Epitaxial Single Crystal Surface Patterning and Study of Physical and Chemical
Environmental Effects on Crystal Growth
S. Agbolaghia,b, F. Abbasia,b, S. Abbaspoora,b
a
b
Institute of Polymeric Materials, Sahand University of Technology, Tabriz, Iran
Faculty of Polymer Engineering, Sahand University of Technology, Tabriz, Iran
Experimental
The bromo-capped PEG macroinitiator (PEG-Br) was synthesized and purified according to the
literature [1,2]. The diblock copolymers of PEG-b-PS and PEG-b-PMMA including various
molecular weights of PS and PMMA blocks were synthesized via solution polymerization in
chlorobenzene
(CB,
Merck,
(St)]0/[MI]0/[CuBr]0/[bipy]0
>
99%)
/[CB]0)
=
and
with
240/1/1/3/66)
the
agent
and
ratio
of
([methyl
([styrene
methacrylate
(MMA)]0/[MI]0/[CuCl]0[CuCl2]0/[bipy]0/[CB]0) = 177/1/1/0.07/3/ 375) by atom transfer radical
polymerization (ATRP). The reaction temperatures for St and MMA polymerization were 110
and 65 C, respectively. Due to higher reactivity of MMA in comparison with St [3,4], CuCl2
(Merck, > 98%) was used as deactivator for better controlling of polymerization [5].
Single crystal growth
Solution crystallization was carried out with a dilute concentration of 0.009 wt% in amyl acetate.
The sample was put into the cell tube having desired amount of solvent, and heated to above the
dissolution temperature (Td = 65C) in a temperature-controllable oil bath for 10 min. Then the
cell tube was transferred to a 0C bath lasting 5-7 h for fast crystallization and, subsequently,
immersed into given self-seeding oil bath, and kept for 20 min. The cell tube was then quickly
transferred into a desired isothermal oil bath adjusted at crystallization temperature, and
maintained for 2 days.
Apparatus
The chemical structure of block copolymers was confirmed by 1H NMR spectroscopy on a
Bruker (Avance DPX) spectrometer working at 400 MHz, which was also used to determine the
composition of the copolymers. Deuterated chloroform (CDCl3) was applied as a solvent. The
polydispersity indexes were determined by GPC on a Water1515 gel permeation
chromatography instrument with a set of HT3, HT4, and HT5, μ-styragel columns with DMF
and THF as eluents (1.0 mL/min) for PS and PMMA, respectively,
at 35C. A set of
monodisperse polystyrene standards were utilized for calibration.
To measure the totalthickness of single crystal and identify the surface morphologies by surface
stiffness changes and height variances, the single crystal dispersion was dropped onto a silicon
wafer and quickly dried by a stream of high purity nitrogen and observed under an atomic force
microscope (AFM, Nanoscope IIIA). A silicon tip in the tapping mode was utilized. During
AFM scanning, the cantilever tip-to-sample force required to be carefully adjusted to avoid
damages. For the tip-to-sample force, a large force could lead to tip penetrations into the thin
tethered chain layers, and disturb the materials at the layer surfaces. A scan rate of 1 Hz and a
resolution of 512×512 were selected to take high quality images.
Single crystal structure and morphology was observed in a transmission electron microscope
(TEM, EM 208 Philips) with an accelerating voltage of 100 KeV. The selected area electron
diffraction (SAED) experiments were also conducted to determine the chain orientation in the
copolymer single crystals.
Tables
Table S1. The effect of PS block molecular weight on various parameters of mixed-brush single crystal
11.4
4.0
3.7
0.58
0.30
350
18.2
5.5
6.4
11.5
4.0
3.7
0.41
0.30
342
20.1
4.4
7.8
11.4
4.0
3.7
0.33
0.30
337
(nm)
4.2
Domain size
7.7
PMMA (nm-2)
dtotaldispersed(nm)
16.1
PS (nm-2)
dPSmatrix(nm)
dPMMAdispersed(nm)
dPEGmatrix(nm)
PEG5000-b-PS4600
dtotalmatrix(nm)
Sample
dPEGdispersed(nm)
channels
/PEG5000-b-PMMA8700
PEG5000-b-PS10000
/PEG5000-b-PMMA8700
PEG5000-b-PS14800
/PEG5000-b-PMMA8700
Table S2. The effect of PMMA block molecular weight on various parameters of mixed-brush single
Domain size(nm)
PMMA(nm-2)
PS(nm-2)
dPMMAdispersed(nm)
dPEGdispersed(nm)
dtotaldispersed(nm)
dPSmatrix(nm)
dPEGmatrix(nm)
Sample
dtotalmatrix(nm)
crystal channels
PEG5000-b-PS10000
18.2
5.5
6.4
11.5
4.0
3.7
0.41
0.30
342
18.2
5.5
6.4
12.5
3.4
4.5
0.41
0.25
317
20.1
4.4
7.8
11.4
4.0
3.7
0.33
0.30
337
20.1
4.4
7.8
13.4
2.9
5.2
0.33
0.22
288
/PEG5000-b-PMMA8700
PEG5000-b-PS10000
/PEG5000-b-PMMA13100
PEG5000-b-PS14800
/PEG5000-b-PMMA8700
PEG5000-b-PS14800
/PEG5000-b-PMMA17100
References
1. Jankova, K.; Chen, X. Y.; Kops, J.; Batsberg, W. Macromolecules 1998, 31, 538.
2. Xiao, Q.; Zhang, X.; Yi, J.; Wangand, X.; Zhang, H. Iranian Polymer Journal 2008, 17, 781.
3. Matyjaszewski, K.; Davis, T. P. Handbook of Radical Polymerization, Australia, By John
Wiley and Sons, Inc., Hoboken, 2002.
4. Reining, B.; Keul, H.; Hocker, H. Polymer 1999, 40, 3555.
5. Siegwart, D. J.; Wu, W.; Mandalaywala, M.; Tamir, M.; Sarbu, T.; Silverstein, M. S.;
Kowalewski, T.; Hollinger, J. O.; Matyjaszewski, K. Polymer 2007, 48, 7279.