PS-PLLA - Www2.che.nthu.edu.tw

Block Copolymer Thin Films

Thin Film Morphologies of BCPs
Thickness
Air surface
Substrate
Size
Shape
Order
Orientation
@

Thickness Effect
while t is small for a lamellar phase!
FL: symmetric
surface-parallel full
lamella;
AFL: anti-symmetric
surface-parallel
lamella;
AHY: anti-symmetric
hybrid structure;
HL: half-lamella;
HY: symmetric hybrid
structure;
PL: surfaceperpendicular
lamellae.

At equilibrium, symmetric film systems exhibit a series of
stable films when t = nL 0 (n = 1, 2, 3, 4), whereas antisymmetric
films exhibit a similar series of stable films when t =
(n + 1/2)L 0. It is highly possible to form the island-like
textures for t being not equal to nL 0 and (n + 1/2)L 0.
For symmetric surface energy, first, the domain orientation
was film thickness dependent. In particular, PL gained stability
when t = nL 0, and especially for t < L 0. Second, for neutral
surface energetics, PL was stable for all film thicknesses.
@

Phase diagram of thin film morphologies calculated
with the following parameters: N=200, S 1 B = -0.3 kT,
interaction parameter = 0.1, S 1 B /S2 B = R

For a
cylinder
phase

Surface Tension @

Substrate
Effect

Grain boundary problem
for thicker samples
PS-PB AFM Morphology
Defect free microdomain!
van Dijk, M. A.; van den Berg, R. Macromolecules 1995, 28, 6773.

Large-scale Orientation of Microdomains
Electric field-Induced Orientation
Russell, U of Massachusetts
Surface-Induced Orientation
Russell, U of Massachusetts
Shear-Induced Orientation
Register, Princeton U
■ Patterned Substrate-induced Orientation
Nealey, U of Wisconsin
■ Graphoepitaxy-induced Orientation
Ross, MIT
■ Photo-induced Orientation
Iyoda, TIT

Electric field-Induced Orientation
ε PS = 2.45
ε PMMA = 6
Russell, U of Massachusetts
Russell, T. P. et al. Science, 1996, 273, 931.

Surface-Induced Orientation
Neutral Surface
Russell, T. P. et al. Science 1997, 275, 1458.; Russell, T. P. et al. Nature 1998, 395, 757.
@

Shear-induced Orientation
PS-PEP Cylindrical Morphology
PS
@
Register R. A. et al. Adv. Mater. 2004, 16, 1736.

Patterned Substrate for DSA
(1) Nealey, P. F. et al. Nature, 2003, 424, 411.

Grephoepitaxy-induced Orientation
Confinement effect
Sibener. S. J. et al. Nano Lett. 2002, 4, 273.
@

Photo-induced Orientation
Chromophore molecule
Iyoda, T. et al. J. Am Chem. Soc. 2006, 128, 11010.
@

Evaporation-induced Orientation
Spin Coating-induced Orientation
for PS-PEO
Russell, T.P. et al. Adv Mater 2002,
14, 1373.
Tapping-mode
SPM phase images
of the surfaces of
a) solution cast; b)
spin coated
PS365-PLLA109
(f PLLA v =0.24) thin
films on glass
slides.
a)
Solution casting
spinning
Degradable BCP for mesoporous materials!
Spin-coating for oriented microdomains!
b)
Spin coating

Tapping-mode SPM height images for spin-coated PS365-PLLA109 (f PLLA v =0.24)
thin films on glass slides a) before hydrolysis; b) after hydrolysis.
a) b)
before hydrolysis after hydrolysis
Well-oriented, perpendicular HC nanochannel arrays!

FESEM micrographs of hydrolyzed PS-PLLA samples by viewing
parallel to the cylindrical axes
Top-view
Fracture of substrate
Cross-section view
Spin-coated PS365-PLLA109 (f PLLA v =0.26) thin films on
glass slides after hydrolysis. (50nm thickness)

Thin-film Thickness Control
The plot of film thickness versus spin rate for spin-coated PS365-
PLLA109 (f v
PLLA =0.24) thin films on glass slides. Open circle
indicates the sample thickness measured by SPM whereas open
triangle indicates the thickness measured by depth profile.
Thickness [nm]
180
160
140
120
100
80
60
40
20
Surface Prfiler
0 1000 2000 3000 4000 5000 6000 7000 8000
Spin Rate [rpm]
SPM

