2. Background
BLOCK COPOLYMERS (BCP): class of macromolecules produced by covalently
bonding two or more chemically distinct polymer blocks.
S.B. Darling / Prog. Polym. Sci. 32 (2007) 1152–1204
rochester.edu, empirenews.net,brunton.com
Some applications of BCP
thin films:
• Nanolithography
• High-density information
storage media
• Nanofilters

3. Gradient Surface Energy Substrate
UV LIGHT
Si
SAM (F-OTS)
LVNDF
Si
SAM (F-OTS)
o LVNDF – Linear variable neutral density filter
44.09 mJ m-215.26 mJ m-2
o SAM (F-OTS) – Self assembled monolayer
(fluoride octyltrichlorosilane)
o Si – Silicon Wafer

4. STRUCTURE OF STABLE BCP FILMS
- Polystryrene (PS)
- Polymethylmethacrylate (PMMA)
Annealing
DIA/Thermal
Si
SAM (OTS)
Si
SAM (OTS)

5. Direct Immersion Annealing (DIA)
A. Modi, S. M. Bhaway, B. D. Vogt, J. F. Douglas, A. Al-Enizi, A. Elzatahry, A. Sharma, and A. Karim, ACS Appl. Mater. Interfaces ACS Applied Materials &Amp; Interfaces 7,
21639 (2015).
As Cast
Pre-annealed Film
Objective : Use a gradient surface energy to determine stable to unstable transition point of
BCP thin film

6. Polymer: Poly(styrene-b-methyl methacrylate)
Mn: PS (33000) – PMMA (33000)
Annealing method: DIA – 10 min
45.68 mJ m-2
15.26 mJ m-2

7. DIA – 50 min
DIA – 30 min

8. Polymer: Poly(methyl methcrylate)
Mn: PMMA (24000)
Aneling method: DIA – 10 min
44.09 mJ m-2
17.25 mJ m-2

9. DIA – 50 min
DIA – 30 min

10. 0
5
10
15
20
25
14.00 24.00 34.00 44.00
DewettingArea[%]
Surface Energy [mJ m-2]
PMMA
10 min
30 min
50 min
γc-exp = 22.10 mJ m-2
0
5
10
15
20
25
30
15.00 20.00 25.00 30.00 35.00 40.00 45.00
DewettingArea[%] Surface Energy [mJ m-2]
PS-PMMA
10 min
30 min
50 min
γc-exp = 22.38 mJ m-2
Dewetting Area (%)

11. 0
5
10
15
20
25
15.00 16.00 17.00 18.00 19.00 20.00 21.00
DewettingArea(%)
Surface Energy [mJ m-2]
PMMA
10 min
30 min
50 min
0
5
10
15
20
25
30
15.00 16.00 17.00 18.00 19.00 20.00 21.00
DewettingArea(%)
Surface Energy [mJ m-2]
PS-PMMA
10 min
30 min
50 min
Unstable region : From 15 to 21 mJ m-2

12. 0
5
10
15
20
25
21.00 26.00 31.00 36.00 41.00 46.00
DewettingArea(%)
Surface Energy [mJ m-2]
PMMA
10 min
30 min
50 min
0
5
10
15
20
25
21.00 26.00 31.00 36.00 41.00 46.00
DewettingArea(%)
Surface Energy [mJ m-2]
PS-PMMA
10 min
20 min
30 min
Stable region: From 21 to 46 mJ m-2

13. Surface energies (γ):
• Heptane = 28.4 mJ m-2
• Acetone = 25.2 mJ m-2
• Toluene = 20.14 mJ m-2
γ 𝑆𝑜𝑙𝑣𝑒𝑛𝑡 =
𝑉𝑜𝑙𝑢𝑚𝑒ℎ𝑒𝑝𝑡𝑎𝑛𝑒
𝑇𝑜𝑡𝑎𝑙 𝑉𝑜𝑙𝑢𝑚𝑒
γℎ𝑒𝑝𝑡𝑎𝑛𝑒 +
𝑉𝑜𝑙𝑢𝑚𝑒 𝑎𝑐𝑒𝑡𝑜𝑛𝑒
𝑇𝑜𝑡𝑎𝑙 𝑉𝑜𝑙𝑢𝑚𝑒
γ 𝑎𝑐𝑒𝑡𝑜𝑛𝑒+
𝑉𝑜𝑙𝑢𝑚𝑒 𝑡𝑜𝑙𝑢𝑒𝑛𝑒
𝑇𝑜𝑡𝑎𝑙 𝑉𝑜𝑙𝑢𝑚𝑒
γ𝑡𝑜𝑙𝑢𝑒𝑛𝑒
γ 𝑐 = 𝟐𝟏. 𝟕
𝒎𝑱
𝒎 𝟐
≅ γ 𝒄𝒆𝒙𝒑
Data Analysis
Solvent mixture used: 71.4 % Heptene, 23.8 % Acetone, 4.8 % Toluene

14. Conclusions
• PMMA determined as the wetting block of the BCP
• Direct immersion annealing (DIA) is highly dependent of the surface energy of the
substrate and of the solvent mixture
• Correlation found between solvent mixture surface energy and film stability
- Specifically: determined γc = 22.38 mJ m-2 correlated to theoretical γc from solvent
mixture solvent energy,
Future works
• Perform DIA with different solvent mixtures in order to obtain different γc
• Perform optimization studies on DIA by taking in consideration the
dewetting kinetics together with the ordering kinetics.

15. Acknowledgments