybrid
coating
• Research Question:
What are the most advantageous material characteristics and optimal vapor phase
process parameters to exploit a particular functionality in a polymer for a specific
application?

Polymer chemistry and temperature control precursor
nucleation
4
⁻ Polymer
Chemistry
⁻ Temperature
Cross-section TEM of PA-6 infiltrated with trimethylaluminum
Cross-section TEM of trimethylaluminum infiltration in cotton, PP and PA6
Cotton PP PA-6
[2] Sun, Y. et al. Chemical Vapor Deposition (2013)

Experimental Approach
Infiltration Experiments Using In-situ QCM Analysis
A
L
Precursor
dose
Polymer
film
Precursor
Infiltration
QCM data
analysis
Diffusion
of
precursor
molecules
Free Volume
Microstructure
Chemical
reaction
Mass
uptake
(QCM)
5

In-situ QCM Analysis of a Typical ALD Process
6
[1]
[2]
Vacuum
pump
TMA
H2O
N2
Polymer coated
quartz crystal
N2 Purge
Direction of flow
Dose Sequence:
x(TMA)/N2/H2O/N2)
Electrodes
Exposure
surface
Crystal drawer
Heated
reaction
chamber
QCM exposure
surface facing
down
Piezo-electric
quartz crystal
Top
Bottom

QCM analysis of alumina ALD via TMA/H2O indicates
step-wise growth
7
ALD Parameters:
• Number cycles: 50
• Dose Sequence: TMA/N2/H2O/N2
• Dose times (sec): 0.2/30/0.2/45
• Pressure (Torr): 1
• Temperature (oC): 60
[3] RP Padbury, JS Jur. Effect of Polymer Microstructure on the Nucleation Behavior of Alumina via Atomic Layer Deposition. J. Phys. Chem. C. 118 (32), 18805-18813

Polymers possess nucleation period prior to typical ALD
growth
8
ALD Parameters:
• Number cycles: 50
• Dose times (sec): 0.2/30/0.2/45
[3] RP Padbury, JS Jur. Effect of Polymer Microstructure on the Nucleation Behavior of Alumina via Atomic Layer Deposition. J. Phys. Chem. C. 118 (32), 18805-18813
PBT = Poly (butyl terephthalate) PPMA = Poly (propyl methacrylate)

Section 1: Influence of polymer microstructure on ALD
• Expected Outcome:
– Mass uptake behavior dependent on Tg of each polymer
– Steric hindrance due to size of pendant groups
9
• Question: How does polymer microstructure influence the ALD process
• Method: Investigate single TMA dose in a series of polymers with varied
microstructures
[3] RP Padbury, JS Jur. Effect of Polymer Microstructure on the Nucleation Behavior
of Alumina via Atomic Layer Deposition J. Phys. Chem. C. 118 (32), 18805-18813

Larger absorption of TMA in PBT film with lowest Tg
10
Infiltration Parameters:
• Temperature: 60oC
• TMA Dose time (sec): 0.2
• N2 purge time (sec): 1200
Tg~66oC
Tg~80oC
PET
PBT

11
Tg~20oC
Tg~35oC
Tg~65oC
Tg~115oC
Tg~20oC
Tg~35oC
Tg~65oC
Tg~115oC
Larger absorption of TMA in PBMA with lowest Tg
[4] http://pslc.ws/macrog/tg.htm

Absorption of TMA correlated to Tg of polymer film
relative to reactor temperature
12
Tg~115oC
Tg~65oC
Tg~35oC
Tg~20oC
Free Volume
Theory
[6] P. Neogi, Diffusion in Polymers. In New York : Marcel Dekker: 1996.

Free volume distribution influences TMA absorption
13[5]Dorkenoo, K. D.; Pfromm, P. H.; Rezac, M. E.. Journal of Polymer Science Part B-Polymer Physics 1998, 36 (5), 797-803.

Increased desorption time of TMA as absorption
increases
14
Dose Sequence: TMA/N2/H2O/N2
Dose times (sec): 0.2/30/0.2/45
Polymer Tg
(oC)
TMA dose
time (sec)
Absorbed
TMA
(ng/cm2)
Desorbed
TMA
(ng/cm2)
Desorption
Time (sec)
PMMA 115 0.2 60 10 50
PEMA 65 0.2 125 75 75
PPMA 35 0.2 375 275 300
PBMA 15 0.2 640 590 450
PET 80 0.2 400 275 75
PBT 66 0.2 2625 2375 120

Precursor infiltration increases desorption time which
influences ALD nucleation
15
ALD Parameters:
• Dose times (sec): 0.2/30/0.2/45
• Extended purge: 0.2/480/0.2/45