Tunable dimensions of nanostructures
Varieties of synthesized PS-PLLA block copolymers having HC microstructures.
Entry
PS83-PLLA41
PS198-PLLA71
PS280-PLLA122
PS365-PLLA109
Mn, PS
[g/mol]
[a]
8900
20700
29400
38200
Mn, PLLA
[g/mol]
[b]
5900
10200
17500
15700
PDI
1.15
1.17
1.21
1.21
0.66
0.73
0.69
0.76
[c]
12.7
25.8
31.4
34.1
d-spacing [nm]
[d]
16.8
28.4
37.2
39.7
[e]
20.8
32.9
35.5
44.2
[c]
7.2
10.7
13.3
17.0
Diameter [nm]
[a] measured from GPC analysis. [b] obtained from integration of 1 H NMR measurement. [c] obtained from
calculation of TEM micrographs. [d] determined from first scattering peak of SAXS. [e] obtained from surface
analysis of SPM.
f PS v
[d]
12.0
19.8
25.6
26.4
[e]
9.1
19.7
23.0
20.9

Topographic PS Nanopattern
Schematic illustration of PS-PLLA and PS-PLA nanopattern
prepared by spin coating.
Continuity and Uniformity of Thin Films
Silicon wafer; Silicon oxide; glass; carbon; ITO glass;
Light emitted diode; Aluminum ----
Coated on various substrates

Spin-coated PS-PLLA thin films
Perpendicular morphology
SPM phase image TEM image
100 nm
40

Proposed Mechanism
Solvent evaporation
d
funnel effect
Step 1: well-ordered microphase separation
Step 2: solvent permeate through specific microdomain
fs
41

Definition of Solvent
Solvent Molar volume χ PS-solvent PLLA-solvent δ solvent
(MPa) 0.5
Vapor Pressure
(mmHg)
Chlorobenzene 102.1 0.36 0.62 19.6 12
benzene 89.4 0.34 0.81 18.6 70
THF 81.7 0.35 0.6 19.4 176
1,1,2-trichloroethane 100.4 0.36 < 0.5 19.6 17.1
1,2-dichloroethane 79.2 0.42 0.44 20.4 61
chloroform 80.7 0.34 < 0.5 19 159.6
χ = χ H + χ S = V i (δ i –δ j ) 2 /RT + 0.34
χ PS-solvent < 0.5 and χ PLLA-solvent >0.5 PS selective solvent
χ PS-solvent < 0.5 and χ PLLA-solvent

PS-PLLA with Cylinder Morphology
Table 1. Varieties of synthesized PS-PLLA block copolymers having HC microstructures.
Entry
Mn, PS
[g/mol]
[a]
Mn, PLLA
[g/mol]
[b]
PDI f PS v
d-spacing [nm] Diameter[nm]
[c] [d] [e] [c] [d] [e]
PS83-PLLA41 8900 5900 1.15 0.65 12.7 16.8 20.8 7.2 12.2 10.1
PS198-PLLA71 20700 10200 1.17 0.71 25.8 28.4 32.9 13.8 18.9 19.7
PS280-PLLA97 29400 14000 1.21 0.72 31.4 37.2 35.5 16.7 23.5 20.0
Control
Molecular weight
Control
Size
PS365-PLLA109 38200 15700 1.21 0.75 34.1 39.7 44.2 17.0 24.6
.
20.9
[a] measured from GPC analysis.
[c] obtained from calculation of TEM micrographs. [e] obtained from surface analysis of SPM.
[b] obtained from integration of 1H NMR measurement. [d] determined from first scattering peak of SAXS.
43

Evaporation Rate Effect
Selective solvent
131.5 mmHg 70 mmHg 12 mmHg
Solvent Evaporation
Vapor Pressure
Evaporation Rate
Time scale of microphase separation
44

Selectivity Effect
Neutral solvent
160 mmHg 61mmHg 17.1 mmHg
Solvent Evaporation
Neutral solvent
Segregation strength ~ χN
45

Solution Casting
Neutral solvent
Crystalline PS-PLLA Amorphous PS-PLA
46

Solution Casting
Selective solvent
Crystalline PS-PLLA Amorphous PS-PLA
47

Molecular Weight Effect
Selective Solvent with Low Evaporation Rate
S83L41
S198L71
S280L97 S365L109
Solvent evaporation
Molecular weight
Segregation strength ~ χN
48

