Polyester matrices :
role of clays and organo-modification




Biodegradable Aliphatic Polyesters
Biodegradable polymers with controllable life-time
Via enzymatic/hydrolytic chain cleavage and ultimate
bioassimilation
Biocompatible and bioresorbable materials
O (C H
2
)
5
C
O
n
PCL
Industrial production of PCL by Solvay, Dow (Union Carbide), Daicel,…
Miscible with numerous commercial thermoplastics…
e.g., PVC, SAN, ABS, CPE, nitrocellulose, polycarbonate, (PE),…
Poly(ε-caprolactone) :

Nanocomposites :
organic-inorganic materials
 
First
: to improve properties of PCL :
stiffness, gas barrier,

ε-caprolactone + clay + catalyst
Clay = Montmorillonite
Na
x
(Al
4-x
Mg
x
)Si
8
O
20
(OH)
4
[CEC = 80-100 mequ./100 g]
from Southern Clay Products or Süd Chemie

commercial PCL
Mn = 50,000 g.mol
-1
Montmorillonite (modified)
3 wt%
melt blending on a two-roll mill at 130°C for 10 minutes
+
Poly(ε-caprolactone) nanocomposites by melt intercalation

basal spacing (d, Å) in code Ammonium cation
(organic fraction wt %)
a


+
(C
18
H
37
)
2
(28.9) ca. 29.0
(broad)
36.0
Mont-(OH)
2
(CH
3
)(C
18
H
35
)N
+
(CH
2
CH
2
OH)
2
(20.1) 18.4 31.0

microcomposite
Intercalated

N
+
(CH
3
)
2

(C
18
H
35
)(CH
3
)N
+
(CH
2
CH
2
OH)
2
Exfoliation of the silicate sheets in PCL never complete, it remains some stacks of
silicate layers whatever the alkylammonium cations considered
semi-intercalated/semi-exfoliated structure

~50nm
(Nanofil 848) (Nanofil 15) (Cloisite 30B)

Effect of clay content on elastic modulus
150

(CH
2
)
5
O
n

n
Poly(ε-caprolactone) nanocomposites by
in situ
polymerization
Pantoustier et al, Polym. Eng. Sci., 42
(2002) In-situ
polymerization
[monomer]/[Sn(Oct)
2
] = 300
3 wt-% clay
analysis by X-ray diffraction
Montmorillonite
N
+
CH
3
CH
3
C

(2002)

100 nm
100 nm
Complete exfoliation
,!'
(catalysis by '
-
".&
-
T.E.M.
0 5 10 15 20 25 30
2 theta
counts
1 wt%
3 wt%
5 wt%
10 wt%
MMT-(CH
2
CH
2
OH)
2
3.25 Å
3.74 Å
4.14 Å
XRD
N
+

OHOH
R
N
+
OHOH
R
N
+
OHOH
R
N
+
OHOH
R
N
+
OHOH
R
R=C
18
H
35
O
O
N
+
OH
OH
R
N

2
)
2
+ C
2
H
6
N
+
C
18
H
37
CH
3
OH
OH
Mont-(OH)
2

I
-
By !(in H
2
O at 85°C) of hydroxy-functionalized
and non functionalized ammonium cations :
Na
+
Na
+

37
N
CH
3
CH
3
CH
2
CH
2
OH
C
18
H
37
N
CH
3
CH
3
CH
3
1.21nm
with 0, 25, 50, 75 and 100%
intercalated ω-OH ammonium cations
(ca. 21~wt-% organic
modifier)
~1.9nm
0
500

Intercalation
Exfoliation
Lepoittevin et al., J. Mater. Chem., 12
(2002)

3 wt-% Mont-OH
(100%)
100 nm
~300nm
PCL-« grafted » clay nanohybrids : grafting density control

OHHO
O O O
O OO
Where represents the long alkyl chain ammonium
cations, some of them bearing an hydroxyl function (–OH)
Polymerization
Induced
phase-separation
Polymer patch (~ 2-3 nm high)
"grafted" polymer layer
(5-8 nm thick)
Individual clay
platelet (~ 1nm thick)
low grafting
density
high grafting
density
< 50% (OH)
≥ 50% (OH)

Proposed mechanism:
Viville et al., J. Amer. Chem. Soc.,
2004

Nanohybrids by sequential copolymerization of ε-
caprolactone and L,L-lactide from activated clay surface
N
+
C
16
H
33
O C CH
2
O
O Al
n

5
Et
Et
N
+
C
16
H
33
O
O
O

+
C
16
H
33
OH
N
+
C
16
H
33
N
+
C
16
H
33
O Al
Et
Et
N
+
C
16
H
33
AlEt
3
-

200
400
600
800
1000
1200
1400
1600
0 2 4 6 8 10 12 14
2 theta angle (°)
counts (a.u.)
MMT + PCL-b-PLA
MMT + PCL
Cloisite30B
a)
b)
c)
a)
b)
c)
Pollet et al., Macromol. Chem. Phys.,
2004

Catalyzed
ROP
O
O
O
O
O

Lepoittevin et al., Polymer, 44
(2003)
45
5
56!'(

0
20
40
60
80
100
250 300 350 400 450 500 550
temperature °C
weight %
PCL
1 w t%
3 w t%
5 w t%
10 w t%
Conditions : 20°C/min. under air flow
Thermogravimetric analysis of PCL-grafted Mont-(OH)
2

exfoliated in PCL via «&masterbatch&» process : ###

PCL 50K
Lepoittevin et al., Polymer, 44
(2003)



5 00 nm5 00 nm5 00 nm
500 nm
Nanocomposites based on 3wt% clay dispersed in stabilized CPE matrix
The large "round" particles are additives within the commercial CPE matrix
Via the PCL-grafted MMT masterbatchWith MMT-OH
2

7#0$*$% 7!"8&
+9*

(melt blending at 175°C; ASTM D638 typeV)
CPE with 36wt% chlorine (Tyrin®3652) from Dupont Dow Elastomers
and stabilized by 4 phr Lankroflex® E2307 (epoxidized soybean oil)
500 nm
CPE+ 14wt% PCL(4K)

CPE
CPE+ PCL-grafted MMT
With elongation at break > 900%

masterbatch process :
application to PLA
nanocomposites
Cloisite
®
30B / PLA
nanocomposites
with 3 wt% of
loading

Cloisite
®
30B / PLA
nanocomposites
with 3 wt% of
loading
Exfoliation of clay
platelets