• Question: How does temperature affect the infiltration and nucleation
behavior of organometallic precursors?
• Method: Investigate infiltration behavior of TMA using an ALD cycle sequence
with an eliminated water dose (i.e. multidoses)
• Expected Outcome:
– Mass uptake dependence on temperature and polymer chemistry
– Relationship between mass gains above and below Tg
Section 2: Temperature dependant infiltration in
polymers
16
[7] RP Padbury, JS Jur. Temperature-Dependent Infiltration of Polymers during
Sequential Exposures to Trimethylaluminum. Langmuir 30 (30), 9228-9238

Constant TMA absorption in PMMA despite onset of
saturated mass gain
17
• Number cycles: 10 TMA multidoses
• Dose times (sec): 0.2/60/0/60

Nucleation behavior of TMA in PMMA influenced by
polymer/substrate interface
18
• Interface between PMMA and
gold plated quartz creates
gradient in Tg
[8], [9]
• High concentration of surface
polymer chain ends
[8] Keddie, J. L.; Jones, R. A. L.; Cory, R. A. Interface and surface effects on the glass-transition temperature in thin polymer-films. Faraday Discuss. 1994, 98, 219-230.
[9] Xia, W. J.; Mishra, S.; Keten, S. Substrate vs. free surface: Competing effects on the glass transition of polymer thin films. Polymer. 2013, 54, 5942-5951.

PET does not saturate within 10 TMA multidoses
19
• Dose times (sec): 0.2/60/0/60

PET saturates with larger number of TMA doses
20
• Dose times (sec): 0.2/60/0/60
[10] RP Padbury, JS Jur. Systematic study of trimethyl aluminum infiltration in polyethylene terephthalate and its effect on the mechanical properties of polyethylene terephthalate fibers. J.
Vac. Sci. Technol. A 33 (1), 01A112

ToF-SIMS confirms bulk infiltration of TMA in PET films
21
Cross-section TEM of PET infiltrated with 100
doses of TMA at 100oC
ToF-SIMS depth profile of PET infiltrated with
10 and 50 doses of TMA at 100oC
[10] RP Padbury, JS Jur. Systematic study of trimethyl aluminum infiltration in polyethylene terephthalate and its effect on the mechanical properties of polyethylene terephthalate fibers. J. Vac. Sci.
Technol. A 33 (1), 01A112

Nucleation behavior of TMA in PET
22[7] RP Padbury, JS Jur. Temperature-Dependent Infiltration of Polymers during Sequential Exposures to Trimethylaluminum. Langmuir 30 (30), 9228-9238

Glass transition temperature and polymer free volume
influence TMA mass uptake
23
Free volume
theory
α
β γ
[6] P. Neogi, Diffusion in Polymers. In New York : Marcel Dekker: 1996.

Conclusion
• Series of poly-n-methacrylates and polyesters indicate mass gain
dependence on their respective Tg’s
• Polymers with lowest Tg’s relative to reactor temperature possess greatest
absorption of TMA
• Larger absorption of TMA increases desorption time which influences
nucleation behavior using typical ALD cycle sequence
24
Cotton PP PA-6 PET
Surface inorganic Bulk inorganic Sub-surface hybrid Bulk hybrid
Coating morphologies

Graduate Researchers
Postdoctoral Researchers
Jesse S. Jur
Assistant Professor
N.C. State University
jsjur@ncsu.edu
Undergraduates High Schoolers Mannequins
Funding:

End
26

In Situ Quartz Crystal Microgravimetry (QCM)
Electrodes
Exposure
surface
Crystal drawer
Gas injection
Heated
reaction
chamber
QCM exposure
surface facing
down
Piezo-electric
quartz crystal
Top
Bottom
• Principle of QCM relies on the converse piezoelectric
effect
• A piezoelectric crystal placed in an alternating electric field
will oscillate in a mechanically resonant mode
• Changes in frequency are related to changes in mass
27

Motivation: Hybrid Materials
Hybrid Modification
Layer
Organic Materials Inorganic Materials
Benefits:
• Low cost
• Flexibility
• Easy to form
• High throughput
Benefits:
• Excellent thermal
properties
• High dielectric
constants
• Low permeability
• Photocatalytic behavior
• Chemical resistance100 nm
epoxy
PA-6
Hygiene
FiltrationMedical
Benefits:
•United material properties
from each component
•Mix components at
molecular scale increasing
homogeneity
•Overcome mechanical
mismatch between
components
28

Rapid saturation of TMA in PA-6
29
• Dose times (sec): 0.2/60/0/60

Sub-surface infiltration in PA-6
30

AVS-61 JSJur&RPPad_rpedit

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