Bottom Morphology
Before hydrolysis
PS PLLA
Hydrophilic substrate
After hydrolysis
Interfacial energy of PS-hydrophilic substrate > Interfacial energy of PLLA-hydrophilic substrate
49

Tg Effect
Side view image of FESEM
100 nm
Phase image
Spin-coated PS-PLLA thin films at the temperature above T gPLLA
but below T gPLLA (ca. 50 o C)
50

PS PLLA
Hydrophilic substrate
Spin coating at room temperature
D PS (glass state) = D PLLA (glass state)
S PS-PS selective solvnet > S PLLA-PS-selective solvent
Permeation
Diffusivity & Solubility
Kinetic control & Dynamic control
PS PLLA
Hydrophilic substrate
Spin coating at 50 O C
D PS (glass state) S PLLA-PS-selective solvent
Permeation (P=DXS)
Diffusivity (D) ~ T g
Solubility (S)
51

Substrate Effect
Glass slide Carbon film
ITO Silicon wafer
52

Thickness Effect
160 nm 80 nm 50 nm
53

Proposed Mechanism
Segregation strength and time scale Permeation (P=DXS)
Selectivity (selective and neutral solvent) Diffusivity (Tg effect)
Evaporation rate Solubility
Molecular weight
Solvent evaporation
Step 1: well-ordered microphase separation
Step 2: solvent permeate through specific microdomain
d
fs
@

Solvent-induced Orientation
SPM phase images
Spin-coated thin film Solvent-annealed thin film
PS-PEO with cylindrical microdomain
Russell, T. P. et al. Adv. Mater. 2004, 16, 226.
39

Nanopatterning for Lamellar Nanostructures
Composition profile
Chemical nanopattern
Height profile
Topographic nanopattern

What is Epitaxy-induced Orientation?

Crystallizable solvent
T max =150 o C
80 o C
T m, BA ≒ 123 o C
Cooling
Benzoic acid (BA)
PLM image
b BA

Large-Scale Orientation for PS-PLLA Lamellae
Spin-coated lamellar thin film
O
C
Induced by
Crystallizable solvent
O [ CH2 C H ] n
O
Oriented lamellar thin film
H C
3
H C
3
CH 3
CH 3
Hydrolysis of PLLA
O
Trench-like
topographic nanopattern
N [ C C ] m
Semicrystalline copolymer: PS-PLLA
O
H
CH
3
PS PLLA
O H
Amorphous and non-degradable Crystalline and degradable

Strongly Segregated PS-PLLA
Quench from melt
S14-L15
Lamellar morphology
250nm
Strongly Segregated PS-PLLA
RuO 4 staining (dark: PS and bright: PLLA)

Directional eutectic solidification
Strongly Segregated PS-PLLA
500 nm
Homogeneous mixture of substrate and polymer
Quenching
Directional eutectic solidification
for strongly segregated PS-PLLA
Glass slide
PS
PLLA Eutectic liquid
Crystalline substrate
Glass slide

Crystallization-Induced Orientation
Strongly Segregated PS-PLLA
200 nm
Homogeneous mixture of substrate and polymer
Crystalline PLLA
Directional eutectic solidification
for strongly segregated PS-PLLA
Non-lattice matching substrate (HMB)
PS
Glass slide
PS
PLLA Eutectic liquid
Crystalline substrate
Glass slide
Isothermal
crystallization
Crystalline substrate

Lattice Matching Effect
Strongly Segregated PS-PLLA
100 nm
500 m
Homogeneous mixture of substrate and polymer
Crystalline PLLA
Directional eutectic solidification
for strongly segregated PS-PLLA
PS
Glass slide
PS
PLLA Eutectic liquid
Crystalline substrate
Glass slide
Isothermal
crystallization
Crystalline substrate
Lattice matching substrate (BA)
Lattice matching improve nanostructure orientation !!

