Functional Polymers From
Renewable Resources
S. Shang, A. Ro, S. J. Huang and R. A. Weiss
Polymer Program
University of Connecticut
Storrs, CT
New England Green Chemistry Consortium Annual Meeting
University of Maine
Orno, ME
May 31, 2006
Polymers based on renewable resources
crops, grasses, agricultural byproducts
Raw materials are sustainable;
Polymers can be designed to be biodegradable
O
O
Monomers From Renewable Resources
Lactic Acid
O
CH3
HO
Itaconic Anhydride
OH
Stearyl
Methacrylate
O
O
O
Fermentation of agricultural
by-products (carbohydrates),
e.g., corn starch
Pyrolysis of citric acid, or
Fermentation of carbohydrates
to form itaconic acid, followed
by dehydration
Derived from fatty
acid from animal or
vegetable fats or
oils
Poly(lactic acid), PLA
CH3
CH3
Azeotropic Distillation
- H2O
OH
*
*
O
HO
O
O
High Molecular Weight PLA
n
Ring Opening Polymerization
(SnOct2 with coinitiator)
Condensation
-H2O
O
Depolymerization
SnOct2
CH3
H
H3C
O
OH
O
O
O
Prepolymer
Mn ~ 5000
CH3
n
O
Lactide
Drumwright, R. E.; Gruber, P. R.; Henton, D. E. Adv. Mater. 2000. 12. 1841.
Applications: Fibers, films, moldable thermoplastics (Tm ~ 175C), sutures
Deficiencies: Low Tg (~ 60C), Narrow melt processing window, Brittle plastic,
hydrophobic; incompatible with other polymers (blends)
Ionomers
Predominantly hydrophobic polymers that contain modest
amounts of bonded acid or salt groups (~ 15 mol%)
Interchain association of salt groups significantly alters thermal
properties, mechanical properties and rheology.
PS
1.82 NaSPS
3.44 NaSPS
5.81 NaSPS
Applications: coatings, fibers, thermoplastics, adhesion promoters,
compatibilizers, viscosifiers, permselective membranes, hydrogels…
Research Goals
Synthesize and Characterize Ionomers Derived from Lactic
Acid, Itaconic Anhydride and Stearyl Methacrylate
CH3
H2
C
O
Random Ionomer
-+
n
C
C
H2
O
O
O
O
ITA
O
CH
m
C
O
H2C
ITA
C
H2
O
CH2
O
-+
C
C
n
m
O
O
CH3
H2
C
CH3
H2C
O
x
H
a
Telechelic
Ionomer
CH3
O
O
O
O
O
O
Telechelic PLA A
O
H
+
-+
O
n
-+
itaconic ahydride
ethyl acetate, O
120oC, SnOct2
PLA
b
SM
O
O
O
O
O
telechelic PLA B
PLA
OH
n
O
ITA
O
-+
Radical copolymerizaton of ITA and SM
AIBN, 80oC
+
O
O
O
O
O
5
O
No peak
Absorption
O
O
Ethyl
Acetae
1782
co(ITA/SM)
CH2 C
n
CH2
O
1.5
Copolymer
1731
O
2.0
O
1862
m
O
1730
O
(CH2)17CH3
O
SM
(CH2)17CH3
4
O
O
(CH2)17CH3
AIBN, 80o C
O+
O
(CH2)17CH3
3
Mixture
1.0
Copolymer
ITA
0.0
1800
2500
Ethyl Acetae
(CH2)17CH3
Mixture
SM
3000
O
O
0.5
1
AIBN, 80o C
O+
1720
O
O
2
0
m
O
Ethyl Acetate
O
ITA
6
n
2000
1500
1780
1760
1740
1720
1700
1000
1680
1660
1601
Wavelength (cm-1)
IR evidence for copolymerizaiton:

