ADVANCED BIO-FRIENDLY POLYMERS
Eva Papajová
Mechanochemical degradation, degradation by O3, radiolytic
degradation, burning
Thermal degradation
Thermooxidation
Photodegradation
Photooxidation
Hydrolytic degradation
Biodegradation
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Decomposition of polymer chain by reaction with water.
in relation with ester bond
of polyesters
pH initiated  pH < 7 (acid)
 pH > 7 (basic)
Decomposition of polymer chain by reaction with water.
RX + HOH → ROH + HX
Ability of polymers to degrade by hydrolysis is given by difference
in electronegativity of atoms in polymer chain or side groups.
O
R
1
X
R
2
+ H+
O
H2O
R
1
1
X
+
CX R
2
O
R
1
R
2
+
-
OH
H2O
1
R
+
C X
2
+
R
+
R
+
XH
+
H
XH
+
OH
OH
HO
O
R
H2O
O
2
R
H2O
R
1
2
-
OH
OH
5
 polyanhydrides
 polyesters
 polyamides
 polyethers
 polyether urethanes
 polyurea
 polycarbonates
Depends on
 repulsive interactions with ions
 availability of reacting bonds
 physical parameters (swelling, transport of ions along polymer chain)
Water as a carrier of microorganisms
for biodegradation of polymer material.
 degradation process resulting from the action of naturally occuring
microorganisms such as bacteria, fungi and algae
microorganisms can use their enzymes for cleavage of the
polymer chain at the specific location and use them as a source
of energy
 structure of the polymer makes it biodegradable
Enzymes responsible for the biodegradation process
EXOGENEOUS CELLULAR ENZYMES
1st step
ENDOCELLULAR ENZYMES
2nd step
1st STEP EXTRACELLULAR ENZYMES
 enzyme secreted by cell that works outside of that cell
 used for cleavage of long polymer chain in order to permeate through cell
membrane
Depolymerization
(oligomers, dimers, monomers, ...)
Cell
Preliminary degradation (photodegradation, photooxidation, chemical degradation, etc.)
enhances biodegradation process.
Material changes
- important mostly for characterization of the first step of biodegradation
 Mechanical properties (tensile or dynamic analysis)
 Molecular weight of polymer chains (size-exclusion chromatography)
 Degradation in crystalline or amorphous region (differential scanning
calorimetry)
 Structure of polymer material (scanning electron microscopy, contact angle
measurements)
 Changes in polymer structure (spectroscopy techniques – NMR, IR, MS)
Enzymes responsible for the biodegradation process
EXOGENEOUS CELLULAR ENZYMES
1st step
ENDOCELLULAR ENZYMES
2nd step
2nd STEP
ENDOCELLULAR ENZYMES
 enzyme works inside the cell in which it was produced
 carbon and energy sources are metabolized
Mineralization
Cell
Products
in presence of O2
CO2, H2O
in absence of O2
CH4, CO2
Production of gasses
- characteristic for mineralization process
Devices for measuring composition of gasses (O2, CO2, CH4)
 Gas chromatography
 IR spectroscopy (CO2)
 Paramagnetic resonance (O2)
 Measurement of pressure (O2)
 Amount of absorbed gasses measured by titration technique (CO2)
Biodegradation process is dependent on factors ....
Polymer characteristics
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Flexibility
Crystallinity
Morphology
Functional groups
Crosslinking
Molecular weight
Copolymers
Blend
Tacticity
Additives
Exposure conditions
Abiotic
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Temperature
Moisture
pH
UV radiation
Biotic
 Extracellular
enzymes
 Hydrophobicity
 Biosurfactants
accessability of water and microogranisms
functional groups and additives as an active points for initiation of degradation
Crystallinity of polymers
Decreasing rate of degradation
Poly(L-lactide)
Lamella
Increasing crystallinity
Amorphous region
Tsuji, H., Miyauchi, S. (2001) Polymer
Degradation and Stability 71, 415.
poly(ε-caprolactone) (PCL)
O
( O
(CH2)5
poly(3-hydroxybutyrate-co-3-hydroxyvalerate)
(PHBV)
CH3
C )n
( C
poly(butylene succinate) (PBS)
O
C
CH2
O )
m
( C
CH2
poly(lactide) (PLA)
O
O
(CH2)4
CH2
CH2
O
3.5:1
5:1
( O
CH3
O
(CH2)2
3:1
C )n
CH3
( O
CH
O
C )n
1:1
Hydrolytic degradation
PCL < PHBV < PBS < PLA
Biodegradation
PCL > PHBV > PBS > PLA
CH2
O )n
Simulations
(reactor)
Analysis in the nature
 water, soil, compost or material from
dump
 complexity of parameters
 defined conditions
 water, soil, compost, dump
 complexity of parameters
 variability of conditions
Relevance of the information
Laboratory analysis
 enzymes, individual and mixed cultures of
microorganisms
 artificial conditions
 precisely defined conditions
Biodegradable polymers
 starch
 poly(hydroxybutyrate)
 cellulose
 poly(lactide)
 pectin
 polycaprolactone
 gelatine
medicinal
sutures
drug delivery systems
orthopedic fixation devices
replacing a bone cement
industrial
mulching foils
plant pots
silage foils
packaging (bags, boxes)
tooth brush handles
others
... textile, electronics, houseware