Lattice Matching
PLLA -PCL
0.514 nm
1.07 nm
Crystalline PLLA lamellae
b
a
PLLA
a
BA
2b
Amorphous PLLA and PCL domain
axis mismatch
b PLLA - a BA
a BA
a PLLA - 2b BA
2b BA
= 7%
= 4%
Ho, R.M. et al., Macromolecules 2003, 36, 9085.
2D Lattice Matching

PS128LLA106 diblock copolymer: Lamellar morphology
Epitaxy-induced Morphology
Phase-separated Morphology
500nm
Area > 150μm 2 !
PLLA(200)
PLLA(110)
500nm

Mechanisms
1.Homogeneous mixture
of solvent and polymer
PS PLLA
Polymer-crystallizable solvent solution
Crystalline substrate
Glass-slide
2.Directional crystallization
of crystallizable solvent
T m, solvent
1
2
L+
5
6
Liquid
+
L+
0 0.5 1
Weight fraction of block copolymer
3.Directional eutectic solidification
for strongly segregated PS-PLLA
T m, PLLA block
T e
T C, PLLA block
T ODT
: Crystalline substrate
: PS-PLLA
4.Isothermal crystallization
Ho, R.-M. et al. Macromolecules 2006, 39, 7071.

Nanopatterning
Nanopattern: pattern with nanoscale features (1~100 nm)
Height profile
Topographic nanopattern
Composition profile
Substrate
Chemical nanopattern

Methods for Nanopatterning
Photolithography?
Excimer Laser Micro-processing?
Soft Lithography?
Scanning Probe Lithography
Electronlithography
Self-assembly of Living Cells, Surfactant,
Dendrimer and Polymer
Bottom-up methods
@Top-down methods
External forces!

Electronlithography
Write with electron beam
Martin, J.I.; Velez, M.; Morales, R. J. Magn. Mater. 2002, 249, 156.

Soft Lithography
Whitesides, G. M. et. al.
J. Mater. Chem. 1997, 7, 1069
Stupp, S. I. et. al.
Nano Lett. 2007, 7, 1165

Nanoimprint Lithography
PMMA film
PMMA film
Au dots
Au lines
Chou, S. Y. et. al. Science 1996, 272, 85

Scanning Probe Lithography
Atomic force microscope tip as a “pen”
A solid-state substrate as “paper”
Molecules with a chemical affinity for
the solid-state substrate as “ink”
Transport of the molecules from the
AFM tip to the solid substrate
Mirkin, C. A. et. al. Science, 1999, 283, 661

Why Degradable Block Copolymers ?
Polyesters: degradable
characteristics for
mesoporous materials
Substrate
Bio-degradation
Chemical degradation
Zalusky, A. S.; Olayo-Valles, R.; Taylor, C.; Hillmyer, M. A.
J. Am. Chem. Soc. 2001, 123, 1519.
Degradable blocks
Non-degradable blocks
Height profile
Substrate
Topographic nanopattern
Nanopatterned template

Advantages and Disadvantages
Electronlithography
PMMA
van Blaaderen, A. et al. Nature 1997, 385, 323.
Require precise manufacturing
(expensive!)
Topographic pattern only
Limitation in pattern area
Creative features
Block copolymer
PS-PLLA
Ho, R.-M. et al. US24265548A1
Large-scale orientation
Easy to prepare (cheap!)
Quick!
Available for topographic and
chemical nanopatterns
Flexibility

Degradation of Block Copolymer
Dry Pyrolysis
PS-PB PS-PMMA PS-PDMS
O3 ; RIE
UV O3 ; RIE
Russell T. P. et al. Adv. Mater.
2000, 12, 787.
Park M, Harrison C, Chaikin P. M., Register R. A.,
Adamson D. H. Science 1997, 276, 1401.
Ross, C.A. et al. Nano. Lett.
2007, 7, 2046.

Nanopatterning from Degradable BCPs
(a)
staining with OsO4 (b) (c)
Spin-coated film
PS-PB m n
O 3
Spin-coated film
with annealing
unstained
Spin-coated film with
annealing
exposure to ozone
@
Register, R. A. et. al. Science, 1997, 276, 1401
Register, R. A. et. al. Appl. Phys. Lett. 2000, 12, 787

Nanopatterning from Degradable BCPs
PS-PMMA
UV
O O
Height image Phase image
m
n
Top-view FESEM
Cross-section-view FESEM
Russell, T. P. et. al. Adv. Mater. 2000, 12, 787
@

Nanopatterning from Degradable BCPs
Methanol 40 V
NaOH+H2O (0.5M) 60 V
PS-PLA bulk Nanoporous bulk
Degradation solution
Hillmyer, M. A. et. al. J. Am. Chem. Soc. 2001, 123, 1519
@