1862, 1782 cm-1: ITA (anhydride) 5 member ring

shift of C=O in SM from 1720 to 1731 cm-1 indicating reaction of C=C

disappearance of peak at 1601 cm-1: reaction of C=C
CH2
O
Copolymerization of ITA and SM
1.0
0.8
FITA
rITA = r1 = 0.53
r1 f12  f1 f 2
F1 
r1 f12  2 f1 f 2  r2 f 22
rSM = r2 = 0.12
0.6
Random
Copolymers
0.4
0.2
0.0
0.0
J. Wallach, PhD Dissertation,
Univ. Conn., 2000
0.2
0.4
0.6
0.8
1.0
fITA
Mn (25k – 60kDa) decreased with increasing fITA
Thermal behavior of ITA-co-SM copolymers
DSC: 1st scan after ppt from soln.
10
Increasing SM composition
g
Heat Flow (W/g)
f
0
e
d
c
b
-10
a
-20
-40
-20
0
20
40
60
80
100
fITA
Mn (kDa)
Tm (C)
DH
(J/g SM)
0
57.1
30.2
62.8
0.29
45.1
31.2
83.0
0.40
33.0
32.1
77.0
0.53
34.8
44.7
87.9
0.54
29.1
48.2
50.9
0.45
24.1
45.6
21.3
120
o
Temperature ( C)
Crystallinity is due to the SM side chain packing
Melting temperature increased with increasing ITA content!
Effect of ITA on crystallinity was complicated.
No glass transition was observed (Tg(ITA) ~ 130C).
Crystalline structure of ITA-co-SM
SAXS
(100 % ITA)
Intensity
(45)
(53.8)
(52.8)
(29.0)
(0)
0.5
1.0
1.5
2.0
2.5
3.0
d (nm)
0
2.95
29.0
2.96
45
52.8
3.98
3.18
53.8
3.55
100
--
Length of alkyl side chain = 2.5 nm
q (nm-1)
WAXD
Composition
(mol% ITA)
(58% ITA)
Intensity
(45)
(53)
0.417 nm
characteristic of n-alkyl
hexagonal packing,
(45)
(29)
Poly(SM)
10
12
14
16
q (nm-1)
18
20
Side-Chain, Stearyl Methacrylate Crystals
L
L
L
Intercalated Crystal
Bilayer Crystal
3.9 nm
27
Zn-Stearate Bilayer Crystal
ITA-co-SM Ionomers
(Mn=33 kDa; 40 mol% ITA)
1630
1570
2+
Ca Salt (50%)
1570
Na+ Salt (100%)
ITA-co-SM (40% ITA)
2000
1900
1800
1700
1600
1500
Wavenumber (cm-1)
IR evidence of neutralization
Peak ~ 1550-1650 cm-1 due to COO-
1400
Ionomer Structure and Properties
TMA (F = 60 mN)
SAXS
1.0
Ca-salt (50%)
ITA-co-SM (40% ITA)
Probe Height
Intensity
Na-salt (100%)
Poly(SM)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
Na-Salt (100%)
0.8
ITA-co-SM
(40% ITA)
0.6
0.4
Ca-Salt (50%)
0.2
0.0
3.5
q (nm-1)
0
20
40
60
o
Temperature ( C)
Ionic aggregation was observed
Long spacing of SM crystals increased upon neutralization
Neutralization increased the elasticity of the polymer.
80
Chemical Recycling of PLA by Transesterification
Transesterification
 Uncatalyzed - slow process, reaction temperature 250-300C.
 Catalyzed - lower time and temperature (J. Wallach, PhD Dissertation,
Univ. Conn., 2000).
– SnOct2. FDA approved.
Mechanism
R
O
CH3
O
O
H
CH3
O
O
O
OH
O
OH
O
O
O
Sn
Oct2 H
O
O
R
SnOct2
CH3
O
OH
+ R
O
O
OH
O
O
SnOct2
Synthesis of ω-carboxylate
functionalized PLA
A. Synthesis of methacrylate-terminated PLA
O
O
OH +
O
O
CH3
SnOct2
O
HO
O
H
n
O
n
CH3
2-hydroxyethyl methacrylate
H
O
O
poly(lactic acid)
telechelic PLA A
B. Functionalization with itaconic anhydride
O
CH3
O
O
O
Telechelic PLA A
O
O
H
+
O
O
n
itaconic ahydride
ethyl acetate, O
120oC, SnOct2
O
O
O
O
O
telechelic PLA B
OH
n
O
O
O
O
O
O
O
Broad OH stretch
OH
n
C=O stretch
O
C-O-H in-plane
bend and C-O
stretch
Carboxylic
C=O stretch
C=C
stretch
O
O
O
O
O
O
O
n
M
O
Asymmetric
carboxylate
anion stretch
1H-NMR
Spectrum of
Functionalized PLA Oligomer
d
End group Analysis Mn = 1930, with
25 LLA units
c
c d h
h
Glass Transition Temperatures of
PLA-ITA Telechelic Ionomers
Cations = Li+, Na+, K+, Ca2+, Zn2+, Y3+
55
50
c = 0.6 mol%
(M ~ 13,000 g/mole)
o
Tg ( C)
45
40
c = 2.1 mol%
M ~ 3,000 g/mole
35
30
25
0.0
Ca
K Na Li
0.2
0.4
0.6
0.8
1.0
1.2
Zn
1.4
Y
1.6
1.8
q/a
For higher molecular weight (M ~ 15,000 – 900,000),
Tg was relatively insensitive to functionalization
Acknowledgments
Funding by:
New England Green Chemistry Consortium
NSF/EPA
Petroleum-Based Polymers
*
Hydrophobic and resistant to biodegradation
Escalating prices of petroleum (only ~ 2% of
petroleum is used for polymers)
* Municipal Solid Waste Generation, Recycling, and Disposal in the United States: Facts
and Figures for 2003, U.S. Environmental Protection Agency, 2003.
Tullo, Chem. Eng. News. 2005, 83, 19.
Environmental Concerns
Plastics production has nearly doubled every 10 years for four decades.
Environmental Issue
Plastic are the largest volume
component in U.S. landfills (~ 25%)
Sustainability Issue
Existing petroleum resources are limited.
Biodegradable Polymers
Aliphatic Polyesters from Hydroxyacids
Poly(3-hydroxybutyric acid)
O
CH3
O
Poly(lactic acid)
NatureWorks LLC
CH3
O
O n
n
Itaconic Anhydride
• Ramos – PEG functionalization
O


O


A
RO
OH
ROH

O
O
SnOct2
O
RO
B
OH
O 
O
• Biocompatible – citric acid distillation,
fermentation of carbohydrates (Aspergillus
terreus)
Ramos, M. Multi-component Hydrophilic-Hydrophobic Systems From Itaconic Anhydride. Ph.D. Thesis, University of Connecticut, Storrs, CT, 2002.