It is well known that the behaviour of polymers when they are restricted in space or when they are close to surfaces can be very different from that in the bulk. In this work, we investigate the morphology, crystallization and dynamics of a hydrophilic, semi-crystalline polymer, poly(ethylene oxide), PEO, when mixed with silica, SiO2, nanoparticles in a broad range of compositions. The good dispersion of the nanoparticles was verified by Transmission Electron Microscopy (TEM), whereas the morphology and crystallization behaviour of the hybrids were investigated with, X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). All techniques show a gradual decrease of polymer crystallinity with increasing the amount of nanoparticles; nevertheless, polymer crystallization is observed for all silica loadings. Moreover, DSC measurements showed the existence of two melting and crystallization transitions in hybrids with polymer content lower than 50wt%, indicating that the polymer crystallizes differently than the bulk near the silica surface

1. 5 10 15 20 25 30
Intensity(a.u.)
80%
20%
30%
35%
40%
32%
38%
50%
60%
70%
90%
100%
Peo
Content
 (
o
)
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
10
6
0.02
0.04
0.06
''
Frequency (Hz)
100% PEOT=-70
o
C
T=-80
o
C
T=-90
o
C
T=-100
o
C
T=-110
o
C
T=-120
o
C
T=-130
o
C
10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
10
6
0.05
0.1
0.15
0.2
0.25
0.3
''
35% PEO - 65% SiO2
T=-38
o
C
T=-41
o
C
T=-44
o
C
T=-47
o
C
T=-50
o
C
T=-53
o
C
Frequency (Hz)
10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
10
6
0.02
0.04
0.06
0.08
''
Frequency (Hz)
T=-70
o
C
T=-80
o
C
T=-90
o
C
T=-100
o
C
T=-110
o
C
T=-120
o
C
T=-130
o
C
35% PEO - 65% SiO2
10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
10
5
10
6
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
0.22
0.24
''
T=-38
o
C
T=-41
o
C
T=-44
o
C
T=-47
o
C
T=-50
o
C
T=-53
o
C
Frequency (Hz)
100% PEO
-100 -50 0 50 100
HeatFlow/polymermass(calg
-1o
C
-1
)
32%
35%
38%
100%
50%
20%
40%
70%
80%
30%
60%
90%
Temperature (
o
C)
95%
PEO content
M O R P H O L O G Y
D Y N A M I C S
C O N C L U S I O N S
A C K N O W L E D G E M E N T S
This work was performed in the framework of PROENYL research project, Action KRIPIS, project MIS-448305 (2013SE01380034), funded by the General Secretariat for Research and Technology, Ministry of Education, Greece and the
European Regional Development Fund (Sectoral Operational Programme: Competitiveness and Entrepreneurship, NSRF 2007-2013)/ European Commission
COST Action MP0902-COINAPO (STSM-MP0902-14971) and COST Action MP1202-HINT.
3.6 4.0 4.4 4.8 5.2 5.6 6.0 6.4 6.8 7.2
-2
-1
0
1
2
3
4
5
6
7
-log(max
/s)
1000/T (K
-1
)
100% PEO
80% PEO
35% PEO
30% PEO
20% PEO
35%PEO-65% SiO2 80%PEO-20% SiO2 99%PEO-1% SiO2
Good dispersion of the
nanoparticles seen both in
SEM and TEM with nearly no
aggregation
 Crystallinity gradually
decreases
 Increase of the
amorphous halo due to
both increase of the
amorphous polymer and
the presence of the
nanoparticles
 Sharp peaks due to the
crystalline polymer
 Gradual decrease of
intensity of the peaks due
to the crystalline PEO
 The crystalline character of
PEO is observed in the
whole composition range
 The fast process is observed below the Tg and is similar to that of the pure PEO as is
the segmental process.
 The intermediate process attributed to severely confined polymer chains is not
present in any of the nanocomposites.
 The intermediate process is present in pure PEO and is attributed to chains being
confined between crystal walls.
C R Y S T A L L I Z A T I O N
Addition of nanosized inorganic materials in a polymeric matrix results to nanohybrids with
optimized properties with respect to the initial components. On the other hand, the behaviour of
polymers when they are restricted in space or when they are close to surfaces can be very different
from that in the bulk. In this work, we investigate the morphology, crystallization and dynamics of
a hydrophilic, semi-crystalline polymer, poly(ethylene oxide), PEO, when mixed with silica, SiO2,
nanoparticles in a broad range of compositions. The good dispersion of the nanoparticles was
verified by Transmission Electron Microscopy (TEM). The effect of the proximity to the silica
surface on polymer dynamics was investigated with Broadband Dielectric Spectroscopy, (BDS)
whereas the morphology and crystallization behaviour of the hybrids were investigated with, X-
ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), and Differential
Scanning Calorimetry (DSC).
M A T E R I A L S
Poly (ethylene oxide)
Mw=100.000
Tm=67 oC, Tg=-67 oC
Crystallinity= 75-80%
SiO2 Nanoparticles
R=6-8 nm
Suspended in water
 Pure PEO completely melts above the Tm
 Gradual decrease of crystallinity was observed utilizing IR, XRD and DSC
 A second melting transition were observed for compositions lower than 50% polymer attributed to
polymer chains crystallizing in the proximity of silica surfaces.
 Dielectric relaxation spectroscopy reveals the existence of two relaxation processes one below and one
above Tg.
 The fast process is similar for all hybrids and for the pure polymer and is attributed to the β relaxation.
 The segmental process becomes faster with the addition of more nanoparticles
 Nanocomposites with double melting
temperatures exhibit partially melted states
between the two melting temperatures
SEMTEM
1300 1400 1500 3000
35
38
32
Absorbance(a.u.)
Wavelength (cm
-1
)
20
30
40
50
60
70
80
90
100
PEO%
DSCATR-IR XRD
ATR-IR : EFFECT OF TEMPERATURE
The second melting peak indicates that
PEO under confinement crystallizes
differently than in the bulk
0 20 40 60 80 100
0
10
20
30
40
50
60
70
80
90
100
%Crystallinity
% PEO content
Crystallinity measured by XRD
Crystallinity measured by DSC (Both peaks)
Crystallinity measured by DSC (Main peak)
 Crystallinity gradually decreases
 A second melting peak appears
for hybrids with less than 50%
PEO
 The new melting transition
shows a composition dependent
Tm and prevails for hybrids with
low polymer content.
1200 1250 1300 1350 1400
Wavenumbers (cm
-1
)
T=120
o
C
100% PEOTm
=68.5
o
C
T=40
o
C
T=110
o
C
T=100
o
C
T=90
o
C
T=50
o
C
T=60
o
C
T=80
o
C
T=70
o
C
T=22
o
C
1300 1320 1340 1360 1380 1400
Wavenumbers (cm
-1
)
T=120
o
C
T=100
o
C
T=90
o
C
T=30
o
C
T=70
o
C
T=60
o
C
T=58
o
C
T=54
o
C
T=50
o
C
T=34
o
C
T=38
o
C
T=44
o
C
T=48
o
C
T=40
o
C
maximum=49
o
C
30% PEO
Tm2
=38.7
o
C
Tm1
=55.4
o
C
T=27
o
C