PS-PLLA, Degradable Diblock Copolymers
O
C
PS
O [ CH2 C H ] n
O
H C
3
H C
3
Non-degradable block
CH 3
CH 3
O
PLLA
chiral center
N [ C C ] m
O
*
H
CH
3
O H
Degradable block

Synthetic routes of PS-PLLA block copolymers
O
Ph O
Ph
O N
m
PS-TEMPO-OH
Living free radical polymerization
Living ring-opening polymerization
OH
Toluene
O O
Li TEMPO-PS
O
Li
Li
Li
Li
O
Li TEMPO-PS
O O
Lithium Alkoxide Macroinitiator
OEt 2
O C
Li
O
Li
Li
Li
Li
C
Li
O O
OO
PS H OO
O
3
C
O N O
O
H
O N O
O
H
Ph O
O
P h O
O
C O [ C H C ]
2
H
n
O
Ph
O
P h m
O
*
m n n
Non-biodegradable H Biodegradable
PS-PLLA3
C CH 3
P S - P L L A
CH 3
O
N O [ C C H O ]
m
H
CH 3
+
Lin, C.-C. et al. J. Am. Chem. Soc. 2001, 123, 7973-7977.
n L-LA/ CH 2Cl 2, 0 o C
PLLA
Poly(styrene)-block-Poly(L-lactide) (PS-PLLA)
O -
O -
t-Bu
=
t-Bu
t-Bu
O- O- t-Bu

Log(I)
Various nanostructures of PS-PLLA block copolymers
PS198-PLLA28 (f PLLA v =0.14)
*
q
*
2q
*
3q
*
4q
*
5q
*
6q
*
7q
BCC
*
9q
0.3 0.4 0.5 0.6 0.7 0.8
q(nm -1 )
Similar to PS-PLA!
Log(I)
PS280-PLLA97 (f PLLA v =0.29)
*
q
*
3q
*
4q
*
7q *
9q
HC
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
q(nm -1 )
Log(I)
PS125-PLLA167 (f PLLA v =0.57)
*
q
*
2q
*
3q
*
4q
Lamellae
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8
q(nm -1 )
Ho, R.-M. et al. J. Am. Chem. Soc. 2004, 126, 2704.
100nm
Hillmyer, M. A. et al. J. Am. Chem. Soc. 2002, 124, 12761.

Nanotemplate (i.e., Nanoreactor)
A convenient way to generate organic or inorganic nanostructure!
Substrate
Substrate
(1) Spin-coating
Substrate
(2) Self-assembly
Self-ordering
Substrate
Substrate
Substrate
(3) Hydrolysis
(4) Sol-gel reaction; Porefilling;
Electroplating;
CVD etc.
(5) Remove template
regularly sized and spaced features

Sol-gel Process for NanoTemplates
One example: Nanoreactor for nanoarrays
High-efficiency photocatalysis!
TiO 2 nanoarrays
FESEM Images
Particle array Diameter:20~30nm(sol particle size

Pore-filling for Nanotemplates
Capillary force driven from the
tunable wetting property of
solution for the templates
H 2S vapor
tubular-like
cylinder-like
Ho, R.-M. et al. Macromolecules, 2007, 40, 2621.

air-block releasing
directed capillary force (method 1)
directed capillary force (method 2)

TEM : Air-block releasing
Nanoporous template
Vacuum
Injection
Cd(Ac) 2/methanol
Pump
Vacuum
Reduction by H 2S (g)
inefficient filling
CdS nanocrystals

TEM : directed capillary force (method 1)
Nanoporous template
from hydrolysis by
PS-PLLA thin film
(b)
H 2O solution
Water
lack of wetting capability for
driving of capillary force
grid
Small area !!
grid
Cd(Ac) 2/ X solution
Methanol solution
Reduction by H 2S (g)
partial filling of
going-through solution

TEM : directed capillary force (method 2)
Nanoporous template
Large area !!
Cd(Ac) 2/methanol/water
Cd(Ac) 2/methanol/water
Reduction by H 2S (g)

PL and UV spectra
Exciting length is at 450 nm
a greater density of
CdS nanocrystals
residing in the
template!
No QDE: CdS
nanoparticles > 6
nm).

Confocal Microscopy Observation
CdS solid state
exciting at 454nm and detected from 480nm~600nm
200 μm 200 μm 200 μm
air-block releasing
directed capillary force
The emission intensity of the CdS nanoarray can be
modulated by pore-filling process.

