Third Day Poster Session, 17 June 2010 - NanoTR-VI

P on
P via
P
P were
P up
Poster Session, Thursday, June 17
Theme F686 - N1123
Superhydrophobic Micropatterned Polymer Surfaces Synthesized by Using Styrene-
Flurometacrylate Random Copolymers
1
1
UUur CengizUP P*, H. Yldrm ErbilP
1
PGebze Institute of Technology, Chemical Engineering Department, 41400, Gebze-Kocaeli
Abstract- In this work, we present a novel method for fabricating polymer thin films containing micro-patterned spherical particles varying in
the range of 400 nm to 8 m by dip-coating process in polymer solution. We can control the distribution of the particle size via adjusting the
concentration of the PS-ran-FMA copolymer, the solvent/non-solvent ratio and withdrawal speed of dip coater. Styrene-fluoromethacrylate
o
random copolymer were synthesized in supercritical carbondioxide (scCOR2R) at 250 bar and 80 P PC using AIBN as a free radical initiator. It was
found that the optimal concentration of polymer solution was 25 mg/mL and withdrawal speed of 41 cm/min to obtain the narrowest particle
distribution on the surface. Surfaces containing the microparticles were characterized with the water contact angle measurement, optical
o
microscopy and SEM. Superhydrophobic surfaces having a water contact angle up to 160P obtained with this novel method.
Polymer surfaces composed of two or three dimensional
repeating uniform units are called “patterned polymeric
1
surfaces”P P. These patterned surfaces are referred to micropatterned
and nano-patterned surfaces with respect to their
dimensions. The polymeric micro/nano patterns provide
some new properties to the surface which change with
respect to chemical nature and shape of the material. For
instance, Erbil et al. (2003) obtained micro-structured gellike
porous super-hydrophobic surfaces having a water
o
contact angle of 160P the method of phase separation
using isotatic propylene (iPP) having a water contact angle
o
of 105P nonpatterned surfaces with different
2
solvent/insolvent couplesP P. There are other methods to
form micro patterned polymeric surfaces. Recently Wang
et al. have obtained micro and nano patterned polymeric
structures via phase separation by dropping polymer
1,4
solution onto non-solventP
P. This method is easier than
soft lithography method whose application is difficult and
expensive.
In this study, uniform micro patterned polymeric
surfaces were obtained with particle diameters changing
between 400 nm and 8 μm. In the first step, p(ST-ran-
FMA) copolymers were synthesized in sc-COR2R medium.
Styrene and Perfluoromethacrylate (Zonly-TM, Dupont)
monomers between 5-20 % in molar concentration were
o
copolymerized in scCOR2 Renvironment at 250 bar and 80P PC.
Polymerization in COR2 Rhas advantages such as being nontoxic,
cheap and no requirement of extra purification
process for the produced copolymers.
In the second step, thin copolymer film coatings were
produced via dip coating glass slides into polymer
solutions obtained by dissolving the copolymers in THF-
MEK mixture (%50 wt) at room temperature and adding
methanol as a non-solvent with varying amount. Then the
optical and SEM images of the formed surfaces were
recorded and the contact angles of the surface were
measured by using the KSV-CAM 200 goniometry.
When the methanol volume fraction was low, scattered
form of particles with no specific geometry were observed
which do not have any specific roughness. With the increase
in the methanol amount, these particles were converted to
repeating, and somewhat uniform spherical particles. The
increase in the dipping rate, the particles shrink uniformly at
the beginning, but after a certain value of dipping rate, then
the agglomeration of particles occurred. Figure 1 shows a
SEM image of the surface obtained at an optimum dipping
speed and different methanol fraction. It is clearly seen from
the results particle sizes decrease with the increase of
methanol fraction. Spherical particles having different
diameters between 2-4 m and 400-800 nm are shown in
fig.1a and 1b respectively
Figure 1. SEM images of 25 mg/mL p(ST-ran-FMA) solution in
THF-MEK solvent mixture (50 wt %) with a) 21,4 b) 33.3 wt %
o
methanol at 22 P PC mixture temparature
In summary, particles shape and dimensions and water
contact angle results were varied as a function of nonsolvent
and copolymer concentration. The increase in the
non-solvent fraction resulted in decrease of the particle
diameter from 8 μm down to 400 nm, and increase in the
o
o
water contact angle from 117P to 160P P.
* Corresponding author: HTucengiz@gyte.edu.trT
[1]Wang Y., Liu Z., Han B., Sun Z., Zhang J., Sun D. Adv.
Funct. Mater. 2005, 15, 655.
[2]Erbil H.Y., Demirel A.L., Avci Y., Mert O. Science 2003,
299, 1377.
[3]Xia Y.N., Whitesides G.M., Angew. Chem. Int. Ed. 1998, 37,
550.
[4] Wang Y., Liu Z.,Huang Y., Han B.,Yang G. Langmuir, 2006,
22, 1928
6th Nanoscience and Nanotechnology Conference, zmir, 2010 647