Electroplating of Metallic Materials
Nanoarrays of Catalytic Materials
Ni nanoarrays embedded
in the template of PS
matrix
Eletroplating for the growth of Ni
The exploitation of carbon
nanotubes (CNTs) for display and
lighting purposes require
controlled size, special spacing,
and layout of patterns.
Ni nanoarrays
thermal CVD at
500 o C for CNT
growth
CNT nanoarrarys
Ho, R.-M. et al. Adv. Mater.,
2007, 19, 3584-3588.

Double-length-Scale Patterns
(a)
Conductive Micropatterning
Conductive
Ho, R.-M. et al. Adv. Mater.,
2007, 19, 3584-3588.
P02940028US; P02940028TW
(composite micro- and nano-patterned)
Spin-Coating
PS-PLLA sol.
Lithography
Growing
CNT
Nanopatterning
(b)
Electroplating Template removal
(c)
Electroplating Ni
Block Copolymer
Templating
Electroplating

Screening Effect
High site density (>109 /cm2 )
leading to small electrical
enhancement at the tips. A site
density of about 107 /cm2 (according to electrostatic
calculation) has been
calculated to be the right
number for optimal electron
emission properties in the
sense of both emission site
and current density.
Appl. Phys. Lett., 76, 2071 (2000); Chem. Mater.,
17, 237 (2005); J. Mater. Res., 16, 3246 (2001);
Thin Solid Film, 405, 243 (2002).
Patterns with both in micro-scale and nano-scale for the CNT
arrays have been expected to reach high-field-emission
capability and uniformity.

FESEM images of CNTs grown from PS/Ni composite films
Patterned
cross-section
low magnification high magnification
Non-patterned
FESEM image of CNTs grown from Ni layer

Two-electrode field emission device
Double-length-scale
High current density with
low threshold voltage and
high field emission
efficiency for patterned
CNT arrays!
Single-length-scale
Ho, R.-M. et al. Adv. Mater.,
2007, 19, 3584-3588.

Lighting
DTC
Phosphor (CRT)
Ni on DC-206
Patterning ITO
substrate
two-electrode field emission device
Spacer 150μm
Spacer
FP-R-054-taping
1000v
二極結構

Drug-Eluting Stent for Atherosclerosis
■ Sirolimus: immunosupressive agent with anti-
inflammation and antiproliferation characteristics
■ Metallic stent: prevent vascular recoil
■ Local delivery for the sustained release of drug
Stent implantation during percutaneous
transluminal coronary angioplasty (PTCA)
Mixture of drug and
polymer coated
on the stent for
drug-eluting control
SIBS

Pore-filling for Sirolimus
Capillary force driven from the
tunable wetting property of
aqueous solution for the templates
Ho, R.-M. et al. Macromolecules
2007, 40, 2621.
nanoscale releasing
Ho, R.-M. et al. ACS Nano, 2009, 3, 2260.
Water → enhance the surface
tension for the deposition of
the PS template
Ethanol → wet the PS template
for the driven capillary force

Pore-filling of Sirolimus
Before pore filling After pore filling
TEM images of templated sirolimus nanoarrays

Accumulative Accumulative release release (%) (%)
100
80
60
40
20
Drug-releasing profile PS AAO Sirolimus
24 hr
42 hr
0
0 50 100 150 200 250
Macrostructure
with burst relesae!!
85 hr
extended drugeluting
duration
Time (hr)
Ho, R.-M. et al. ACS Nano, 2009, 3, 2260.

Pore-filling of hydrophilic Conjugated Polymers
Conjugated Polymer
PEO-PPV
Hydrolysis
Solvent
Annealing
14
O
n
HF
code
Mn
(g/mol)
PVE3 10309 1.12
PVE7 14866 1.10
PEO-PPV
Ho, R.-M. et al. Adv. Funct. Mater. 2011, 21, 2729.
PDI Solvent
Acetic
acid
Acetic
acid

Nanoscale Spatial Effect
PY/CM thin film
templated PY/CM
nanoarrays
PVE3
PVE7
with nanoporous template without nanoporous template

PL result : in-situ solvent annealing
PVE3
solvent annealing
PVE7

Chain Alignment Mechanism
Solventannealing
process
Ho, R.-M. et al. Adv. Funct. Mater. 2011, 21, 2729.